SU1530764A1 - Method of isolating interacting strata - Google Patents

Abstract

The invention relates to the drilling of oil and gas wells, simultaneously exposing several absorbing and water-bearing formations with different formation pressures. The goal is to increase the efficiency of joint isolation of interacting layers due to more complete plugging of permeable channels with latex coagulation products. Isolation is carried out by sequential injection into the well of fresh water and latex coagulating upon contact with saline water, pushing them into permeable formations with saline water containing not less than 1.7 g / l in the amount of not less than a trunk. wells from the top to the bottom of the bottom of the reservoir, followed by periodic fluid withdrawal from the reservoir and pumping it into the reservoir, performed after a time determined by the formula T = (1 / 5-1 / 2) VC / QN, where VC is the injected volume latex, QN - amount arna cross-flow efficiency, with an increase in the volume of reservoir fluid in cycles, with fresh water being pumped in an amount of from 0.7 to 1.2 volumes of latex, and the flow rate of fresh water, latex and reservoir fluid during injection into the well is chosen in such a way as to ensure simultaneous flow of the injected fluid into the interacting formations. The method allows the elimination of absorption and water supply of interacting layers with different gradients of reservoir pressures with minimal amounts of additional insulation work.

Description

The invention relates to the drilling of oil and gas wells and can be used in the drilling of exploration, hydrogeological and other wells, which simultaneously: open two or more absorbing and

reservoirs with different formation pressures.

The purpose of the invention is to increase the efficiency of joint isolation of interacting formations by more fully plugging permeable channels with latex coagulation products.

Isolation is carried out by sequential injection into the well of fresh water and latex coagulating upon contact with saline water, pressing them into permeable formations with saline water containing salts of two- and trivalent metals in an amount of not less than 1.7 g / l, the volume of not less than the volume of the well bore from the top to the bottom of the bottom of the reservoir, followed by periodic extraction of the formation fluid and pumping it into pastes, performed through time determined by the formula

.Vr

t (1 / 5-1 / 2) p. Pe

(one)

where Vc is the injected volume of latex;

QP is the total intensity of the interlayer flow, with an increase in the volume of reservoir fluid in cycles, with fresh water being pumped in an amount of from 0.7 to 1.2 volumes of latex, and the flow rate of fresh water, latex and reservoir fluid during injection into the well is determined by the formula

,. (- f). (b-Z) +

 t E PR. .)

fluid flow in the reservoir i

per unit time, calculated for all interacting formations;

the coefficient depending on the shape and size of the channels in the reservoir under number i;

for cavernous and granular rocks;

for fractured rocks;

respectively, the average equivalent diameter of the channels and

crack opening; effective viscosity of injected cement mixture;

0

five

0

m

, 0 h

g z; LR - actual wellbore radius in the interval of the 1st stratum;

-thickness of the i-ro formation, counted from above;

- the porosity of the i-ro layer is effective;

density of injected fluid; density of natural produced water;

the distance from the top roof to the bottom of the bottom layer; acceleration of the power of the tin; the distance from the roof of the i-ro reservoir to the roof of the upper reservoir;

maximum pressure drop between interacting formations.

five

0

five

0

45

0

five

Preliminary injection of buffer fresh water allows to displace mineralized water from the bottomhole formation zone and prevent premature coagulation of large amounts of latex. However, part of it remains in the recesses of the local broadening of the channels, between the projections of the rough walls, in the form of a film on the walls of the channels, and also due to the gravitational separation of liquids due to the difference in density. This amount of saline water is sufficient to coagulate part of the latex and, therefore, before-; vamping plugging of a part of the channels.

The complete displacement of a latex solution by a squeezing fluid using special injection modes prevents its salinity during the displacement of saline water flowing between the layers, and the parameters of the injection mode of fresh water and latex from the moment fresh water approaches the top of the upper layer are calculated by calculation. differential pressure between the interacting formations, taking into account the density difference between the injected water and the fluid filling the well,

according to the formula (2). This ensures the simultaneous flow of the injected fluid into the interacting formations and the circulation of mineralized minerals into them.

water, which contributes to the complete coagulation of the latex and, accordingly,

 increased clogging effect.

ten

5153076 6

As the first portion of the sludge fluid, mineralized fluid is injected (formation water, aqueous solutions of salts, saline mud, including those treated with filler, etc.). The volume of the portion is equal to the volume of the wellbore in the interval from the top of the top to the bottom of the bottom layer. This portion, participating in the flow of fluid between the layers and thereby entering the channels of the reservoir, contributes to the acceleration and completeness of latex coagulation.

Keeping the process pause) 5 of the cementing unit after the latex has been completely pushed into the formations allows the use of menstrual overflows of saline water to further coagulate the latex found in the formations. The duration of the pause is selected depending on the intensity of the water flow between the layers by the formula (1).

Periodic selections and downloads

153076

In the case of their bedding, unplowed water is placed. It is held technologically for 30 minutes, with the goal to provide between layers, causing latex with mineralization and its transformation into coagula of layers.

In order to effect the latex reaction with the mineral water within the formations, the reject is pumped back into the water. Injection pressure by

injections increase from 7.5 MPa with a gata manufacturer of 30 m3 / h; residual g 6 MPa, which for up to 3 MPa.

Repeatedly sampled and from the second well into the well, 6 m. By the end of the extraction, the inflow decreases

20

ten

 5 cementing unit

076

A portion of water depletion water is located at their disposal. Thereafter, a technological pause is maintained for 30 minutes in order to ensure the flow between the layers, causing the latex to mix with saline water and turn it into a coagulum in the channels of the layers.

To accomplish a more complete reaction of the latex with the saline water inside the formations, 3 m of water is withdrawn and injected back into the well. Pressure gauge loading

by the end

injections increase from 4.0 to 7.5 MPa with an aggregate capacity of 30 m3 / h; residual pressure of 6 MPa, which is within 5 min. up to 3 MPa.

A second portion of water with a volume of 6 m is re-sampled and injected into the well. By the end of the extraction, the inflow intensity is practically reduced.

back into the seams of fluid, the production is 25 ki to 0. When re-injecting the davles at the rate of sequentially increasing the withdrawn and injected volumes of the fluid 1.5-2 times compared to the previous one, bring them up to 0.5 volume of the cement slurry in the third selection operation - download. This ensures effective mixing of latex with saline water in the channels of the layers and its most complete use.

Example. Two water-bearing formations are opened in the intervals of 102-1026 m and 1069-1071 m with injectivity coefficients of 33 and 110 m3 / h MPa, a pressure difference between the layers of 0, MPa, an interstrate flow intensity of 13. m3 / h, a static wellhead the pressure after the opening of the upper layer is 1.2 MPa, the lower 0.8 NPa.

To carry out the isolation works, a packer is installed at a depth of 925 m. 15.3 m of fresh water is injected in succession, m3 of the SCS-50 KGP latex shut up in 8 m of fresh water, 2 m3 of fresh water as a buffer, 6 m3 of mineralized water with a density of 1, 12 g / cm 3 and 7.5 m 3 of fresh water. The initial injection pressure of latex into the formation is 2.5 MPa, final, 0 MPa.

At this stage of work, latex is forced out, into permeable formations and in the interval

The ratio increases from 5 to 8 MPa with the same capacity of the unit.

Thus, the coefficient of injectivity is reduced below the value required for the transition from washing with water to washing with clay mud.

The third time is the extraction of 5 m3 of water from the well and pumped through the packer

18

mud solution

with a density of 1.2 g / cm3 with the addition of sawdust in the first batch (TO m3) of the solution. After injection of 1b m3 solution, i.e. when, by calculation, the wellbore is filled in the complication interval, the injection pressure increases to 9 MPa. Upon reaching a pressure of 9.5 MPa (residual pressure of 8 MPa), further injection stops and a normal transition to the mud is made.

At the final injection pressure after the third operation, a take-back injection of less than 5-6 flfla transition to flushing the mud-based mud is carried out after pumping a portion of the mud with fillers or cement mortar with fillers and set accelerator.

Thus, the prelimi- nary method allows the elimination of the absorption and water flow of interacting formations with different gradients.

tami reservoir pressure at minimum

volume of additional insul

ny works.

Claims (1)

Invention Formula The method of isolating interacting formations, including pumping latex coagulating npkT contact with saline water into the well and pushing it into permeable plates with subsequent periodic withdrawal of fluid from the formation and injecting it into the formation, characterized in that, in order to increase the effect of jointly isolating the interacting formations due to a more complete plugging of permeable channels, latex coagulation products, before injection of latex into the reservoir, 0.7-1 is additionally pumped in fresh water, - volume malatex, and latex is forced into permeable formations with saline water containing salts of two and trivalent metals in an amount of not less than 1.7 g / l, in an amount not less than the volume of the wellbore from the top to the bottom of the bottom formation, while periodically sampling and pumping formation fluid is produced in time determined by the following formula: .1, / 0 Vc five- where Vj is the injected volume of latex; Р „- total intensity of inter- reservoir flow; moreover, the consumption of fresh water, latex and formation fluid during injection eight determined by. form " + LP, where Q; 0 five n Q , yyChih; rn; g (p-p,) (h-ZlU 0 five , 6x chkg a , 2 "where d; and S: fluid flow in the formation i per unit of time, calculated for all interacting formations; Cj is the coefficient depending on the shape and size of the channels in the reservoir; for cavernous and granular rocks; - for fissure rocks; five 0 s. I h: respectively, the average equivalent diameter of the channels and the opening of cracks; effective viscosity of injected fluid; the actual well radius in the interval of the i-ro formation; thickness; t - effective porosity; g is the acceleration of the force of gravity; the density of the injected fluid: the density of the natural produced water; the distance from the top roof to the bottom of the bottom layer;  ; - distance from the roof of the i-ro reservoir to the roof of the upper reservoir; p is the maximum pressure drop between the interacting formations. R RP h