RU2183724C2 - Method of recovery of bottom-hole formation zone of gas well - Google Patents

Abstract

FIELD: gas producing industry; applicable in recovery of bottom-hole formation zone and isolation of water inflow in casing string - borehole annulus in major repair of gas wells. SUBSTANCE: method includes preparation of oil-emulsion grouting slurry. Volumes of portions of oil-emulsion grouting slurry and displacing fluid are calculated by empirical formulas. Oil-emulsion grouting slurry is injected and forced through tubing string with simultaneous withdrawal of gas through tubing string. Depression on formation is gradually increased up to beginning of formation water carrying out. In the course of injection and forcing of oil-emulsion grouting slurry, value of actual wellhead gas pressure is compared with its maximum permissible value which is determined by empirical formula. Upon attainment of maximum value of wellhead gas pressure, gas bleeding off is started. Bleeding off rate is calculated by empirical formula. Gas is bled off until moment of ending of injection and forcing of oil-emulsion slurry. Well is killed. Excessive grouting slurry is washed out. Cement sleeve is removed from flow string. Sump is cleaned. Setting of grouting slurry is waited for. Well is completed. EFFECT: higher efficiency and reliability of recovery of bottom-hole formation zone with simultaneous shutoff of water inflow to casing-string - borehole annulus with preserved reservoir properties of formation. 2 cl, 4 dwg

Description

 The invention relates to the gas industry and can be used to restore the bottom-hole zone of the formation and isolate annular water inflow in the interval of slaughter of a closed structure during the overhaul of gas wells.

Analysis of the current level of technology showed the following:
There is a method of fixing loose sands on underground gas storages, including removing sand plugs from a wellbore hole, lowering a tubing string with a packer and installing it above the upper boundary of the perforation interval, developing a well, injecting phenol alcohol into the tubing string a volume equal to the volume of the pore space of the formation with a radius of 1 meter, pushing the latter into the formation with hydrocarbon fluid, pumping warm gas into the formation during the curing of the resin, putting the well into operation (See. Shirkovsky AI Development and exploitation of gas and gas condensate fields. Textbook for high schools. Moscow, Nedra, 1987, pp. 79-81).

The disadvantages of this method are the inefficiency and unreliability of the restoration of the bottom-hole formation zone, the inability to isolate the annulus, the deterioration of the operational characteristics of the system "restored bottom-hole formation-well", the duration of the overhaul of wells. This is due to the following reasons:
the action of the method is based on the fixing of loose sand with hardened resin filling its pore space. The reservoir properties of the rock thus hardened inevitably deteriorate due to a decrease in its effective porosity. The downhole cavity in the destroyed bottom-hole formation zone is not eliminated by the known method. With a large volume of the indicated cavity, the resin accumulates in its lower part, without penetrating into the pore space of loose sand. As a result, the indicated part of the filter zone of the well turns out to be sealed with an impermeable cured resin monolith. Unhardened sand in the vaulted part of the cavity collapses during well development and clumps its remaining filter zone. When the cavity is completely filled with resin with a small volume after curing, the filter part of the well loses its transmittance;
isolation of the lower annular water inflow is based on filling cracks in the cement ring around the production string and the lower part of the borehole with an impenetrable cured resin monolith. When the resin is mixed from phenol-alcohol and produced water in the indicated destruction zones, an uncured mixture is formed, which is washed out from it during intense annular water inflow, and the water inflow channel is not eliminated. Upon elimination of the annular channel of the water inflow, the flow of produced water is redistributed into the communicating pores of the strengthened sand. In addition, with the successful liquidation of the lower annular water inflow, an additional set of works is required to restore the bottom-hole zone of the formation, at the same time the method involves preliminary killing of the well, which increases the duration of the overhaul;
There is a known method of creating an annular artificial filter in an oil well, including killing a well, removing sand plugs, lowering the tubing to the lower boundary of the perforation interval, preparing grouting mortar — Kontaren-2 — sequentially injecting a separating portion of oil and grouting mortar into the tubing, forcing the grouting mortar through the tubing string with the annulus open until the latter reaches the perforation interval, closing the annulus and forcing the grouting mortar through p perforation holes in the bottom-hole zone of the formation, stopping the forcing when the pressure in the annulus increases to the pressure of the casing or after forcing the entire volume of the grouting fluid from the tubing, removing excess grouting mortar from the tubing by backwashing, creating repression on the reservoir, waiting for the curing of the grouting fluid, well development (see M.O. Ashrafyan, O. A. Lebedev, N. M. Sarkisov. Improving the design of the bottom faces of wells. Moscow, Nedra, 1987, p. 102).

The disadvantages of this method are the low efficiency and unreliability of the restoration of the bottom-hole formation zone, the inability to isolate the annular water inflow, the deterioration of the operational characteristics of the "restored bottom-hole formation-well" system, the length of the overhaul of the well, and the insufficient safety when implementing the method. This is due to the following reasons:
the destroyed bottom-hole zone of the formation in the form of a borehole and fracture channels in the formation itself and the cement ring around the production string are not pre-cleaned. As a result, the products of rock and cement stone destruction clog the indicated channels while advancing the crushed cement slurry through them, without ensuring its deep penetration. The cement slurry is transported to the bottom in a well filled with a kill fluid, and is crushed into a near-well fracture zone filled with formation water. Due to the mixing of the cement slurry with the indicated fluids, its spreadability decreases, which leads to an increase in pressure when the thickened cement slurry is crushed into the near-well fracture zone. The combination of these factors determines the incomplete filling of the cavity. In addition, the dilution of the cement slurry with produced water and a kill fluid leads to a deterioration in the mechanical and filtration characteristics of the stone formed from it up to the formation of an uncured mixture. Removing excess cement slurry from the wellbore by reverse circulation with a fixed location of the tubing shoe at the lower boundary of the perforation interval does not provide for the cleaning of perforations. As a result, they remain filled with the formed stone, which sharply increases the filtration resistance of the system "restored bottom-hole formation zone - well";
the cement slurry Kontaren-2 used after curing forms a gas-permeable stone, and this, in turn, necessitates an additional set of works to isolate the annular water inflow. In addition, the method is implemented in a plugged well, which requires additional time costs for a major overhaul;
control over the process of filling the destroyed bottom-hole formation zone with cement slurry is possible only in wells that hold a static level at the wellhead. In gas wells with abnormally low reservoir pressures, the static level drops below the wellhead, which makes it difficult to carry out the indicated control;
as a prototype, a method was taken to strengthen the bottom-hole zone of a gas well formation, including killing a well, flushing a well in the interval of perforation of a production string and sump, preparing a cement slurry - cement-solar-expanded clay mixture - forming a gas-permeable stone after curing, pumping and forcing it along the column Tubing with a squeezing fluid through the perforations of the production string, leaching of excess cement slurry from the tubing string and tubing annulus, waiting for the curing of the cement slurry, drilling a cement-expanded clay glass to the lower boundary of the perforation interval of the production string, well development (see Basarygin Yu.M., Makarenko P.P., Mavromati V.D. Repair of gas wells. Moscow, Nedra, 1998, p. 110-111).

The disadvantages of this method are the low efficiency and unreliability of the restoration of the bottom-hole formation zone, the inability to isolate the annulus, the deterioration of the operational characteristics of the system "restored bottom-hole formation-well", the duration of the overhaul of wells, insufficient safety during the implementation of the method. This is due to the following reasons:
the destroyed bottom-hole zone of the formation in the form of a borehole and fracture channels in the formation itself and the cement ring around the production string are not pre-cleaned. As a result, the products of the destruction of the rock and cement stone clog the indicated channels while advancing through them crushed grouting mortar. Expanded clay component of cement slurry with a size of 0.4-2.5 mm also prevents its deep penetration into the fracture channels. The cement slurry is transported to the bottom in a well filled with a kill fluid, and is crushed into a near-well fracture zone filled with formation water. The cement slurry used - cement-solar-expanded clay mixture - when mixed with these fluids loses its stability. Expanded clay particles are deposited in the lower part of the borehole cavity. When downhole pressure is applied, water is filtered out from the surrounding particles of hydrated cement. As a result, the particles are loosely bound by an unstable cement stone. The specified complex is easily destroyed during the development and operation of the well. The upper part of the borehole cavity is filled with a cement-solar mixture, which easily penetrates into the pore space of the reservoir. With a slight dilution with water, the cement-solar mixture cures. With significant dilution, an uncured mixture forms. In both of these cases, the upper filter zone of the borehole and the part of the reservoir layer adjacent to the cavity appear to be clogged up to the loss of transmission capacity;
the removal of the glass from the production casing by the method of drilling after curing of the cement slurry does not provide cleaning of the perforations. As a result, they remain filled with the formed stone, which sharply increases the filtration resistance of the system "restored bottom-hole formation zone - well". The vibration of the production string arising during the drilling of cement stone destroys the stone in the restored bottomhole formation zone;
used cement slurry - cement-solar-expanded clay mixture - after curing forms a gas-permeable stone, which necessitates an additional set of works to isolate annular water inflow;
control over the process of filling the destroyed bottom-hole formation zone with cement slurry is possible only in wells that hold a static level at the wellhead. In gas wells with abnormally low reservoir pressures, the static level drops below the wellhead. The implementation of this control becomes possible if, during the filling of the fracture zone with the borehole, the liquid level rises to the mouth. This requires the use of an excess volume of cement slurry compared to the volume of the fracture zone. If the level does not rise to the mouth, control is impossible, and the process of filling the borehole is uncontrollable. In both cases, it is possible to break through the squeezing or flushing fluid through the grout, delivered to the borehole cavity. In this case, a through channel is formed, and the destroyed bottom-hole zone remains unrestored. The method involves a special preliminary operation of killing the well, which increases the duration of the overhaul, and also reduces the initial productivity of the well.

The technical result that can be obtained by implementing the invention is reduced to the following:
increasing the efficiency and reliability of restoring the bottom-hole zone of the formation while simultaneously isolating the annular water inflow while maintaining the reservoir properties of the formation by creating an integral stone of selective permeability in the destroyed annular space, increasing the completeness of filling the cavity in the annular space with grouting fluid, reducing the dilution of the latter with formation water and vending fluid;
improved operational characteristics of the system "restored bottom-hole formation zone-well" by cleaning the perforation holes of the production string and increasing the filtration area behind them;
increases the security of the implementation of the method due to the ability to control the process;
the duration of the overhaul of the well is reduced due to the simultaneous work on the restoration of the bottom-hole zone of the formation and isolation of annular water inflow, the exclusion of the preliminary operation of killing.

где V_{n НТР} - объем порции НТР, м³;
Р_{заб доп} - максимально допустимое забойное давление в скважине, Па;
S_НКТ - площадь внутритрубного пространства НКТ, м²;
ρ_НTР- плотность НТР, кг/м³;
q - ускорение свободного падения, м/с²,
или объема всего приготовленного НТР и порции продавочной жидкости, объем которой рассчитывают по формуле

где V_{п пж} - объем порции продавочной жидкости, м³;
V_НТР - объем всего приготовленного НТР, м³;
ρ_пж - плотность продавочной жидкости, кг/м³,
с его максимально допустимой величиной, предварительно определяемой по формуле

где Р_{у зп} - максимально допустимое устьевое давление в заколонном пространстве НКТ, Па;
S_зп - площадь заколонного пространства НКТ, м²;
V_НТР - текущий объем закаченного НТР, м³;
V_пж - текущий объем закаченной продавочной жидкости, м³,
причем при достижении текущего значения устьевого давления газа в заколонном пространстве НКТ его максимально допустимой величины стравливают газ из заколонного пространства НКТ с темпом, рассчитываемым по формуле

где ΔP_{у зп}(t) - темп стравливания газа из заколонного пространства НКТ, Па/с;
Q - подача насоса, м³/с,
до момента окончания закачивания и продавливания НТР, при недостижении текущего значения устьевого давления газа в заколонном пространстве НКТ его максимально допустимой величины после окончания продавливания НТР закачивают техническую воду в заколонное пространство НКТ с одновременным контролем устьевого давления в колонне НКТ до достижения текущего значения устьевого давления в колонне НКТ величины, определяемой по формуле

где Р_{у НКТ} - максимально допустимое устьевое давление в колонне НКТ при закачивании продавочной жидкости в заколонное пространство НКТ, Па;
L_НКТ - глубина спуска НКТ, м;
h_НТР - высота столба НТР, оставляемого в колонне НКТ в момент окончания продавливания НТР, м,
а глушение скважины производят после продавливания НТР одновременно с вымыванием излишков НТР из колонны НКТ и заколонного пространства НКТ путем закачивания продавочной жидкости в колонну НКТ с одновременным регулированием давления в колонне НКТ посредством стравливания газожидкостной смеси из заколонного пространства НКТ с темпом роста устьевого давления в колонне НКТ, определяемым по формуле

где ΔP_{у НКT}(t) - темп роста устьевого давления в колонне НКТ, Па/с,
до величины максимально допустимого устьевого давления в колонне НКТ в момент полного вымывания НТР из колонны НКТ, определяемой по формуле
P_{у НКT1}= P_{заб доп} - ρ_пж•q•L_НКТ,
где Р_{у НКТ1} - максимально допустимое устьевое давление в колонне НКТ в момент полного вымывания НТР из колонны НКТ, Па,
а вымывание излишков НТР из заколонного пространства НКТ осуществляют при постоянном достигнутом максимально допустимом устьевом давлении в колонне НКТ, после чего удаляют стакан из эксплуатационной колонны до нижней границы интервала перфорации вымыванием и очищают зумпф. Причем преимущественно готовят НТР следующего состава, мас.ч.:
Тампонажный портландцемент - 100
Древесные опилки - 5-8
Кальцинированная сода - 3-10
Поливиниловый спирт - 0,8-0,9
Дизельное топливо - 44-56
Вода - 59-82
Для эксплуатации газоносных коллекторов и пластов резервуаров подземного хранилища газа (ПХГ), представленных чередованием неоднородных газо-водоносных и глинистых пропластков используют скважины с закрытой конструкцией забоя. Продуктивный комплекс полностью разбуривают, обсаживают эксплуатационной колонной, которую цементируют в нем и перфорируют. Длительная эксплуатация скважин в форсированном режиме приводит к разрушению коллектора в призабойной зоне пласта и цементного камня вокруг эксплуатационной колонны. В результате выноса породы в призабойной зоне пласта образуются каверна и суффозионные каналы, уходящие вглубь коллектора. Продукты разрушения поступают в ствол скважины, формируют песчано-глинистые пробки вплоть до полного перекрытия интервала перфорации и закупорки НКТ. Разрушенный цементный камень вокруг эксплуатационной колонны является каналом для заколонного водопритока, интенсифицирующего разрушение коллектора в призабойной зоне пласта и приводящего к самоглушению скважины. Вибрация незакрепленной обсадной колонны при движении газа и воды приводит к ее разрушению. Капитальный ремонт таких скважин должен заключаться в восстановлении разрушенной призабойной зоны пласта. Для этого зону разрушения - каверну, суффозионные каналы и очищенное кольцевое пространство - заполняют НТР, образующим после затвердения целостный камень, проницаемый для газа, но непроницаемый для воды. При этом высокая вязкость НТР исключает его проникновение в поровое пространство породы, что сохраняет исходные коллекторские свойства пласта. Сформировавшийся камень обладает избирательной проницаемостью, по всей монолитной структуре исключает поступление пластовой воды в скважину, в том числе и заколонного водопритока. Наличие целостного газопроницаемого камня в восстановленной призабойной зоне пласта приводит к перераспределению градиентов давления и скоростей радиальной фильтрации газа. Максимальные градиенты, возникающие в области, прилегающей к зоне разгрузки фильтрационного потока газа, перемещаются со стенок каверны в область камня. Большая площадь фильтрации по наружной поверхности камня снижает указанные градиенты в прилегающем к нему коллекторе. Значительная механическая прочность проницаемого камня позволяет ему выдерживать градиенты давления и скоростей без разрушения при увеличении эксплуатационной депрессии на пласт. При этом в пласте-коллекторе развиваются градиенты, недостаточные для его разрушения, т.е. обеспечиваются условия для безаварийного повышения дебита скважины. Одновременно прочный проницаемый камень закрепляет свод прискважинной каверны, что предотвращает его обрушение и кольматацию интервала перфорации, а также саму эксплуатационную колонну в каверне, что исключает ее разрушение от вибрации. Тем самым обеспечивается надежность предлагаемого способа. Повышение эффективности и надежности восстановления призабойной зоны пласта с одновременной изоляцией заколонного водопритока обеспечивает и полнота заполнения каверны в заколонном пространстве при продавливании НТР исходной растекаемости в очищенную зону разрушения при максимально допустимом забойном давлении в скважине. По предполагаемому способу прискважинную зону разрушения очищают от дезагрегированных частиц горной породы (коллектора и покрышки) цементного камня. Для этого отбирают газ по колонне НКТ с постепенным повышением депрессии на пласт до начала выноса пластовой воды. Газоводяная смесь промывает суффозионные каналы в пласте и каналы разрушения в цементном камне. Дезагрегированные частицы выносятся в ствол скважины, где в зависимости от размеров выпадают в зумпф или транспортируются на поверхность. Далее призабойную зону пласта, включая каналы разрушения, осушают. Для этого по колонне НКТ закачивают газ, который оттесняет воду из каверны и суффозионных каналов в горной породе, порового пространства коллектора, а также из трещин в цементном кольце вдоль эксплуатационной колонны. Об окончании процесса осушки судят по достижению установившегося режима фильтрации. Таким образом создают условия для глубокого проникновения НТР по очищенным сухим каналам разрушения.The technical result is achieved using a known method, including the preparation of cement slurry, forming a gas-permeable stone after curing, pumping and forcing it through the tubing string with squeezing fluid through the perforation holes of the production string, killing the well, washing out excess cement slurry from the tubing string and tubing annulus, removing cups from the production casing to the lower boundary of the perforation interval, cleaning the sump, waiting for the curing to be grouted of solution, well completion, which are prepared nefteemulsionny backfill solution (STD), comprising water and a hydrocarbon liquid in a ratio by weight. hours, equal to 1: 0.63-0.83, and a mass ratio of liquid and solid phase of 1.04-1.26, forming both a gas-permeable and waterproof stone after curing, additionally take gas through the tubing string with a gradual increase in depression to the formation before the start of the removal of formation water, gas is pumped into the formation through the tubing string until a steady state of filtration is achieved, the well is stopped, the steady wellhead gas pressure in the tubing string and the annular space of the tubing is measured, gas current wellhead pressure is continuously monitored and in the annular space of the tubing during the pumping and forcing of the STR through the tubing string, the value of the latter from the moment of pumping a portion of the STR, the volume of which is calculated by the formula

where V _{n НТР} - volume of a portion of НТР, m ³ ;
P _{zab add} - the maximum allowable bottomhole pressure in the well, Pa;
S _tubing - the area of the tubing tubing, m ² ;
ρ _НТР - density of _НТР , kg / m ³ ;
q - acceleration of gravity, m / s ² ,
or the volume of all prepared NTR and a portion of the squeezing liquid, the volume of which is calculated by the formula

where V _{p pzh} - the portion size of the squeezing fluid, m ³ ;
V _NTR - the volume of all prepared NTR, m ³ ;
ρ _pzh - the density of the displacement fluid, kg / m ³ ,
with its maximum allowable value, previously determined by the formula

where P _{at sn} - the maximum allowable wellhead pressure in the annular space of the tubing, Pa;
S _sn - the area of the annular space of the tubing, m ² ;
V _NTR - the current volume of injected NTR, m ³ ;
V _pzh - the current volume of pumped squeezing fluid, m ³ ,
moreover, when the current value of the wellhead pressure of the gas in the annular space of the tubing is reached, its maximum permissible value is released from the annular space of the tubing with a pace calculated by the formula

where ΔP _{at sn} (t) is the rate of gas release from the annular space of the tubing, Pa / s;
Q - pump flow, m ³ / s,
until the end of pumping and forcing of the STR, when the current value of the wellhead pressure of the gas in the annular space of the tubing is not reached its maximum permissible value after the end of the pushing of the STR, technical water is pumped into the annulus of the tubing with simultaneous monitoring of the wellhead pressure in the tubing string until the current value of the wellhead pressure in the string is reached Tubing value determined by the formula

where P _{at the tubing} is the maximum allowable wellhead pressure in the tubing string when pumping squeezing fluid into the annular space of the tubing, Pa;
L _tubing - the depth of the tubing, m;
h _NTR - the height of the column of NTR left in the tubing string at the end of the pushing of the NTR, m,
and killing a well is carried out after pushing the STR along with washing out the excess STR from the tubing string and the annulus of the tubing by pumping the squeezing fluid into the tubing string while simultaneously regulating the pressure in the tubing string by bleeding the gas-liquid mixture from the annulus of the tubing with an increase in wellhead pressure in the tubing string, determined by the formula

where ΔP _{at NKT} (t) is the growth rate of wellhead pressure in the tubing string, Pa / s,
to the value of the maximum allowable wellhead pressure in the tubing string at the time of complete washing out of the STR from the tubing string, determined by the formula
P _{at NKT1} = P _{zab add} - ρ _pzh • q • L _tubing ,
where P _{at tubing1} is the maximum allowable wellhead pressure in the tubing string at the time of complete leaching of the STR from the tubing string, Pa,
and the washing out of the excess NTR from the annular space of the tubing is carried out at a constant maximum achievable wellhead pressure in the tubing string, then the glass is removed from the production string to the lower boundary of the perforation interval by washing and the sump is cleaned. And predominantly prepare the STR the following composition, parts by weight:
Grouting Portland cement - 100
Sawdust - 5-8
Soda Ash - 3-10
Polyvinyl alcohol - 0.8-0.9
Diesel - 44-56
Water - 59-82
For operation of gas-bearing reservoirs and reservoir reservoirs of the underground gas storage (UGS), represented by the alternation of heterogeneous gas-water and clay interlayers, wells with a closed bottom structure are used. The productive complex is completely drilled, cased with a production string, which is cemented in it and perforated. Long-term operation of wells in forced mode leads to the destruction of the reservoir in the bottomhole formation zone and cement stone around the production string. As a result of the removal of the rock in the bottom-hole zone of the formation, a cavity and suffusion channels are formed, extending deep into the reservoir. Fracture products enter the wellbore and form sand-clay plugs up to the complete overlap of the perforation and plugging of the tubing. The destroyed cement stone around the production string is a channel for annular water inflow, intensifying the destruction of the reservoir in the bottom-hole formation zone and leading to self-suppression of the well. Vibration of an unsecured casing during the movement of gas and water leads to its destruction. Overhaul of such wells should consist in restoration of the destroyed bottom-hole zone of the formation. For this, the destruction zone — a cavity, suffusion channels, and a cleaned annular space — is filled with NTR, which, after hardening, forms an integral stone that is permeable to gas but impermeable to water. At the same time, the high viscosity of the NTR excludes its penetration into the pore space of the rock, which preserves the initial reservoir properties of the formation. The formed stone has selective permeability; it eliminates the inflow of formation water into the well throughout the monolithic structure, including annular water inflow. The presence of an integral gas-permeable stone in the restored bottomhole formation zone leads to a redistribution of pressure gradients and radial gas filtration rates. The maximum gradients arising in the region adjacent to the discharge zone of the gas filtration stream move from the walls of the cavity to the stone region. A large filtration area on the outer surface of the stone reduces these gradients in the adjacent collector. Significant mechanical strength of the permeable stone allows it to withstand pressure and velocity gradients without breaking with increasing operational depression on the formation. At the same time, gradients insufficient for its destruction develop in the reservoir, i.e. Provides conditions for a trouble-free increase in well production. At the same time, a strong permeable stone secures the arch of the borehole cavity, which prevents its collapse and the mudding of the perforation interval, as well as the production casing itself in the cavity, which excludes its destruction from vibration. This ensures the reliability of the proposed method. Increasing the efficiency and reliability of restoring the bottom-hole zone of the formation with simultaneous isolation of the annular water inflow also ensures the completeness of filling the cavity in the annular space while forcing the NTR of the initial spreadability into the cleaned fracture zone at the maximum allowable bottomhole pressure in the well. According to the proposed method, the borehole fracture zone is cleaned of disaggregated rock particles (collector and tire) of cement stone. To do this, gas is taken from the tubing string with a gradual increase in depression on the formation before the start of formation water removal. The gas-water mixture flushes the suffusion channels in the formation and the destruction channels in the cement stone. Disaggregated particles are carried into the wellbore, where, depending on their size, they fall into the sump or transported to the surface. Next, the bottomhole formation zone, including fracture channels, is drained. To do this, gas is pumped through the tubing string, which displaces water from the cavity and suffusion channels in the rock, the pore space of the reservoir, as well as from cracks in the cement ring along the production string. The completion of the drying process is judged by the achievement of a steady state filtration. Thus, conditions are created for the deep penetration of STR through the cleaned dry destruction channels.

 The filling of the borehole fracture zone of the NTR is carried out without mixing it with squeezing liquid and produced water. For this, NTR is pumped through the tubing string into a drained, gas-filled well. As a result, conditions are created for the complete filling of the fracture zone with integral grouting material of selective permeability.

 After the column of NTR in the tubing string overcomes the steady-state gas pressure in the well, it begins to flow to its bottom due to gravity. At the same time, the gas displaced from the tubing string is filtered into the formation through the perforation holes of the production string. As the NTR of the downhole fracture zone is filled, its level in the well rises. After the perforation openings of the production casing are blocked, gas filtration into the formation is stopped. Further supply of scientific and technological revolution during pumping and forcing through the tubing string leads to an increase in its level in the annular space of the tubing and gas compression in it. NTR enters the destroyed bottom-hole formation zone under the action of the total pressure of its column in the annular space of the tubing and gas above it. Thus, the squeezing fluid remains in the tubing string without falling into the borehole fracture zone.

 NTR is crushed into the fracture zone at the maximum bottomhole pressure in the well, preventing hydraulic fracturing. Monitoring the current bottomhole pressure in a gas-filled well while pumping and forcing SR through the tubing string by wellhead pressure in them is impossible, since it decreases uncontrollably until a vacuum occurs. Therefore, the control is carried out by the wellhead pressure of the gas in the annular space of the tubing. The growth of the specified pressure more than the value measured after the shutdown of the well (reservoir pressure) indicates the beginning of the increase in bottomhole pressure in the well. The achievement of the current wellhead gas pressure in the annular space of the tubing of its maximum allowable value indicates the development of the maximum allowable bottomhole pressure in the well. The maximum allowable value of the wellhead gas pressure in the annular space of the tubing is determined by the mathematical formula obtained on the basis of the balance of bottomhole pressures in the tubing string and their annular space, taking into account the volumes of the injected grouting fluid and squeezing fluid. In this case, the imaginary calculated values are eliminated after the creation in the tubing string of a liquid column (STR or STR and squeezing fluid), the pressure of which is equal to the maximum allowable bottomhole pressure.

 Failure to achieve the current wellhead pressure of the gas in the annulus of the tubing at its maximum permissible value at the time of completion of the injection and forcing of the STR indicates the undeveloped maximum permissible bottomhole pressure in the well. Downhole pressure is increased by additional gas compression in the annular space of the tubing by pumping technical water into it. In this case, process water also does not fall into the borehole destruction zone. The control of the current bottomhole pressure is carried out by wellhead pressure in the tubing string. Additionally compressible gas raises the pressure in the tubing to the maximum allowable value at the mouth, determined by the formula.

 After reaching the maximum allowable bottom-hole pressure, it is kept constant until completion of well killing and leaching of excess STR from the tubing string and its annulus. To do this, a liquid (NTR or squeezing liquid) is pumped into the tubing string with simultaneous bleeding of the gas or gas-liquid mixture from the annular space of the tubing. The proposed estimated rate of bleeding provides compensation for the increase in pressure of the composite column of the cement slurry and squeezing fluid in the annular space of the tubing. Thus, they prevent the destruction of the production casing and hydraulic fracturing, as well as the delivery of NTR into the well until the moment of its consistency increase.

 Removal of the glass from the production casing is carried out by washing it before the end of the setting time of the STR. This avoids cracking of the created permeable stone in the borehole zone due to the absence of vibration that occurs when the glass is drilled in the production casing after it is cured. At the same time, NTR is washed out of the perforation holes of the production string, which helps to improve the filtration characteristics of the system "restored bottom-hole formation zone - well". The above, along with constant monitoring of wellhead pressure using calculation formulas, increases the safety of the method. And killing a well at the same time as washing out the excess of scientific and technological progress also affects the reduction of time spent on work. Thus, the proposed combination of essential features provides the claimed technical result.

According to available sources, the following is known:
in the method of conducting insulating work in the well (see AS USSR 825858 from 05.17.74, class E 21 B 33/13, publ. OB 16, 1981) during the injection of the plugging mixture, a pressure change is recorded with the purpose of improving the control of the placement of the plugging mixture in a predetermined interval, in the method of processing the bottom-hole zone of wells that have opened a heterogeneous oil reservoir (see RF patent 2103494 from 09.30.96, class E 21 B 43/25, 43/12, publ. ABOUT 3, 1998) an agent is sequentially pumped into the bottom-hole zone of the formation, increasing the filtration resistance while increasing in time change the pressure at the bottom of the well from the reservoir at the beginning of the treatment to the maximum at the end of the treatment, and an agent that reduces the filtration resistance when the pressure decreases at the time of the bottom of the well from the maximum at the beginning of the treatment to the reservoir at the end of the treatment, and the maximum pressure is in another case, there should be less hydraulic fracturing pressure in order to increase the efficiency of processing the bottom-hole zone of the well, which revealed an oil reservoir that is heterogeneous in permeability and saturation by increasing selectivity of agents that reduce filtration resistance to low permeability layers of the bottomhole zone with significant residual oil reserves, and agents that increase filtration resistance to high permeability, intersected by cracks, watered, gassed layers of the reservoir; in the method of isolating aquifers in a well being drilled (see A.S. USSR 1747677 dated 04/20/1989 according to class E 21 B 33/13, publ. OB 26, 1992), gelling material is injected into the pipes through drill pipes all aquifers before the creation of excess pressure at the wellhead, determined by the formula with the aim of increasing the efficiency of the method when isolating several aquifers with different values of reservoir pressures, their height relative to each other and the distances between them, in the method of cementing a blind obsa columns (see AS of the USSR 1624126 of 02.22.89 according to class E 21 B 33/13, publ. OB 4, 1991) at the end of the forcing, the mouth is immediately closed, and the maximum pressure created due to the pressure difference of the liquid columns in the annular and pipe spaces, which is fixed in the annular space of the mouth, in order to improve the quality and ensure control of the cementing process, in the method of fixing and cementing wells (see AS USSR 1463905 from 04/13/87, cl . E 21 B 33/13, publ. ABOUT 9, 1989) before running the casing, hydraulic fracturing of the rocks above the reservoir and fixing the pressure at the wellhead in the annulus to improve the quality of cementing by increasing the completeness of filling the annulus of the wells with cement mortar and save cementing time;
in the method of pumping wells with weakly cemented reservoirs (see AS USSR 727838 dated 08.29.78 according to class E 21 B 33/138, 43/08, publ. ABOUT 14, 1980) the reservoir interval is plugged through drill pipes with a permeable grouting composition with a delayed setting time, selected taking into account the time spent on tripping and auxiliary operations in order to improve the quality of the filtration zone, in the method of isolating bottom water in oil wells (see RF patent 2128286 from 04/09/96 according to class E 21 B 43/32, 33/138, publ. OB 9, 1999) download projective water shutoff composition for forming an artificial screen impermeable and permeable part of the bottom part of the cone-shaped top of the oil-saturated liquid in order to extend the period of anhydrous well operation, reduction in the percentage of water production and extraction of the oil-saturated liquid portion of transition zone water - oil;
in the method of repairing the annulus of the well (see AS USSR 1832822 from 08/09/1989, class E 21 B 33/13, chipboard), the remnants of the cement slurry are washed out above the packer by creating a squeezing fluid over it to increase cost-effectiveness and quality of repair, in the method of installing a cement bridge in a well (see RF patent 2146756 dated 04/21/1999, class E 21 B 33/13, publ. ABOUT 8, 2000) the excess cement bridge is removed by the destruction of the cement stone by pumping flushing fluid with a flow rate of 6-8 l / s and a pressure of 45-50 atm in order to increasing the efficiency of the method of installing a cement bridge by preventing the absorption of cement mortar;
in the method of isolating the influx of formation water (see AS USSR 1609966 from 03.24.88 according to class E 21 B 33/13, published in OB 44, 1990), air is pumped to the established filtration mode, and plugging the composition is pumped in an air stream in an aerosol formation mode in order to increase the reliability of isolation of the water-producing formation by deeply impregnating the rocks adjacent to the walls of the well with a plug composition, in the method of isolating formation waters (see a.s. USSR 1021763 from 12.29.81, class E 21 33/138, published in OB 21, 1983) pump gas into the annulus until the moment until the pressure in it becomes equal to the reservoir, and after injection of the grout, the annulus of the well is communicated with the tubing in order to increase the efficiency of the isolation process by eliminating the absorption of the grout by the reservoir;
in a method for restoring tightness of casing strings (see AS USSR 825857 of 04.16.74, class E 21 B 33/13, publ. OB 16, 1981), before pumping the plugging solution, the liquid in the string is pumped to the bottom the boundaries of the leakage interval, after which this interval is drained by injecting compressed air in order to improve the quality of insulation work, in the method of installing cement bridges in absorbing wells (see AS USSR 1789662 from 02.28.90, class E 21 B 33 / 134, 33/13, published in OB 3, 1993) cement is injected into the well with a viscoelastic separator stvlyayut portions. Moreover, air or gas is injected between the first and second portions of the viscoelastic separator, the ratio between the volumes of the first and second portions of the cement mortar and the viscoelastic separator is selected proportionally to the ratio of the cross-sectional areas of the annulus and the internal cavity of the filling pipes, and the volume of injected air or gas is determined from the ratio in order to prevent formation absorption and increasing the accuracy of the separation bridge installation;
in a method of isolating annular gas flows (see RF patent 2126880 of 02.27.98, class E 21 B 33/13, publ. AB 6, 1999), the viscoelastic composition and cement mortar are pumped into the annulus through the gas-bearing part of the productive formation with a closed annular space, after which injection fluid is pumped into the volume of deflated tubing minus the injected volume of cement in an open annular space, release pressure on the mouth in order to increase the efficiency of isolation of annular gas flows ;
in the method of concreting oil and gas wells (see RF patent 2081299 dated 05.03.94, class E 21 B 33/14, publ. OB 16, 1997), cement slurry is used as a grouting solution, before which injection is carried out injection into the casing of water or air under pressure, followed by their discharge at a speed that ensures equal volumetric flow rates of discharged water or air from the casing and the injected concrete solution, which are controlled by a manometer - a vacuum gauge, while supporting concrete backpressure at the mouth th mixture by adjusting the discharge of water or air; in the method of cementing wells (see AS USSR 1439210 dated 01.29.1987 according to class E 21 B 33/13, published in OB 43, 1988) create backpressure in the annulus during the entire hardening time of grouting the solution by flushing through the silencing and fitting line in order to improve the cementing quality of offshore wells equipped with a preventer, by making it possible to remove fluids appearing on the underwater wellhead;
in the method of reverse cementing the casing string in the well (see RF patent 2086752 dated 02.15.95, class E 21 B 33/14, published in OB 22, 1997) after filling the annulus in the casing and flushing casing pipes with liquid in them create back pressure, while during the injection of grouting mortar into the well annulus on the flow line of the flushing pipe string, the back pressure is adjusted at the wellhead to reduce time and material costs and means for cementing the casing string in the wells while improving the quality of cementing in any mining and geological conditions by providing the ability to pump cement slurry of any density, at any feed rate and at any pressure in the annulus of a well with either low or high specific permeability of the intervals of its bore, eliminating the need to produce their preliminary isolation, in the method of cementing casing strings (see.with. USSR 1454953 dated March 31, 87 according to class E 21 B 33/14, publ. ABOUT 4, 1989) inject buffer fluid and cement slurry with backpressure at the wellhead, not less than the formation pressure, but less than the hydraulic fracture pressure, and during the cement grouting, the backpressure at the wellhead is released in accordance with the rate of increase in the selling pressure in order to reduce the intensity of absorption of the cement with absorbing layers;
in the method of killing a well (see RF patent 2136855 dated 01/05/1999, class E 21 B 43/12, publ. AB 25, 1999) water is pumped into the annular space of the well when the tubing string is closed at the mouth until stabilization pressure at the wellhead in a volume of not more than the volume of the well ... carry out a technological pause and bleed gas from the tubing string and annular space of the well in order to increase the efficiency of killing wells filled with gas, with the simultaneous effect of selective isolation of the flooded part of the formation and cleaning of the productive bottom-hole part fins from colmatants;
of interest is a method of strengthening the bottom-hole zone of a gas well, composed of weakly cemented reservoirs (see RF patent 2081296 from 08/10/95 according to class E 21 B 33/13, publ. OB 16, 1997), but this method is implemented only in wells with an open bottom structure, since the fixing composition is delivered to the walls of the bottom hole zone being treated by jets. In wells with a closed face design, these jets will be extinguished when passing through the perforation holes of the production string. In addition, the method does not allow to fix the arch of the cavity in the bottomhole zone, since only the previously expanded weakly cemented reservoir is strengthened and the water inflows are isolated.

 The analysis of the invented level allows us to conclude in accordance with the decision the condition of "inventive step".

Use oil emulsion cement slurries of the following composition, parts by weight:
Grouting Portland cement - 100
Sawdust - 5.4
Soda Ash - 3
Polyvinyl alcohol - 0.8
Diesel - 47.4
Water - 82
density 1360 kg / m ³ , flowability along the cone of the AzNII 17 cm, compressive strength of the stone after 3 days of hardening 0.98 MPa, gas permeability of the stone 0.311 μm ² , water permeability of the stone 0.0012 μm ² , water and hydrocarbon liquid in the ratio, wt. hours, 1: 0.65; mass ratio of liquid and solid phase 1.26;
Grouting Portland cement - 100
Sawdust - 6
Soda Ash - 4.9
Polyvinyl alcohol - 0.8
Diesel - 56
Water - 67
density 1340 kg / m ³ , spreadability on the cone of the AzNII 17 cm, compressive strength of the stone after 3 days of hardening 0.90 MPa, gas permeability of the stone 0.69 μm ² , water permeability of the stone 0.0089 μm ² , water and hydrocarbon liquid in the ratio wt. hours, 1: 0.83; mass ratio of liquid and solid phase 1.22;
Grouting Portland cement - 100
Sawdust - 8
Soda Ash - 4.9
Polyvinyl alcohol - 0.9
Diesel - 45.9
Water - 71.8
density 1320 kg / m ³ , spreadability along the cone of AzNII 15 cm, compressive strength of stone after 3 days of hardening 1.23 MPa, gas permeability of stone 0.63 μm ² , water permeability of stone 0.0044 μm ² , water and hydrocarbon liquid in the ratio, parts by weight, 1: 0.64; mass ratio of liquid and solid phase 1.14;
Grouting Portland cement - 100
Sawdust - 5.4
Soda Ash - 10
Polyvinyl alcohol - 0.8
Diesel - 47.4
Water - 75
density 1360 kg / m ³ , spreadability along the cone of AzNII 16.5 cm, compressive strength of the stone after 3 days of hardening 1.23 MPa, gas permeability of the stone 0.31 μm ² , water permeability of the stone 0.0065 μm ² , water and hydrocarbon liquid ratio, parts by weight, 1: 0.63; mass ratio of liquid and solid phase 1.26;
Grouting Portland cement - 100
Sawdust - 5
Soda Ash - 9.4
Polyvinyl alcohol - 0.9
Diesel - 44
Water - 59
density 1290 kg / m ³ , spreadability on the cone of the AzNII 17 cm, compressive strength of the stone after 3 days of hardening 1.35 MPa, gas permeability of the stone 0.36 μm ² , water permeability of the stone 0.0076 μm ² , water and hydrocarbon liquid in the ratio, wt. hours, 1: 0.65, the mass ratio of liquid and solid phase is 1.04.

 PCT II-100 grouting portland cement is used in accordance with GOST 1581-96, soda ash in accordance with GOST 83-79, PVA 18/11 polyvinyl alcohol in accordance with GOST 10779-78, diesel fuel in accordance with TU 305-82, wood chips with a particle size of not more than 2 mm in accordance with GOST 18320-78.

 The effect of the above solutions is equivalent.

The content in the solution:
sawdust less than 5 wt.h. does not increase the permeability of the forming stone, and more than 8 parts by weight leads to a decrease in spreadability below technologically permissible and a decrease in the strength of the formed permeable stone;
soda ash less than 3 parts by weight increases the formation of permeable stone, and more than 10 wt.h. causes coagulation of grouting mortar, leading to an increase in its viscosity and a decrease in spreadability below the technologically permissible;
polyvinyl alcohol less than 0.8 wt.h. does not lead to the formation of an emulsion and a sedimentation-resistant cement slurry, and more than 0.9 wt.h. not economically feasible;
diesel fuel less than 44 wt.h. reduces the permeability of the forming stone, and more than 56 parts by weight reduces the mechanical strength of the forming stone.

 In more detail, the essence of the proposed method is described by the following examples.

EXAMPLE 1. The method is implemented during the overhaul of the well 302 of the North Stavropol UGS, embedded in the sediments of the green suite. Geological and technical characteristics of the well:
Intervals of occurrence of sediments of the green retinue by units, m:
I layer - 987-993
α layer - 993-999
II layer - 999-1012
Depth of descent of the production casing, m - 1035
Diameter of production casing, m - 0.168
The thickness of the wall of the production casing, m - 0,009
Production casing perforation interval, m - 986-994
Type of perforation - slotted with a slot size of 0.15 x 0.005 m
Perforation density, holes / linear meters - 28
The installation interval of the sand bridge in the production casing, m - 996-1023
Depth of descent of the tubing string, m - 984
The diameter of the tubing string, m - 0,073
The wall thickness of the tubing string, m - 0,0055
The area of the tubing tubing, m ² - 0.00302
The area of annular space of tubing, m ² - 0,01351
Maximum permissible bottomhole pressure in the well, MPa - 12.5
Type of Christmas tree fittings - AFC 3-65 x 210 according to GOST 13846-89
Connection of a well with a gas distribution point - through an individual gas pipeline
At the early stage of development, the deposits of the green retinue represented a single gas-bearing complex, after the depletion of which the II layer was flooded, and the I layer began to be used as an underground storage tank.

After 8 cycles of gas injection-sampling, signs of destruction of the bottom-hole zone of the formation and the occurrence of annular water inflows from the II formation began to appear:
in the sump of the well, a sand-clay plug formed from a depth of 994 m;
at a gas flow rate of 130 thousand nm ³ / day, an increase in formation water removal to 50 m ³ / day was observed and the well was self-muffled;
while the gas flow rate was limited to 55 thousand m ³ / day, the well was prematurely flooded and went out of operation at the beginning of the second third of the gas extraction cycle.

 To carry out the overhaul of the well, an A-50M lifting unit is mounted on it.

 Gas is taken from the tubing string with a gradual increase in depression on the formation due to an increase in the diameter of the wellhead fittings before the start of the formation water removal. An increase in the depression on the formation is judged by a decrease in the wellhead pressure of the gas in the annular space of the tubing, which is measured by the MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain. Gas and water flow rates are measured at a gas distribution point.

With a wellhead nozzle diameter of 0.008 m, the wellhead pressure of the gas in the annulus of the tubing is 7.2 MPa, and dry gas is taken from the well with a flow rate of 80 thousand m ³ / day.

With a wellhead nozzle diameter of 0.01 m, the wellhead pressure of the gas in the annulus of the tubing is 7.1 MPa and dry gas is taken from the well with a flow rate of 90 thousand m ³ / day.

With a wellhead nozzle diameter of 0.012 m, the wellhead pressure of the gas in the annulus of the tubing is 6.9 MPa, and dry gas is taken from the well with a flow rate of 100 thousand m ³ / day.

With a wellhead nozzle diameter of 0.014 m, the wellhead pressure of the gas in the annulus of the tubing is 6.8 MPa and formation water is removed from the well with increasing flow rate from 0.9 m ³ / day with a gas flow rate of 110 thousand tons. m ³ / day

 Gas withdrawal is stopped and gas is pumped into the reservoir through the tubing string until a steady state filtration is achieved. Gas is supplied from a gas distribution point. The mode of gas filtration in the formation is judged by the wellhead pressure of the gas in the tubing string, which is measured by an MP-4U pressure gauge with a measuring range of 16 MPa installed on the fountain valves, and the gas flow rate, which is measured at the gas distribution point.

The initial gas injection pressure is 8.2 MPa at the mouth of the tubing string with a gas flow rate of 165 thousand m ³ / day.

Further, the gas injection pressure is 8.4 MPa at the mouth of the tubing string with an increase in gas flow to 175 thousand m ³ / day.

 At the last indicated characteristics, gas injection stabilizes, which indicates the achievement of a steady state filtration.

 Stop the well to measure steady wellhead gas pressure in the tubing string and tubing annulus. These pressures stabilized at a value of 7.6 MPa.

 Rebind fountain fittings. Fountain fittings are disconnected from the gas pipeline connecting the well with the gas distribution point. The output of the fountain fittings associated with the tubing string is tied with two cementing units designed for pumping grouting mortar and squeezing fluid. The outlet of the fountain fittings associated with the annular space of the tubing is tied up with a cementing unit ЦА-320М, intended for pumping squeezing fluid into it, and an adjustable throttle ДР-50 х 21 К2 equipped with a flare line.

To push through the STR, killing the well and washing out the excess STR from the tubing string and the annular space of the tubing use industrial water with a density of 1000 kg / m ³ .

где L_НКТ - глубина спуска колонны НКТ, м.To restore the bottom-hole zone of a gas well formation, NTR is used, forming both a gas-permeable and waterproof stone after curing:
The density of the cement slurry, kg / m ³ - 1360
Spreading of grouting mortar along the cone of AzNII, cm - 17
The stone compressive strength after 3 days of hardening, MPa - 0.98
The gas permeability of the stone, μm ² - 0.311
The permeability of the stone, μm ² - 0.0012
The maximum technologically permissible volume of NTR V _{NTR max} is determined from the conditions for the development of the maximum allowable bottomhole pressure when washing out the entire volume of NTR in the annular space of the tubing. He makes up

where L _tubing - the depth of descent of the tubing string, m

Based on the total delivered volume of the destruction products of the collector and cement stone, take and prepare NTR in the volume of V _NTR = 6 m ³ .

In the measuring unit of the cementing unit, the grouting fluid of the cement slurry is prepared by hydraulic stirring 1.7 m ³ (51 parts by weight) of industrial water, 101 kg (3 parts by weight) of soda ash, 0.7 m ³ (0.8 parts by weight) dry matter and 31 parts by weight of water) an aqueous solution of polyvinyl alcohol PVA 18/11 and 2 m ³ (47 parts by weight) of diesel fuel.

The cement-mixing machine 2СМН-20 shuts 3420 kg (100 parts by weight) of the cement portland cement PCT II-100, from where it enters a container with a volume of 9 m ³ .

 With continuous hydraulic stirring, 186 kg (5.4 parts by weight) of sawdust with a dispersion of not more than 2 mm are introduced into the solution.

 At the same time, the measuring tanks of all cementing units connected with fountain fittings are filled with technical water.

At the end of the preparation of the NTR, it is pumped into the tubing string with a pump flow rate of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump sleeve diameter of 0.115 m. installed on the fountain.

Figure 1 presents graphs of changes in the current values of the wellhead pressure of the gas in the annular space of the tubing and its maximum allowable value when pumping and forcing the STR through the tubing string. The ordinate axis corresponds to the indicated wellhead gas pressures in the annular space of the tubing (MPa). The abscissa axis corresponds to the total volume of NTR and squeezing fluid pumped into the tubing string (m ³ ). Line 1 corresponds to the maximum permissible values of wellhead gas pressure in the annular space of the tubing. The dotted part of line 1 corresponds to the imaginary values of the indicated values that occur when the calculated portion of STR is pumped into the volume V _{p of STR} . Line 2 corresponds to the current wellhead gas pressure in the annular space of the tubing. Point C corresponds to the moment the current wellhead pressure of the gas in the annular space of the tubing reaches its maximum permissible value and is the beginning of the venting of gas from the annular space of the tubing.

After injection of the 1st m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 7.6 MPa.

After the injection of the 2nd m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 7.6 MPa.

текущее устьевое давление газа в заколонном пространстве НКТ составляет 7,8 МПа. Начало повышения этого давления свидетельствует о практически полном заполнении каверны и скважины до верхних перфорационных отверстий. Сравнивают значение последнего с его максимально допустимой величиной, предварительно определенной по формуле

Так как текущее устьевое давление газа в заколонном пространстве НКТ не достигает его максимально допустимой величины, закачивание НТР продолжают. После закачивания 4-го м³ НТР текущее устьевое давление газа в заколонном пространстве НКТ 8,1 МПа, которое не достигает его максимально допустимой величины, предварительно определенной по формуле

ввиду чего закачивание НТР продолжают.After pumping a portion of NTR in the volume

the current wellhead gas pressure in the annular space of the tubing is 7.8 MPa. The beginning of the increase in this pressure indicates the almost complete filling of the cavity and the well to the upper perforations. The value of the latter is compared with its maximum allowable value, previously determined by the formula

Since the current wellhead pressure of the gas in the annular space of the tubing does not reach its maximum permissible value, pumping of the scientific and technological revolution continues. After injection of the 4th m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.1 MPa, which does not reach its maximum allowable value, previously determined by the formula

in view of which the pumping of NTR continues.

ввиду чего закачивание НТР продолжают.After injection of the 5th m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa, which does not reach its maximum allowable value, previously determined by the formula

in view of which the pumping of NTR continues.

Затем осуществляют продавливание НТР по колонне НКТ технической водой в объеме
V_пж = (L_НКТ-l_НТР)•S_НКТ,
где l_НТР - высота столба НТР, оставляемого в колонне НКТ на момент окончания продавливания НТР, м,
V_пж = (984-100)•0,00302 = 2,7 м³.After pumping in the 6th m ^{3 of} NTR (the total volume prepared), the current wellhead pressure of the gas in the annular space of the tubing is 8.4 MPa, which does not reach its maximum allowable value, previously determined by the formula

Then carry out the pushing of the STR along the tubing string with technical water in the amount
V _pzh = (L _tubing -l _STR ) • S _tubing ,
where l _NTR is the height of the column of NTR left in the tubing string at the end of the pushing of the NTR, m,
V _pzh = (984-100) • 0.00302 = 2.7 m ³ .

Так как текущее устьевое давление газа в заколонном пространстве НКТ достигает его максимально допустимой величины, стравливают газ из заколонного пространства НКТ с темпом

до момента окончания продавливания НТР. Указанный темп стравливания задают степенью открытия регулируемого дросселя ДР-50 х 21К2. Производят глушение скважины с одновременным вымыванием излишков НТР из колонны НКТ и заколонного пространства НКТ путем закачивания технической воды в колонну НКТ с подачей насоса 0,0041 м³/с с одновременным стравливанием газожидкостной смеси из заколонного пространства НКТ. Для вымывания излишков НТР из колонны НКТ в нее закачивают техническую воду в объеме
V_пж1=L_НТР•S_НКТ=100•0,00302=0,3м³.Pressing is carried out with a pump feed of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump sleeve diameter of 0.115 m. After pumping 0.8 m ^{3 of} displacement fluid, the current wellhead gas pressure in the annular space of the tubing is 8.8 MPa, and its maximum allowable value, predefined by the formula is

Since the current wellhead pressure of the gas in the annular space of the tubing reaches its maximum permissible value, the gas is vented from the annular space of the tubing with a pace

until the end of the pushing of the STR. The indicated rate of release is set by the degree of opening of the adjustable choke DR-50 x 21K2. Well killing is performed with the simultaneous leaching of excess NTR from the tubing string and tubing annulus by pumping technical water into the tubing string with a pump feed of 0.0041 m ³ / s while simultaneously bleeding the gas-liquid mixture from the tubing annulus. To wash excess STR from the tubing string, industrial water is pumped into it in a volume
V _pzh1 = L _NTR • S _tubing = 100 • 0.00302 = 0.3m ³ .

Темп роста устьевого давления в колонне НКТ задают степенью открытия регулируемого дросселя ДР-50 х 21К2 и поддерживают на уровне

Для вымывания излишков НТР из заколонного пространства НКТ в колонну НКТ закачивают техническую воду в объеме
V_пж2 = L_НКТ•S_зп = 984•0,01351 = 13,3 м³.At the same time, the wellhead pressure in the tubing string is increased to the value of the maximum allowable wellhead pressure in the tubing string at the time of the complete washing out of the STR from the tubing string, determined by the formula

The wellhead pressure growth rate in the tubing string is set by the degree of opening of the adjustable choke DR-50 x 21K2 and maintained at

To wash excess NTR from the annular space of the tubing, technical water is pumped into the tubing string in a volume
V _pzh2 = L _tubing • S _sn = 984 • 0.01351 = 13.3 m ³ .

At the same time, the value of the achieved maximum permissible wellhead pressure in the tubing string is maintained constant and equal to P _uNKT1 = 2.8 MPa, by changing the degree of opening of the adjustable choke DR-50 x 21K2.

Dismantle the fountain fittings. The tubing string is connected to the lead pipe with a square side of 0.112 m (TU 14-3-126-73) suspended through a swivel VE-50 on the hoist system of the A-50M lifting unit. Through the sleeve for washing boreholes 38-20000 MRTU 38-5-1465-67 the swivel is connected to the cementing unit CA-320M. When the pump feeds 0.0079 m ³ / s, corresponding to the operation of the cementing unit CA-320M in third gear with a pump bush diameter of 0.115 m, direct circulation of process water is restored.

 By lowering the tubing string with washing to a depth of 994 m, the lower boundary of the perforation interval, wash the glass from the STR and then sump in the range 994-996 m. The tubing string is raised to a depth of 984 m beyond the upper boundary of the perforation interval.

 Mount fountain fittings at the mouth.

 The well is left for a period of waiting for the curing of the cement slurry - 72 hours.

Tie up a fountain to develop the well. The outlet of the fountain fittings connected with the tubing string is tied up with a flare line, at the end of which a quick-change fitting with a diameter of 0.018 m is installed. In the measuring unit of the cementing unit, a foaming liquid is prepared by mixing 6 m ^{3 of} industrial water and 0.03 m ^{3 of a} 40% sulfonol solution (TU 6-01-1043-75). At the same time, a foaming liquid is injected into the annular space of the tubing with a flow of 0.0041 m ³ / s and compressed air with a flow rate of 9 m ³ / min. The beginning of the removal of foam from the well is obtained at wellhead pressure in the annular space of the tubing of 6.6 MPa. After the removal of foam and process water is stopped, the well is stopped and the fountain fittings are connected with a gas pipeline from the gas distribution point to take gas through the tubing string.

The operational characteristics of the well at the time of its withdrawal from overhaul are: at a wellhead nozzle diameter of 0.01, the gas production rate is 75 thousand n. m ³ / day, with a wellhead nozzle diameter of 0.012 m - a gas flow rate of 135 thousand m ³ / day, with a wellhead diameter of 0.014 m - a gas flow rate of 180 thousand mn m ³ / day, without signs of sand and water. Thus, the anhydrous gas flow rate increased by 1.4 times, which indicates the successful restoration of the bottom-hole zone of the gas well formation.

EXAMPLE 2. The method is implemented during the overhaul of well 315 of the North Stavropol UGS, embedded in the deposits of the green suite. Geological and technical characteristics of the well:
Intervals of occurrence of sediments of the green retinue by units, m:
I layer - 994-1000
α layer - 1000-1006
II layer - 1006-1018
Depth of descent of the production casing, m - 1038
The thickness of the wall of the production casing, m - 0,012
Production casing perforation interval, m - 994-1003
Type of perforation - slotted with a slot size of 0.15 x 0.005 m
Perforation density, holes / linear meters - 28
The installation interval of the sand bridge in the production casing, m - 1009-1028
The depth of descent of the tubing string, m - 992
The diameter of the tubing string, m - 0.114
The tubing string wall thickness, m - 0.007
The area of the tubing tubing, m ² - 0,00785
The area of annular space of tubing, m ² - 0,00608
Maximum permissible bottomhole pressure in the well, MPa - 12.5
Type of Christmas tree fittings - AFC 3-65 x 210 according to GOST 13846-89
Connection of a well with a gas distribution point - through an individual gas pipeline
At the early stage of development, the deposits of the green retinue represented a single gas-bearing complex, after the depletion of which the II layer was flooded, and the I layer began to be used as an underground storage tank.

After 15 cycles of gas injection-sampling, signs of destruction of the bottom-hole zone of the formation and the occurrence of annular water inflows from the second layer began to appear:
observed removal of formation sand and debris of cement stone with an intensity of up to 0.05 m ³ / day;
sand-clay plugs from a depth of 999 and 992 m, respectively, were formed twice in the wellbore;
at a gas flow rate of 120 thousand nm ³ / day, an increase in formation water removal to 24.5 m ³ / day was observed and the well was self-muffled;
while the flow rate was limited to 60 thousand nm ³ / day, the well was prematurely flooded and went out of operation in the middle and second third of the gas extraction cycle.

 To carry out the overhaul of the well, an A-50M lifting unit is mounted on it.

 Gas is taken from the tubing string with a gradual increase in depression on the formation due to an increase in the diameter of the wellhead fittings before the start of the formation water removal. An increase in the depression on the formation is judged by a decrease in the wellhead pressure of the gas in the annular space of the tubing, which is measured by the MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain. Gas and water flow rates are measured at a gas distribution point.

With a wellhead nozzle diameter of 0.008 m, the wellhead pressure of the gas in the annulus of the tubing is 6.6 MPa, and dry gas with a flow rate of 60 thousand m ³ / day is taken from the well.

With a wellhead nozzle diameter of 0.01 m, the wellhead pressure of the gas in the annulus of the tubing is 6.5 MPa, and dry gas is taken from the well with a flow rate of 80 thousand m ³ / day.

With a wellhead nozzle diameter of 0.012 m, the wellhead pressure of the gas in the annulus of the tubing is 6.4 MPa and formation water is removed from the well with increasing flow rate of 0.5 m ³ / day with a gas flow rate of 95 thousand tons. m ³ / day

 Gas withdrawal is stopped and gas is pumped into the reservoir through the tubing string until a steady state filtration is achieved. Gas is supplied from a gas distribution point. The mode of gas filtration in the formation is judged by the wellhead pressure of the gas in the tubing, which is measured by an MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain valves, and the gas flow rate, which is measured at the gas distribution point.

The initial gas injection pressure is 7.6 MPa at the mouth of the tubing string with a gas flow rate of 135 thousand m ³ / day.

Further, the gas injection pressure is 7.7 MPa at the mouth of the tubing string with an increase in gas flow to 210 thousand m ³ / day.

 At the last indicated characteristics, gas injection stabilizes, which indicates the achievement of a steady state filtration.

 Stop the well to measure steady wellhead gas pressure in the tubing string and tubing annulus. The indicated pressures stabilized at a value of 7 MPa.

 Rebind the fountain reinforcement according to the scheme described in example 1.

 To restore the bottom-hole zone of a gas well formation, NTR is used, which forms both a gas-permeable and waterproof stone after curing. The formulation and characteristics of the STR and the stone are similar to those specified in example 1.

For pushing STR, killing the well and for washing out excess STR from the tubing string and annular space of the tubing use industrial water with a density of 1000 kg / m ³ .

Исходя из суммарного вынесенного объема продуктов разрушения коллектора и цементного камня, принимают и приготавливают НТР в объеме V_НТР=2,5 м³.The maximum technological permissible volume of NTR V _{NTR max} is determined from the conditions for the development of the maximum permissible bottomhole pressure when leaching the entire volume of NTR in the annular space of the tubing

Based on the total delivered volume of the destruction products of the collector and cement stone, NTR is taken and prepared in the volume of V _NTR = 2.5 m ³ .

Prepare NTR in a container of 3 m ³ using a technology similar to that described in Example 1. To prepare 2.5 m ^{3 of} NTR, 0.7 m ^{3 of} industrial water, 42 kg of soda ash, 0.3 m ^{3 of a} 4% aqueous solution of polyvinyl alcohol are used PVA 18/11, 0.8 m ^{3 of} diesel fuel, 3400 kg of grouting Portland cement PCT II-100, 78 kg of wood sawdust with a dispersion of not more than 2 mm.

 At the same time, the measuring tanks of all cementing units connected with fountain fittings are filled with technical water.

At the end of the preparation of the NTR, it is pumped into the tubing string with a pump flow rate of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump sleeve diameter of 0.115 m. installed on the fountain. Figure 2 presents graphs of changes in the current values of the wellhead pressure of the gas in the annular space of the tubing and its maximum allowable value when pumping and forcing the STR through the tubing string. Designations are the same as in Figure 1 except for the point C. The dashed part of the line 1 corresponds to an imaginary value of the maximum permissible quantities of wellhead gas pressure in the tubing-casing space arising when pumping total volume prepared STR and squeezing portions in volume V of liquid _{f RV} .

After injection of the 1st m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After injection of the 2nd m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After injection of 2.5 m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

They carry out the pushing of the scientific and technological revolution along the tubing string by pumping technical water into it
V _pzh = (992-50) • 0.00785 = 7.4 m ³ .

The grouting mortar is pressed through with a pump feed of 0.0041 m ³ / s, corresponding to the operation of the cementing unit ЦА-320М in second gear with a pump bush diameter of 0.115 m.

After injecting 1 m ^{3 of} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After injection of the 2nd m ^{3 of} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After the injection of the 3rd m ^{3 of the} squeezing liquid, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After injecting the 4th m ^{3 of the} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 7 MPa.

After injection of the 5th m ^{3 of the} squeezing liquid, the current wellhead pressure of the gas in the annular space of the tubing is 7.1 MPa. The beginning of the increase in this pressure indicates the almost complete filling of the cavity and the well to the upper perforations.

After pumping in the 6th m ^{3 of the} squeezing liquid, the current wellhead gas pressure in the annular space of the tubing is 7.3 MPa.

текущее устьевое давление газа в заколонном пространстве НКТ 7,4 МПа. Сравнивают значение последнего с его максимально допустимой величиной, предварительно определенной по формуле

Так как текущее устьевое давление газа в заколонном пространстве НКТ не достигает его максимально допустимой величины, закачивание продавочной жидкости продолжают.After pumping a portion of squeezing liquid in volume

current wellhead gas pressure in the annulus of tubing 7.4 MPa. The value of the latter is compared with its maximum allowable value, previously determined by the formula

Since the current wellhead pressure of the gas in the annular space of the tubing does not reach its maximum permissible value, pumping of the displacement fluid is continued.

Закачивание продавочной жидкости продолжают.After injection of the 7th m ^{3 of the} squeezing liquid, the current wellhead gas pressure in the annular space of the tubing is 7.5 MPa, which does not reach its maximum allowable value, previously determined by the formula

Squeezing pumping fluid continues.

Так как текущее устьевое давление газа в момент окончания продавливания НТР по колонне НКТ меньше его максимально допустимой величины, закачивают техническую воду в заколонное пространство НКТ с одновременным контролем устьевого давления в колонне НКТ.After pumping 7.4 m ^{3 of} displacement fluid, the current wellhead gas pressure in the annular space of the tubing is 7.5 MPa, and its maximum allowable value, previously determined by the formula, is

Since the current wellhead pressure of the gas at the time of termination of the pushing of the STR along the tubing string is less than its maximum allowable value, process water is pumped into the annulus of the tubing with simultaneous control of the wellhead pressure in the tubing string.

After pumping 2 m ^{3 of} squeezing fluid into the annular space of the tubing, the current value of the wellhead pressure in the tubing string increases to the calculated value
P _{at tubing} = 12.5 • 10 ⁶ -1000 • 9.81 • (992-50) -1360 • 9.81 • 50 = 2.1 MPa,
which corresponds to the achievement of the maximum allowable bottomhole pressure.

 Stop pumping squeezing fluid into the annular space of the tubing.

Well killing is performed with the simultaneous leaching of excess NTR from the tubing string and tubing annulus by pumping technical water into the tubing string with a pump feed of 0.0041 m ³ / s while simultaneously bleeding the gas-liquid mixture from the tubing annulus.

To wash excess STR from the tubing string, industrial water is pumped into it in a volume
V _pzh1 = 50 • 0.00785 = 0.4 m ³ .

At the same time, the wellhead pressure in the tubing string is increased to the value of the maximum allowable wellhead pressure in the tubing string at the time of the complete washing out of the STR from the tubing string, determined by the formula
P _{at tubing1} = 12.5 • 10 ⁶ -1000 • 9.81 • 992 = 2.8 MPa.

Для вымывания излишков НТР из заколонного пространства НКТ в колонну НКТ закачивают техническую воду в объеме
V_пж2 = 992•0,00608 = 6 м³.The wellhead pressure growth rate in the tubing string is set by the degree of opening of the adjustable choke DR-50 x 21K2 and maintained at

To wash excess NTR from the annular space of the tubing, technical water is pumped into the tubing string in a volume
V _pzh2 = 992 • 0.00608 = 6 m ³ .

At the same time, the value of the achieved maximum permissible wellhead pressure in the tubing string is maintained constant and equal to P _{at tubing} 1 = 2.8 MPa by changing the degree of opening of the adjustable choke DR-50 x 21K2.

 Dismantle the fountain fittings. The tubing string is connected to the cementing unit ЦА-320М for washing the cup and washing the sump, as in example 1.

When the pump feeds 0.0079 m ³ / s, corresponding to the operation of the cementing unit CA-320M in third gear with a pump bush diameter of 0.115 m, direct circulation of process water is restored.

 By lowering the tubing string with washing to a depth of 1003 m — the lower boundary of the perforation interval — the glass is washed out of the STR and then the sump is washed in the range of 1003-1009 m.

 The tubing string is raised to a depth of 992 m — beyond the upper boundary of the perforation interval.

 Mount fountain fittings at the mouth.

 The well is left for a period of waiting for the curing of the cement slurry - 72 hours.

A fountain reinforcement is tied up for well development, as in Example 1. In the measuring unit of the cementing unit CA-320M, a foaming liquid is prepared by mixing 5 m ^{3 of} industrial water and 0.025 m ^{3 of a} 40% sulfonal solution (TU 6-01-1043-75). At the same time, a foaming liquid is injected into the annular space of the tubing with a flow of 0.0041 m ³ / s and compressed air with a flow rate of 9 m ³ / min. The beginning of the removal of foam from the well is obtained at wellhead pressure in the annular space of the tubing 5.4 MPa. After the removal of foam and process water is stopped, the well is stopped and the fountain fittings are connected with a gas pipeline from the gas distribution point to take gas through the tubing string.

The operational characteristics of the well at the time of its withdrawal from overhaul are: at a wellhead nozzle diameter of 0.015 m, the gas production rate is 200 thousand m ³ / day without signs of sand and water development. Thus, the anhydrous gas flow rate increased 1.7 times, which indicates the successful restoration of the bottom-hole zone of the gas well formation.

EXAMPLE 3. The method is implemented during the overhaul of the well 201 of the North Stavropol UGS embedded in the deposits of the green suite. Geological and technical characteristics of the well:
Intervals of occurrence of sediments of the green retinue by units, m:
I layer - 1004-1010
α layer - 1010-1016
II layer - 1016-1028
Depth of descent of the production casing, m - 1049
Diameter of production casing, m - 0.168
The thickness of the wall of the production casing, m - 0,012
Production casing perforation interval, m - 998-1010
Type of perforation - slotted with a slot size of 0.15 x 0.005 m
Perforation density, holes / linear meters - 28
The installation interval of the sand bridge in the production casing, m - 1033-1047
Depth of descent of the tubing string, m - 995
The diameter of the tubing string, m - 0.114
The tubing string wall thickness, m - 0.007
The area of the tubing tubing, m ² - 0,00785
The area of annular space of tubing, m ² - 0,00608
Maximum permissible bottomhole pressure in the well, MPa - 12.5
Type of Christmas tree fittings - AFC 3-65 x 210 according to GOST 13846-89
Connection of a well with a gas distribution point - through an individual gas pipeline
At the early stage of development, the deposits of the green retinue represented a single gas-bearing complex, after the depletion of which the II layer was flooded, and the I layer began to be used as an underground storage tank.

After 15 cycles of injection and gas extraction, signs of destruction of the bottom-hole zone of the formation and the occurrence of casing water inflows from the second layer began to appear:
sand-clay plugs from a depth of 1012 and 1011 m, respectively, were formed twice in the sump of the well;
at a gas flow rate of 70 thousand nm ³ / day, an increase in formation water removal to 20 m ³ / day was observed and the well was self-muffled;
while the gas flow rate was limited to 50 thousand n.m ³ / day, the well was prematurely flooded and went out of operation in the second third of the gas extraction cycle.

 To carry out the overhaul of the well, an A-50M lifting unit is mounted on it.

 Gas is taken from the tubing string with a gradual increase in depression on the formation due to an increase in the diameter of the wellhead fittings before the start of the formation water removal. An increase in the depression on the formation is judged by a decrease in the wellhead pressure of the gas in the annular space of the tubing, which is measured by the MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain. Gas and water flow rates are measured at a gas distribution point.

With a wellhead nozzle diameter of 0.01 m, the wellhead pressure of the gas in the annulus of the tubing is 7.7 MPa and dry gas is taken from the well with a flow rate of 110 thousand n.m ³ / day.

With a wellhead nozzle diameter of 0.011 m, the wellhead pressure of the gas in the annulus of the tubing is 7.4 MPa and formation water is removed from the well with increasing flow rate from 0.24 m ³ / day, sand removal up to 50 g / hour with a gas flow rate of 140 thousand. n.m ³ / day

 Gas withdrawal is stopped and gas is pumped into the reservoir through the tubing string until a steady state filtration is achieved. Gas is supplied from a gas distribution point. The mode of gas filtration in the formation is judged by the wellhead pressure in the tubing, which is measured with an MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain valves, and the gas flow rate, which is measured at the gas distribution point.

The initial gas injection pressure is 8.2 MPa at the mouth of the tubing string at a gas flow rate of 120 thousand n.m ³ / day.

Further, the gas injection pressure is 8.4 MPa at the mouth of the tubing string with an increase in gas flow to 125 thousand n.m ³ / day.

 At the last indicated characteristics, gas injection stabilizes, which indicates the achievement of a steady state filtration.

 Stop the well to measure steady wellhead gas pressure in the tubing string and tubing annulus. These pressures stabilized at 8.2 MPa.

 Rebind the fountain reinforcement according to the scheme described in example 1.

 To restore the bottom-hole zone of a gas well formation, NTR is used, which forms both a gas-permeable and waterproof stone after curing. The formulation and characteristics of the STR and the stone are similar to those specified in example 1.

For pushing STR, killing the well and washing out the excess STR from the tubing string and annular space of the tubing using industrial water with a density of 1000 kg / m ³ .

Исходя из суммарного вынесенного объема продуктов разрушения коллектора и цементного камня, принимают объем НТР раствора V_НТР=4 м³.The maximum technologically permissible volume of NTR V V _{NTR max} is determined from the conditions for the development of the maximum allowable bottomhole pressure when leaching the entire volume of NTR in the annular space of the tubing

Based on the total delivered volume of the destruction products of the collector and cement stone, take the volume of NTR solution V _NTR = 4 m ³ .

NTR is prepared in a container with a volume of 4 m ³ according to a technology similar to that described in Example 1. For the preparation of 4 m ³ , 1.2 m ^{3 of} industrial water, 67 kg of soda ash, 0.5 m ^{3 of a} 4% aqueous solution of PVA polyvinyl alcohol 18 / are used. 11, 1.3 m ^{3 of} diesel fuel, 2300 kg of grouting Portland cement PCT II-100, 124 kg of sawdust with a particle size of not more than 2 mm.

 At the same time, the measuring tanks of all cementing units connected with fountain fittings are filled with technical water.

At the end of the preparation of the NTR, it is pumped into the tubing string with a pump flow rate of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump sleeve diameter of 0.115 m. installed on the fountain. Figure 3 presents graphs of changes in the current values of the wellhead pressure of the gas in the annular space of the tubing and its maximum allowable value when pumping and forcing the STR through the tubing string. Designations are the same in figure 1. The dashed part of the line 1 corresponds to an imaginary value of the maximum permissible quantities of wellhead gas pressure in the tubing-casing space arising when pumping total volume prepared STR and squeezing portions in volume V of liquid _{f pancreas.}

After injection of the 1st m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

After injection of the 2nd m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

After the injection of the 3rd m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

After the injection of the 4th m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

The pushing of the scientific and technological revolution along the tubing string is carried out by pumping technical water into it in a volume
V _pzh = (995-50) • 0.00785 = 7.4 m ³ .

The grouting mortar is pressed through with a pump feed of 0.0041 m ³ / s, corresponding to the operation of the cementing unit ЦА-320М in second gear with a pump bush diameter of 0.115 m.

After the injection of 1 m ^{3 of} squeezing fluid, the current wellhead pressure of the gas in the annular space of the tubing is 8.2 MPa.

After injection of the 2nd m ^{3 of} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

After the injection of the 3rd m ^{3 of the} squeezing liquid, the current wellhead pressure of the gas in the annular space of the tubing is 8.2 MPa.

After injection of the 4th m ^{3 of the} squeezing liquid, the current wellhead gas pressure in the annular space of the tubing is 8.2 MPa.

текущее устьевое давление газа в заколонном пространстве НКТ 8,6 МПа. Начало повышения этого давления свидетельствует о практически полном заполнении каверны и скважины до верхних перфорационных отверстий. Сравнивают значение последнего с его максимально допустимой величиной, предварительно определенной по формуле

Так как текущее устьевое давление газа в заколонном пространстве НКТ не достигает его максимально допустимой величины, закачивание продавочной жидкости продолжают.After pumping a portion of squeezing liquid in volume

current wellhead gas pressure in the annular space of the tubing is 8.6 MPa. The beginning of the increase in this pressure indicates the almost complete filling of the cavity and the well to the upper perforations. The value of the latter is compared with its maximum allowable value, previously determined by the formula

Since the current wellhead pressure of the gas in the annular space of the tubing does not reach its maximum permissible value, pumping of the displacement fluid is continued.

ввиду чего закачивание продавочной жидкости продолжают.After the injection of 5 m ^{3 of} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 8.9 MPa, which does not reach its maximum allowable value, previously determined by the formula

whereby pumping of the squeezing liquid continues.

ввиду чего закачивание продавочной жидкости продолжают.After the injection of 6 m ^{3 of} squeezing liquid, the current wellhead gas pressure in the annulus of the tubing is 9.6 MPa, which does not reach its maximum allowable value, previously determined by the formula

whereby pumping of the squeezing liquid continues.

Так как текущее устьевое давление газа в заколонном пространстве НКТ достигает его максимально допустимой величины, закачивание продавочной жидкости продолжают до момента окончания продавливания НТР по колонне НКТ с одновременным стравливанием газа из заколонного пространства НКТ с темпом

Указанный темп стравливания задают степенью открытия регулируемого дросселя ДР-50 х 21 К2.After pumping 6.2 m ^{3 of} displacement fluid, the current wellhead gas pressure in the annular space of the tubing is 9.8 MPa, and its maximum allowable value, previously determined by the formula, is

Since the current wellhead pressure of the gas in the annular space of the tubing reaches its maximum permissible value, pumping of the squeezing fluid is continued until the end of the pushing of the STR through the tubing string with simultaneous bleeding of gas from the annular space of the tubing at a rate

The indicated rate of bleeding is set by the degree of opening of the adjustable choke DR-50 x 21 K2.

Well killing is performed with the simultaneous leaching of excess NTR from the tubing string and tubing annulus by pumping technical water into the tubing string with a pump feed of 0.0041 m ³ / s while simultaneously bleeding the gas-liquid mixture from the tubing annulus.

To wash excess STR from the tubing string, industrial water is pumped into it in a volume
V _pzh1 = 50 • 0.00785 = 0.4 m ³ .

At the same time, the wellhead pressure in the tubing string is increased to the value of the maximum allowable wellhead pressure in the tubing string at the time of complete washing out of the STR from the tubing string, determined by the formula
P _{at tubing1} = 12.5 • 10 ⁶ -1000 • 9.81 • 995 = 2.7 MPa.

Для вымывания излишков НТР из заколонного пространства НКТ в колонну НКТ закачивают техническую воду в объеме
V_пж2=995•0,00608=6 м³.The wellhead pressure growth rate in the tubing string is set by the degree of opening of the adjustable choke DR-50 x 21K2 and maintained at

To wash excess NTR from the annular space of the tubing, technical water is pumped into the tubing string in a volume
V _pzh2 = 995 • 0.00608 = 6 m ³ .

At the same time, the value of the achieved maximum permissible wellhead pressure in the tubing string is maintained constant and equal to P _{at tubing} 1 = 2.7 MPa by changing the degree of opening of the adjustable choke DR-50 x 21K2.

 Dismantle the fountain fittings, connect the tubing string to the cementing unit ЦА-320М for washing the cup and washing the sump, as in example 1.

When the pump feed is 0.0079 m ³ / s, corresponding to the operation of the cementing unit CA-320M in the third feed with a pump sleeve diameter of 0.115 m, direct circulation of process water is restored.

 By lowering the tubing string with washing to a depth of 1010 m, the lower boundary of the perforation interval, the glass is washed out of the STR, and then the sump is washed in the range of 1010-1033 m.

 The tubing string is raised to a depth of 998 m — beyond the upper boundary of the perforation interval.

 Mount fountain fittings at the mouth.

 The well is left for a period of waiting for the curing of the cement slurry - 72 hours.

 Tie up fountain reinforcement for well development, as in example 1.

In the measuring unit of the cementing unit CA-320M, a foaming liquid is prepared by mixing 5.5 m ^{3 of} industrial water and 0.03 m ^{3 of a} 40% sulfonol solution (TU 6-01-1043-75). At the same time, a foaming liquid is injected into the annular space of the tubing with a flow of 0.0041 m ³ / s and compressed air with a flow rate of 9 m ³ / min. The beginning of the removal of foam from the well is obtained at wellhead pressure in the annular space of the tubing of 8.7 MPa. After the removal of foam and process water is stopped, the well is stopped and the fountain fittings are connected with a gas pipeline from the gas distribution point to take gas through the tubing string.

The operational characteristics of the well at the time of its withdrawal from overhaul are:
with a mouth mouth diameter of 0.012 m, a gas flow rate of 160 thousand nm ³ / day without signs of sand and water occurrence. Thus, the anhydrous gas flow rate increased 2.2 times, which indicates the successful restoration of the bottom-hole zone of the gas well formation.

EXAMPLE 4. The method is implemented during the overhaul of the well 660 of the North Stavropol UGS embedded in the deposits of Hadum. Geological and technical characteristics of the well:
The interval of occurrence of Hadum deposits, m - 690-730
Depth of descent of the production casing, m - 789.5
Diameter of production casing, m - 0.168
The thickness of the wall of the production casing, m - 0,009
Production casing perforation interval, m - 695-725
Type of perforation - bullet
Perforation density, holes / linear meters - 15
The installation interval of the sand bridge in the production casing, m - 740-779.5
Depth of descent of the tubing string, m - 665
The diameter of the tubing string, m - 0,073
The wall thickness of the tubing string, m - 0,0055
The area of the tubing tubing, m ² - 0.00302
The area of annular space of tubing, m ² - 0,01351
Maximum permissible bottomhole pressure in the well, MPa - 8.4
Type of Christmas tree fittings - AFC 3-65 x 210 according to GOST 13846-89
Connection of a well with a gas distribution point - through an individual gas pipeline
After 7 cycles of gas injection-sampling, signs of destruction of the bottom-hole zone of the formation began to appear:
in the sump of the well, a sand-clay plug formed from a depth of 730 m;
gas flow rate dropped from 95 thousand n.m ³ / day to 34 thousand n.m ³ / day with a depression of 0.5 MPa on the formation;
when trying to intensify the flow of gas by powder treatment of the formation due to the formation of a downhole cavity, the production string was broken at a depth of 699 m.

 To carry out the overhaul of the well, an A-50M lifting unit is mounted on it.

 Gas is taken from the tubing string with a gradual increase in depression on the formation due to an increase in the diameter of the wellhead fittings before the start of the formation water removal. An increase in the depression on the formation is judged by a decrease in the wellhead pressure of the gas in the annular space of the tubing, which is measured by the MP-4U pressure gauge with a measurement limit of 16 MPa installed on the fountain. Gas and water flow rates are measured at a gas distribution point.

With a wellhead nozzle diameter of 0.007 m, the wellhead pressure of the gas in the annulus of the tubing is 2.6 MPa and dry gas is taken from the well with a flow rate of 23 thousand n.m ³ / day.

With a wellhead nozzle diameter of 0.009 m, the wellhead pressure of the gas in the annulus of the tubing is 2.5 MPa, and dry gas is taken from the well with a flow rate of 36 thousand n.m ³ / day.

With a wellhead nozzle diameter of 0.011 m, the wellhead pressure of the gas in the annulus of the tubing is 2 MPa, and formation water begins to flow from the well with increasing flow rate from 0.5 m ³ / day with a gas flow rate of 44 thousand m ³ / day.

 Gas withdrawal is stopped and gas is pumped into the reservoir through the tubing string until a steady state filtration is achieved. Gas is supplied from a gas distribution point. The mode of gas filtration in the formation is judged by the wellhead pressure of the gas in the tubing string, which is measured by an MP-4U pressure gauge with a measuring range of 16 MPa installed on the fountain valves, and the gas flow rate, which is measured at the gas distribution point.

The initial pressure of gas injection is 3 MPa at the mouth of the tubing string at a gas flow rate of 50 thousand nm ³ / day. Further, the gas injection pressure is 3.2 MPa at the mouth of the tubing string at a gas flow rate of 50 thousand n.m ³ / day.

 At the last indicated characteristics, gas injection stabilizes, which indicates the achievement of a steady state filtration.

 Stop the well to measure steady wellhead gas pressure in the tubing string and tubing annulus. The indicated pressures stabilized at 2.7 MPa.

 Rebind the fountain reinforcement according to the scheme described in example 1.

 To restore the bottom-hole zone of a gas well formation, NTR is used, which forms both a gas-permeable and waterproof stone after curing. The formulation and characteristics of the cement slurry and stone are similar to those specified in example 1.

For pushing STR, killing the well and washing out excess STR from the tubing string and annular space using industrial water with a density of 1000 kg / m ³ .

Исходя из суммарного вынесенного объема продуктов разрушения коллектора, принимают и приготавливают НТР в объеме V_НТР=3,5 м³.The maximum technologically permissible volume of NTR V V _{NTR max} is determined from the conditions for the development of the maximum allowable bottomhole pressure when leaching the entire volume of NTR in the annular space of the tubing

Based on the total delivered volume of the destruction products of the collector, NTR is taken and prepared in the volume of V _NTR = 3.5 m ³ .

Prepare NTR in a container with a volume of 4 m ³ according to a technology similar to that specified in example 1.

For the preparation of 3.5 m ^{3 of} NTR, 1 m ^{3 of} process water, 59 kg of soda ash, 0.4 m ^{3 of a} 4% aqueous solution of polyvinyl alcohol PVA 18/11, 1.2 m ^{3 of} diesel fuel, 2000 kg of grouting Portland cement PCT II are used -100, 109 kg of wood sawdust with a dispersion of not more than 2 mm.

 At the same time, the measuring tanks of all cementing units connected with fountain fittings are filled with technical water.

At the end of the preparation of the NTR, it is pumped into the tubing string with a pump flow rate of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump sleeve diameter of 0.115 m. installed on the fountain. Figure 4 presents graphs of changes in the current values of the wellhead pressure of the gas in the annular space of the tubing and its maximum allowable value when pumping and forcing the STR through the tubing string. The designations are the same in figure 1 with the exception of point C.

After injection of the 1st m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 2.7 MPa.

текущее устьевое давление газа в заколонном пространстве НКТ составляет 2,8 МПа. Начало повышения этого давления свидетельствует о практически полном заполнении каверны и скважины до верхних перфорационных отверстий. Сравнивают значение последнего с его максимально допустимой величиной, предварительно определенной по формуле

Так как текущее устьевое давление газа в заколонном пространстве НКТ не достигает его максимально допустимой величины, закачивание НТР продолжают. После закачивания 3-го м³ НТР текущее устьевое давление газа в заколонном пространстве НКТ 2,9 МПа, которое не достигает его максимально допустимой величины, предварительно определенной по формуле

ввиду чего закачивание НТР продолжают. После закачивания 3,5 м³ НТР (всего приготовленного объема) текущее устьевое давление газа в заколонном пространстве НКТ 3 МПа, которое не достигает его максимальной допустимой величины

затем осуществляют продавливание НТР по колонне НКТ технической водой в объеме
V_пж=(665-100)•0,00302=1,7 м³.After pumping a portion of NTR in the volume

The current wellhead gas pressure in the annular space of the tubing is 2.8 MPa. The beginning of the increase in this pressure indicates the almost complete filling of the cavity and the well to the upper perforations. The value of the latter is compared with its maximum allowable value, previously determined by the formula

Since the current wellhead pressure of the gas in the annular space of the tubing does not reach its maximum permissible value, pumping of the scientific and technological revolution continues. After the injection of the 3rd m ³ NTR, the current wellhead gas pressure in the annular space of the tubing is 2.9 MPa, which does not reach its maximum allowable value, previously determined by the formula

in view of which the pumping of NTR continues. After injecting 3.5 m ^{3 of} NTR (total volume prepared), the current wellhead gas pressure in the annular space of the tubing is 3 MPa, which does not reach its maximum allowable value

then carry out the pushing of the STR along the tubing string with technical water in the amount
V _pzh = (665-100) • 0.00302 = 1.7 m ³ .

The pushing of the NTR is carried out with a pump feed of 0.0041 m ³ / s, corresponding to the operation of the cementing unit CA-320M in second gear with a pump bush diameter of 0.115 m.

ввиду чего закачивание продавочной жидкости продолжают.After the injection of 1 m ^{3 of} squeezing liquid, the current wellhead gas pressure in the annulus of the tubing is 3.3 MPa, which does not reach its maximum allowable value, previously determined by the formula

whereby pumping of the squeezing liquid continues.

закачивают техническую воду в заколонное пространство НКТ с одновременным контролем устьевого давления в колонне НКТ.After pumping 1.7 m ^{3 of} squeezing fluid, the current wellhead gas pressure in the annular space of the tubing is 3.6 MPa, which does not reach its maximum allowable value, previously determined by the formula

process water is pumped into the annular space of the tubing with simultaneous monitoring of wellhead pressure in the tubing string.

After pumping 2 m ^{3 of} technical water into the annular space of the tubing, the current value of the wellhead pressure in the tubing string increases to the calculated value
P _{at tubing} = 8.4 • 10 ⁶ -1000 • 9.81 • (665-100) -1360 • 9.81 • 100 = 1.5 MPa,
which corresponds to the achievement of the maximum allowable bottomhole pressure.

 Stop pumping industrial water into the annular space of the tubing.

Well killing is performed with the simultaneous leaching of excess NTR from the tubing string and tubing annulus by resuming pumping of technical water into the tubing string with a pump feed of 0.0041 m ³ / s and controlled bleeding of the gas-liquid mixture from the tubing annulus.

To wash excess STR from the tubing string, industrial water is pumped into it in a volume
V _pzh1 = 100 • 0.00302 = 0.3 m ³ .

At the same time, the wellhead pressure in the tubing string is increased to the value of the maximum allowable wellhead pressure in the tubing string at the time of the complete washing out of the STR from the tubing string, determined by the formula
P _{at tubing1} = 8.4 • 10 ⁶ -1000 • 9.81 • 665 = 1.9 MPa.

Для вымывания излишков НТР из заколонного пространства НКТ в колонну НКТ закачивают техническую воду в объеме
V_пж2=665•0,01351=9 м³.The wellhead pressure growth rate in the tubing string is set by the degree of opening of the adjustable choke DR-50 x 21 K2 and maintained at

To wash excess NTR from the annular space of the tubing, technical water is pumped into the tubing string in a volume
V _pzh2 = 665 • 0.01351 = 9 m ³ .

At the same time, the achieved wellhead pressure in the tubing string is kept constant and equal to P _{at tubing1} = 1.9 MPa by changing the degree of opening of the adjustable choke DR-50 x 21 K2.

 Dismantle the fountain fittings, connect the tubing string to the cementing unit ЦА-320М for washing the cup and washing the sump, as in example 1.

When the pump feeds 0.0079 m ³ / s, corresponding to the operation of the cementing unit CA-320M in third gear with a pump bush diameter of 0.115 m, direct circulation of process water is restored.

 By lowering the tubing string with washing to a depth of 725 m of the lower boundary of the perforation interval, the cup is washed out of the STR and then the sump is washed in the range of 725-740 m.

 The tubing string is raised to a depth of 665 m — beyond the upper boundary of the perforation interval.

 Mount fountain fittings at the mouth.

 The well is left for a period of waiting for the curing of the cement slurry - 72 hours.

A fountain reinforcement is tied up for well development, as in Example 1. In a measuring unit of a cementing unit, a foaming liquid is prepared by mixing 4 m ^{3 of} industrial water and 0.02 m ^{3 of a} 40% sulfonol solution (TU 6-01-1043-75). At the same time, a foaming liquid is injected into the annular space of the tubing with a flow of 0.0041 m ³ / s and compressed air with a flow rate of 9 m ³ / min. The beginning of the removal of foam from the well is obtained at wellhead pressure in the annular space of the tubing of 3.7 MPa. After the removal of foam and process water is stopped, the well is stopped and the fountain fittings are connected with a gas pipeline from the gas distribution point to take gas through the tubing string.

The operational characteristics of the well at the time of its withdrawal from overhaul are at a wellhead nozzle diameter of 0.015 m - gas flow rate of 60 thousand n.m ³ / day. without signs of sand and water. Thus, the anhydrous gas flow rate increased by 2 times, which indicates the successful restoration of the bottom-hole zone of the gas well formation.

 The total cost of time when implementing the method compared with the known decrease by 47%.

Claims (2)

1. A method of restoring the bottom-hole zone of a gas well formation, including preparing a grouting mortar that forms a gas-permeable stone after curing, pumping and forcing it through a tubing string using a squeezing fluid through the perforation holes of the production string, killing the well, washing out excess grouting mortar from tubing string and tubing annulus, removal of the beaker from the production string to the lower boundary of the perforation interval, sump cleaning, burning Contents curing grouting mortar, well completion, characterized in that the prepared plugging nefteemulsionny solution (STD), comprising water and a hydrocarbon liquid in a ratio by weight. hours, equal to 1: 0.63 - 0.83, and a mass ratio of liquid and solid phase of 1.04 - 1.26, forming both a gas-permeable and waterproof stone after curing, additionally take gas through the tubing string with a gradual increase in depression to the reservoir before the start of the removal of produced water, pump gas into the reservoir through the tubing string until a steady state of filtration is achieved, stop the well, measure the steady wellhead pressure of the gas in the tubing string and the annular space of the tubing, continuously monitor the current wellhead pressure gas in the annular space of the tubing in the process of pumping and forcing the STR through the tubing string, compare the value of the latter from the moment of pumping a portion of STR, the volume of which is calculated by the formula

where V _{p NTR} - the volume of a portion of NTR, m ³ ;
P _{zab add} - the maximum allowable bottomhole pressure in the well, Pa;
S _tubing - the area of the tubing tubing, m ² ;
ρ _NTR - density of NTR, kg / m ³ ;
q - acceleration of gravity, m / s ² ,
or the volume of all prepared NTR and a portion of the squeezing liquid, the volume of which is calculated by the formula

where V _{p pzh} - the portion size of the squeezing fluid, m ³ ;
V _NTR - the volume of all prepared NTR, m ³ ;
ρ _pzh - the density of the displacement fluid, kg / m ³ ,
with its maximum allowable value, previously determined by the formula

where P _{at sn} - the maximum allowable wellhead pressure in the annular space of the tubing, Pa;
S _sn - the area of the annular space of the tubing, m ² ;
V _NTR - the current volume of injected NTR, m ³ ;
V _pzh - the current volume of pumped squeezing fluid, m ³ ,
moreover, upon reaching the current value of the wellhead pressure of the gas in the annular space of the tubing, its maximum permissible value is released from the annular space of the tubing with a rate calculated by the formula

where ΔP _{at sn} (t) is the rate of gas release from the annular space of the tubing, Pa / s;
Q - pump flow, m ³ / s,
until the end of pumping and forcing of the STR, when the current value of the wellhead pressure of the gas in the annular space of the tubing is not reached its maximum permissible value after the end of the pushing of the STR, technical water is pumped into the annulus of the tubing with simultaneous monitoring of the wellhead pressure in the tubing string until the current value of the wellhead pressure in the string is reached Tubing value determined by the formula

where P _{at the tubing} is the maximum allowable wellhead pressure in the tubing string when pumping squeezing fluid into the annular space of the tubing, Pa;
L _tubing - the depth of the tubing, m;
h _NTR - the height of the column of NTR left in the tubing string at the end of the pushing of the NTR, m,
and killing a well is carried out after pushing the STR along with washing out the excess STR from the tubing string and the annulus of the tubing by pumping the squeezing fluid into the tubing string while simultaneously regulating the pressure in the tubing string by bleeding the gas-liquid mixture from the annulus of the tubing with an increase in wellhead pressure in the tubing string, determined by the formula

where ΔP _{at HKT} (t) is the growth rate of wellhead pressure in the tubing string, Pa / s,
to the value of the maximum allowable wellhead pressure in the tubing string at the time of complete washing out of the STR from the tubing string, determined by the formula
P _{at HKT1} = P _{zab extra} - ρ _pzh • q • L _HKT ,
where P _{at tubing1} is the maximum allowable wellhead pressure in the tubing string at the time of complete leaching of the STR from the tubing string, Pa,
and the washing out of the excess NTR from the annular space of the tubing is carried out at a constant maximum achievable wellhead pressure in the tubing string, then the glass is removed from the production string to the lower boundary of the perforation interval by washing and the sump is cleaned. 2. The method according to p. 1, characterized in that the predominantly prepared oil emulsion cement slurry of the following composition, wt. hours:
Grouting Portland cement - 100
Sawdust - 5-8
Soda Ash - 3 - 10
Polyvinyl alcohol - 0.8 - 0.9
Diesel - 44 - 56
Water - 59 - 82

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