RU2165514C1 - Process of opening of productive inclined seam with pressure mode of production of hydrocarbons - Google Patents

Abstract

FIELD: drilling of inclined and horizontal holes. SUBSTANCE: zenith angle of shaft is set on roof of productive seam up to 90 degrees in process of drilling, then horizontal sections of shafts of single-face or multiface holes are drilled with inclination angle of 0 degree. As result of analysis of structural map in case of single-face hole horizontal section is drilled in direction perpendicular to outer or inner outline of gas-and-oil or water-and- oil contacts. Length of section is found by calculation. In case of multiface hole length of horizontal section of shaft is also found by calculation and hole is drilled at certain angle formed in plan of seam by axis of each horizontal section with outer or inner outline of gas-and-oil or water-and-oil contacts. EFFECT: improved technological indices in development of deposit, avoidance of expenses related to drilling and running of commercial and estimation holes. 4 dwg

Description

 The invention relates to the oil industry, in particular to drilling wells, and can be used when opening reservoirs.

Analysis of the current level of technology showed the following:
In the practice of drilling wells, methods are known for opening a reservoir with horizontal wells that differ in shape and profile size of a horizontal section, depending on the structure, angle of inclination of the reservoir and the conditions of occurrence of hydrocarbons. Moreover, the length and shape of the horizontal section is finally chosen only after drilling and trial operation at a specific field of several industrial-appraisal horizontal wells.

 There is a method of opening a productive inclined bed by drilling a horizontal wellbore parallel to its roof (see A.G. Kalinin, B.A. Nikitin, K.M. Solodky, B.Z. Sultanov. Handbook. Drilling of deviated and horizontal wells. Moscow, Nedra, 1997, pp. 133-137).

 The disadvantage of this method is that the known orientation in the space of the profile of the well does not allow to achieve high technological indicators of the development of deposits and requires the drilling and operation of industrial evaluation wells. Wells are hydrodynamically imperfect, because the layer is not fully opened in thickness. Large volumes of displacing agent are produced together with hydrocarbons, which significantly lengthens the development period and worsens the operating conditions of the wells, and in the case of oil displacement by water, it requires significant costs for the construction of facilities for the preparation and injection of produced water into absorbing or developing horizons. Drilling and trial operation of several industrial-appraisal horizontal wells are caused by uncertainty in the choice of the drilling direction, length, shape and angle of the projected horizontal section of the wellbore in the reservoir.

 As a prototype, a method for opening a productive oblique bed with a pressure mode of hydrocarbon production by drilling a hollow directional horizontal wellbore from the roof to the bottom (see A.G. Kalinin, B.A. Nikitin, K.M. Solodky, B.Z. Sultanov, Reference book: Drilling of deviated and horizontal wells, Moscow, Nedra, 1997, p. 133, 139). Hollow directional horizontal sections are designed predominantly tangential.

 The disadvantage of this method is that the known orientation in the space of the profile of the well does not allow to achieve high technological indicators of the development of deposits and requires the drilling and operation of industrial appraisal wells. Large volumes of displacing agent are produced together with hydrocarbons, which significantly lengthens the development period and worsens the operating conditions of the wells, and in the case of oil displacement by water, it requires significant costs for the construction of facilities for the preparation and injection of produced water into absorbing or developing horizons. Drilling and trial operation of several industrial-appraisal horizontal wells are caused by uncertainty in the choice of the drilling direction, length, shape and angle of the projected horizontal section of the wellbore in the reservoir.

The technical result that can be obtained by carrying out the claimed invention is as follows:
the proposed orientation in the space of the wellbore profile provides an improvement in the technological indicators of the development of the reservoir and eliminates the cost of drilling and operating industrial appraisal wells.

 Moreover, the period of operation of production wells with a gradually increasing proportion of displacing agent in production is completely eliminated, which eliminates the cost of its disposal and improves the operating conditions of the wells. Eliminates the need for drilling industrial appraisal horizontal wells, because at the design stage, you can determine the orientation in space of the guide and horizontal parts of the well.

где S₁ - длина горизонтального участка однозабойной скважины в продуктивном пласте, м;
h - истинная толщина продуктивного пласта, м;
α_пл - угол наклона продуктивного пласта, град.,
а в случае многозабойной скважины горизонтальные участки ствола бурят под углом, образованным в плане пласта осью каждого горизонтального участка с внешним или внутренним контурами ГНК или ВНК, и определяемым из выражения

где β_м - угол, образованный в плане пласта осью каждого горизонтального участка ствола скважины с внешним или внутренним контурами ГНК или ВНК, град.;
C - расстояние между внешним и внутренним контурами ГНК или ВНК, м;
σ - половина расстояния между добывающими скважинами в ряду, м,
а их длину определяют по формуле

где S₂ - длина каждого горизонтального участка ствола многозабойной скважины, м.The technical result is achieved using the known method of opening a productive directional bed with a pressure mode of hydrocarbon production, including drilling a productive formation from the roof to the bottom with single or multilateral horizontal wells, in which horizontal sections of single and multilateral wells are drilled with an angle of 0 ^o , and when visual analysis of the structural map of the reservoir in the case of a one-hole well, the horizontal section is drilled in the direction perpendicular to the external or internal contours of gas-oil or water-oil contacts (SOC or BOC), and its length is determined by the formula

where S ₁ - the length of the horizontal section of a single-well borehole in the reservoir, m;
h is the true thickness of the reservoir, m;
α _PL - the angle of inclination of the reservoir, deg.,
and in the case of a multilateral well, horizontal sections of the well are drilled at an angle formed in the formation plan by the axis of each horizontal section with the external or internal contours of the SOC or BOC, and determined from the expression

where β _m is the angle formed in the plan of the reservoir by the axis of each horizontal section of the wellbore with the external or internal contours of the SOC or BOC, deg .;
C is the distance between the external and internal circuits of the SOC or BOC, m;
σ - half the distance between production wells in a row, m,
and their length is determined by the formula

where S ₂ - the length of each horizontal section of the trunk of a multilateral well, m

 In FIG. 1 shows a productive formation, opened by horizontal sections of the wellbore, located: 1 - parallel to the roof of the formation; 2 - gently directed, with 3 - the line of KSS, 4 - the line of GNK.

 During the filtration of agents of different densities in a porous medium, their gravitational separation occurs, and the contact line of the separated agents occupies a horizontal position along the section of the formation, regardless of the angle of inclination.

 In the process of artificial or natural flooding of a reservoir, oil is displaced by water in order to increase development efficiency in the direction from bottom to top. When the VNK line reaches the lower holes of the well filter, the anhydrous period of operation passes into the water one. Further advancement of the VNK line is accompanied by a gradual increase in the amount of water in the produced product until it is completely irrigated. The increase in the length of the horizontal section of the trunk in the reservoir with known methods of opening the hole will lead to a reduction in the period of waterless operation and an increase in the water period.

 During the water period of operation of the well, several tens of tons of water are produced per ton of oil, which increases operating costs and lengthens the term of development of the reservoir. In addition, to prevent damage to the environment, material costs are required for the construction of facilities for the preparation of produced water and its injection into absorbing or developing formations.

 The presence of water in the produced products worsens the operating conditions of the wells and leads to a number of negative consequences.

 Under conditions, for example, of the Vorobyevskoye field (Stavropol Territory), combined filtration of water and oil in a porous medium leads to the formation of a persistent water-oil emulsion with anomalously high viscosity in the bottom-hole zones, which blocks the flow of oil from the reservoir into the wells and causes them to stop. Resumption of oil production is possible only after the destruction of the emulsion in the bottomhole zone during the overhaul of wells.

 The increase in water content in produced products is accompanied by an increase in its density in the wellbore and a convergence in terms of reservoir and bottomhole pressures. The decrease in the difference between the reservoir and bottomhole pressures leads to a decrease in oil flow rate, rise rate and production temperature in the wellbore, which creates the conditions for the precipitation of salts, paraffin, resins on the walls of downhole equipment, surface equipment. Under these conditions, taking into account the presence of water in the produced products, the corrosion rate of the equipment increases and there may be complications during the operation of the wells.

 Due to the increase in the density of production, in connection with an increase in the content of water in it, the reservoir energy becomes insufficient to provide a fountain production method. Therefore, the wells are transferred to a more expensive mechanized method.

 In the process of developing a deposit by injecting gas, oil is displaced by it in order to increase oil recovery in a downward direction. When the GOC line reaches the upper holes of the horizontal well filter, the gas factor increases. Further advancement of the GOC line with well-known methods of opening is accompanied by a sharp increase in the gas factor of the produced products until the wells completely shut off. The efficiency and duration of the well will not depend on the length of the horizontal section of its wellbore in the reservoir, because gas, having reached the upper holes of the filter of a horizontal well, after some time will block the flow of oil from the porous medium through the lower part of the holes of the filter.

 For the disposal of gas from a well with liquid hydrocarbons, material costs are required. Burning gas or releasing it into the atmosphere is harmful to the environment.

 In addition, the selection of gas from the reservoir leads to unproductive loss of reservoir energy. Therefore, wells with high gas factors are stopped and in this regard, the oil production per each well is reduced.

 Oil from the filter of a stopped well is pushed by gas to the next well in the reservoir, which often leads to oil losses due to heterogeneity of the porous medium.

In FIG. 2 shows the profile of the designed well with a horizontal section of the wellbore in the reservoir, where H _in is the length of the vertical section of the wellbore; H _g - vertical projection of the depth of the well at the end of the horizontal section; α is the zenith angle; R is the radius of curvature of the plot to increase the zenith angle of the well; α _PL - the angle of inclination of the reservoir; h is the true thickness of the reservoir; A _g - horizontal projection of the displacement of the well at the end of the horizontal section; A is the projection of the displacement of the profile at the design depth; S ₁ or S ₂ is a horizontal projection of a portion of a single-well or multi-well wellbore in a reservoir; 1 - a vertical section of the wellbore; 2 - plot increase zenith angle; 3 - horizontal straight section of the wellbore; 4 - line VNK; 5 - line GNA; 6 - the point of intersection of the line of the SOC or KSS with the roof of the formation (symbol of the external contour of the GKK or KSS, respectively); 7 - the point of intersection of the line of the SOC or KSS with the bottom of the formation (symbol for the internal contour of the GSC or KSS, respectively).

According to the claimed technical solution, the zenith angle on the top of the formation should be strictly 90 ^o . This is due to the need to continue drilling a horizontal section of the wellbore within the reservoir with an inclination angle of 0 ^o . Moreover, a set of zenith angle up to 90 ^o does not mean that further drilling will be carried out as described in the claimed technical solution, since subsequent drilling options are possible with any deviation of the borehole section in the reservoir from the horizontal. Next, we chose the drilling operation with an angle of inclination of the horizontal section of the wellbore 0 ^o . Since the angle of inclination during drilling is the deviation of the axis of the wellbore from the horizontal, the drilled horizontal section of the wellbore with an angle of inclination of 0 ^° is located in the section of the formation parallel to the lines of the OWC or GOC. The advance of the BHK lines from the bottom up or the BHC from top to bottom will be accompanied by full coverage of the thickness of the formation. A breakthrough of gas or water will occur simultaneously along the entire length of the well filter within the thickness of the reservoir. At the moment of gas or water breakthrough into the well, all oil contained in the reservoir above or below the horizontal section of the well will be recovered. Therefore, during the development of the reservoir, the period of water production or joint production of gas and oil is excluded, which means that the operating conditions of the wells are improved.

In FIG. Figure 3 shows the structural map of a reservoir with single-hole horizontal wells, where 1, 2 are the wellhead and bottomhole, respectively; 3, 4 are the external and internal contours of the oil-well contact system, respectively; β ₀ is the angle formed in the plan of the reservoir by the axis of the horizontal section of the wellbore and the external or internal contours of the OWC.

 The reservoir can be opened with single or multilateral wells.

 It is advisable to open small deposits in order to ensure a positive economic effect with single-hole wells with the smallest possible length of the horizontal section of the well in the reservoir. Reducing the length of the horizontal section of the wellbore in the reservoir can significantly reduce the cost of drilling a well. For example, in the conditions of the Coastal field (Krasnodar Territory), 4 thousand rubles are spent on 1 meter of penetration. at prices of 1998

 An oblique overburden with a pressure regime of filtration is characterized by the presence of external (along the roof) and internal (along the sole) contours of the SOC or BOC. The distance from the external to the internal contour of the SOC or BOC is the smallest from the roof to the sole for a given orientation of the horizontal section of the wellbore in the reservoir. Therefore, to ensure minimum drilling costs, it is necessary that the axis of the horizontal section of the wellbore in terms of the reservoir be perpendicular to the external or internal contours of the SOC or BOC.

 The length of the horizontal section of the wellbore in the reservoir must be no less and no more than the calculated one.

 If its length is greater than the calculated one, then the horizontal section of the wellbore will go beyond the boundaries of the reservoir. This is technologically impractical and will lead to an unjustified increase in drilling costs.

 If its length is less than the calculated, then the opening of the reservoir by the horizontal section of the trunk will be incomplete, i.e. the well will be hydrodynamically imperfect in the degree of opening. This will lead to incomplete drainage of the thickness of the reservoir and a decrease in the oil recovery ratio.

 In addition, in order to increase the coverage of the productive formation by displacement over the area, the faces of each subsequent row of horizontal wells are shifted by half the distance between them, i.e. wells are located on the area of the deposit according to the chess system. It is known that the efficiency of oil displacement from deposits with staggered wells is 5 - 25% higher compared to their frontal location (see Ch. R. Smith Technology of secondary methods of oil production. Moscow. "Nedra", 1971 - S. 49- fifty).

In FIG. 4 is a structural map of a reservoir with multilateral horizontal wells, where 1, 2 are the wellhead and bottomhole, respectively; 3, 4 - external and internal contours of the VNK, respectively; β _m - the angle formed in the plan of the reservoir by the axis of each horizontal section of the wellbore with the external or internal contours of the oil hole; C is the distance between the external and internal circuits of the KSS; 2 σ is the distance between the producing wells in a row.

 In large fields with reserves of several hundred million tons of oil, an increase in the coefficient of coverage of the reservoir by displacement by even a few percent contributes to additional oil production of several tens of millions of tons.

 To ensure maximum coverage of the hydrocarbon-saturated volume of the reservoir by displacement, it is necessary to completely drain the reservoir in thickness and area.

The most complete drainage over the thickness of the reservoir is carried out by multidirectional production wells with a slope angle of horizontal sections 0 ^o that are hydrodynamically perfect in terms of opening, and the most complete drainage over the area is carried out by creating a continuous sampling line along the width of the reservoir. To do this, the wells are drilled so that the axes of the horizontal sections of the bore make up the calculated angle with the external and internal contours of the SOC or BOC.

If the angle β _m is greater than the calculated one, then the continuous sampling line will break, which will lead to incomplete coverage of the reservoir area by displacement and, as a whole, to a decrease in the coefficient of oil recovery from the reservoir.

If the angle β _m is less than the calculated one, then drilling of longer horizontal sections of the wellbore will be required to open the reservoir from the roof to the bottom. Consequently, drilling costs will unreasonably increase.

 At the same time, the length of each horizontal section of a multilateral well should be no more and no less than the calculated one.

 If the length is greater than the calculated one, the wellbore will go beyond the boundaries of the productive formation, which is impractical in technological and economic respects.

 If the length is less than the calculated, then the thickness of the reservoir will not be opened completely. This will lead to hydrodynamic imperfection of the well, i.e. only part of the formation thickness will be covered by drainage. Consequently, the coefficient of coverage of the thickness of the reservoir will decrease and overall the coefficient of oil recovery from the reservoir will decrease.

 The authors propose the optimal profile of the wellbore at the design stage for opening a productive inclined bed with a pressure mode of hydrocarbon production, which was previously not known from known sources of patent and scientific literature. In any other sources, it is proposed to identify the optimal profile of the wellbore, in particular its horizontal section, according to the results of the analysis of the production data of industrial appraisal wells, which is associated with the cost of their construction and operation. But even in this case, the best selected wellbore profile from the number of drilled wells will not provide maximum technical and economic indicators for the development of the reservoir. Thus, according to available sources of fame, no methods have been identified for opening a productive inclined bed with a pressure mode of hydrocarbon production that match the distinguishing features of the present invention. The claimed technical solution has an inventive step.

In more detail, the essence of the claimed invention is described by the following examples:
Example N 1
Characterization of a hypothetical reservoir exposed by single-hole wells
Depth of bed H _pl , m - 2000
True formation thickness h, m - 10
Formation angle α _pl , degrees - 10
The distance between the external and internal circuits of the KSS C, m - 57.6
The porosity of the reservoir, taking into account the utilization of the pore space m, the share of units - 0.1
The flow rate of one production well q ₁ , m ³ / day - 100
The final water cut of production wells,% - 99
The distance between production wells in a row of 2 δ, m - 500
The density of oil ρ, kg / m ³ - 850
The upper part of the horizontal well should be drilled with a minimum deviation of the barrel from the vertical. The technology of the vertical section of the well is carried out using modern drilling rigs (see A. G. Kalinin, B. A. Nikitin, K. M. Solodky, B. Z. Sultanov. Reference. Drilling of deviated and horizontal wells. Moscow. "Nedra ", 1997, p. 438).

 With artificial deviation of wells from the vertical, downhole hydraulic motors are used, which contain turbine sections as a drive. As a special tool for regulating the direction of drilling, domestic industry produces turbine deflectors and spindle deflectors in series.

 To ensure reliable stabilization of the zenith angle or a given intensity of the borehole curvature, a BHA with support-centering elements is used. The types and types of support-centering elements (calibrators, centralizers, stabilizers) must comply with OST 39-078-79, technical and technological and geological conditions for well drilling (see ibid., Pp. 59, 239, 438). When typing the zenith angle, serial turbine diverters TO - 240 and TO - 195 are used.

 To set the zenith angle along the average radius, diverters based on D-172 downhole screw motors, as well as OSH-172 diverters are used. For continuous monitoring of the process of drilling and drilling horizontal branches using telesystems with a wired communication channel of the type STE, STT, ETO-2, "Course".

где H - проектная глубина направляющей части профиля скважины, м.Calculate the length of the vertical section H _in the formula

where H is the design depth of the guide part of the well profile, m

Вертикальную проекцию глубины однозабойной скважины в конце горизонтального участка H_Г1 рассчитывают по формуле
H_Г1=S₁cos α + H.The radius of curvature R of the plot for increasing the zenith angle of the well is calculated by the formula

The vertical projection of the depth of a borehole at the end of the horizontal section H _{G1 is} calculated by the formula
H _G1 = S ₁ cos α + H.

The radius of curvature of 190 m and the average intensity of curvature in this section, equal to 4.5 ^o per 10 m of penetration, provide an increase in the zenith angle of the wellbore on the roof of the reservoir up to 90 ^o . In the productive part of the reservoir, horizontal sections of the borehole are drilled with a tilt angle of 0 ^o .

 The direction of drilling horizontal sections of shafts of single-hole wells in the reservoir is established as a result of visual analysis of the structural map: the direction of formation fall and the angle of its inclination at the drilling point, the position of the internal and external VNK contours.

Вертикальная проекция глубины в конце горизонтального участка однозабойной скважины будет равна
H_Г1=S₁cos α + H = 57,6·cos90+2000=2000 м.A one-hole well is drilled in the reservoir so that the axis of the horizontal section of the trunk forms an angle β ₀ = 90 ^° with the external and internal contours of the oil hole. The length of the horizontal section of the wellbore in the reservoir is determined by the formula

The vertical projection of depth at the end of the horizontal section of a single-hole well will be equal to
H _Г1 = S ₁ cos α + H = 57.6 cos90 + 2000 = 2000 m.

The horizontal projection of the displacement of the well at the end of the horizontal section A _{G1 is} calculated by the formula
A _g1 = S ₁ · sinβ ₀ + A = 57.6 · sin90 + 190 = 247.6 m.
The drilled horizontal sections of the shafts of single-hole wells are oriented in the section of the productive formation parallel to the contact line of the oil well. And in terms of the formation, the axes of the horizontal sections of the single-hole wells form an angle of 90 ^o with the external and internal contours of the OWC.

За рассчитанное количество суток осуществляется безводная добыча нефти.The characteristic of the technical result:
we take the distance from the well to the initial position of the OWC at the bottom of the formation, L, equal to 209.0 m. Since L is the distance from the well to the initial position of the OWC on the roof, L ¹ the time of water breakthrough into the well along the roof and the bottom of the formation will be the same, t .e. t ¹ = t. Then the time to develop the reservoir

Anhydrous oil production is carried out for the calculated number of days.

The amount of oil produced for the entire period of development of the deposits uncovered by the proposed method is determined by the formula
Q _bezv. t ¹ q = 1371.58 100 = 137 158 t ≈ 137.2 thousand tons

Comparison with prototype:
since the length of the horizontal section of the borehole of a single-well borehole S ₁ in the proposed method for opening the formation is 57.6 m, then the length of the horizontal section of the barrel in the prototype S _{1p is} also taken equal to 57.6 m. The angle formed by the horizontal section of the borehole and the roof of the formation, the calculation is 10 ^o . Then the length of the projection of the horizontal section of the wellbore onto the formation roof is determined by the formula
l ₁ = S _1n · cos10 = 57.6 · 0.9848 = 56.7 m.

To maintain the amount of oil contained between the well and the initial position of the OWC (according to the present method - 137.2 thousand tons), the distance from the well to the initial position of the OWC at the bottom of the formation L _p should be equal to 206.6 m

Время прорыва воды по кровле пласта t_п ¹, т.е. время разработки залежи, определяют по формуле

Скважина до полного обводнения будет работать 3233,472 суток.The distance from the well to the initial position of the OWC on the roof of the reservoir L _p ¹ is determined by the formula
L $\genfrac{}{}{0ex}{}{\text{1}}{\text{P}}$ = L _p + hctgα _pl + l ₁ = 206.6 + 57.6 + 56.7 = 320.9 m.
The time of water breakthrough at the bottom of the formation t _p is determined by the formula

The time of water breakthrough over the top of the formation t _p ¹ , i.e. reservoir development time, determined by the formula

The well until full flooding will run 3,233,472 days.

The operating time of a well with progressive watering is determined by the formula
_ave t = ¹ t _n -t _n = 3233,472-1340,264 = 1893.208 days.

The amount of oil produced during the anhydrous period of well operation for 1340.264 days is determined by the formula
Q _bezv. = t _p q = 1340.264 100 = 134026.4 t.

The amount of fluid produced during the progressive watering of the well for 1893.208 days is determined by the formula
Q _w = t _pr · q = 1893,208 · 100 = 189,320.8 m.

С учетом плотности нефти, на 1 тонну нефти будет добываться 59,4 т воды или 60,4 т жидкости.The average water flow during the progressive watering of wells W is determined by the formula

Given the density of oil, 59.4 tons of water or 60.4 tons of liquid will be produced per 1 ton of oil.

Количество нефти, добытой за все время разработки (3233,472 суток) месторождения, определяют по формуле
Σ Q_н=Q_безв.+Q_н=134026,4+3134,45= 137160,85 т ≈137,2 тыс.т.The amount of oil produced during the progressive watering of the well is determined by the formula

The amount of oil produced during the entire development period (3233,472 days) of the field is determined by the formula
Σ Q _n = Q _anv. + Q _n = 134026.4 + 3134.45 = 137160.85 t ≈137.2 thousand tons

The amount of water produced during progressive flooding is determined by the formula
Q _in = Q _w -Q _n = 189320.8-3134.45 = 186186.35 t≈186.2 thousand tons

 Since, according to the claimed method, water breakthrough into the well along the roof and the bottom of the formation will occur simultaneously, the well operation time with progressive watering, and, consequently, 186.2 thousand tons of water produced during this period, is excluded from the development of the reservoir.

The decrease in the development time of the reservoir Δt in comparison with the prototype is determined by the formula
Δ = t _p ¹ -t ¹ = 3233.472-1371.580 = 1861.892 days ≈ 5 years.

 Thus, the opening of the reservoir by the proposed method will reduce the development time of the reservoir during oil displacement by 5 years and eliminate the production of water in the amount of 186.2 thousand tons

Example N 2
Characterization of a hypothetical reservoir exposed by multilateral wells
Depth of bed H _pl , m - 2000
True formation thickness h, m - 10
Formation angle α _pl , degrees - 10
The distance between the external and internal circuits of the KSS C, m - 57.6
Porosity of the reservoir, taking into account the utilization of the pore space m, fractions of units - 0.1
The flow rate of one production well q ₂ , m ³ / day. - 350
The final water cut of the production of production well B,% - 99
The distance between production wells in the row 2 σ, m - 500
The density of oil ρ, kg / m ³ - 850
When forming the profile of the wellbore, all technical operations are carried out as described in example No. 1.

The vertical projection of the depth of the multilateral well at the end of the horizontal section H _{G2 is} calculated by the formula
H _Г2 = S ₂ cos α + H
The radius of curvature of 190 m and the average intensity of curvature in this section, equal to 4.5 ^o per 10 m of penetration, provide an increase in the zenith angle of the wellbore on the roof of the reservoir up to 90 ^o . In the productive part of the reservoir, each horizontal section of the multilateral wellbore is drilled with an inclination angle of 0 ^o .

 The direction of drilling of each horizontal section of the multilateral wellbore in the reservoir is established as a result of a visual analysis of the structural map: the direction of the dip of the formation and the angle of its inclination at the drilling point, the position of the internal and external contours of the OWC are determined.

а их длину определяют по формуле

Вертикальная проекция глубины в конце горизонтального участка многозабойной скважины будет равна
H_Г2=S₂cos α + H=256cos90+2000=2000 м.A multilateral well is drilled in the reservoir so that the axes of each horizontal section of the bore form an angle β _m with the external and internal contours of the OWC, the value of which is determined from the expression

and their length is determined by the formula

The vertical projection of depth at the end of the horizontal section of the multilateral well will be equal to
H _Г2 = S ₂ cos α + H = 256cos90 + 2000 = 2000 m.

The horizontal projection of the displacement of the well at the end of the horizontal sections A _{G2 is} calculated by the formula
A _Г2 = S ₂ · sinβ _m + A = 256 · sin13 + 199 = 247.6 m.
The drilled horizontal sections of multilateral wells are oriented in the section of the productive formation parallel to the contact line of the OWC. And in terms of the formation, the axes of each horizontal section of the multilateral well bore form angles equal to 13 ^o with the external and internal contours of the OWC.

The characteristic of the technical result:
in the proposed method, the distance from each horizontal section of the multilateral wellbore along the roof and the bottom of the formation to the initial position of the OWC is the same (L ₁ = L ₁ ¹ ) and equal to 209 m

Скважина до полного обводнения будет работать 391,9 суток.The time of simultaneous breakthrough of water into the well along the roof and bottom of the formation, i.e. reservoir development time, determined by the formula

The well until full flooding will operate 391.9 days.

The amount of oil produced in 391.9 days is determined by the formula
Q _anc . ₁ = t ₁ ¹ · q ₁ = 391.9 · 350 = 137165 t ≈137.2 thousand tons

Comparison with prototype
Since the length of each horizontal section of the wellbore S ₂ in the proposed method for opening the formation is 256 m, the length of the horizontal section of the well in the prototype S _{2p is} also taken equal to 256 m. The angle formed by the horizontal section of the wellbore and the roof of the formation is 2 ^o . Then the length of the projection of the horizontal section of the wellbore onto the formation roof is determined by the formula
l ₂ = S _2n · cos2 = 256 · 0.9994 = 255.8 m.

The distance from each inclined section of the wellbore to the initial position of the oil well at the bottom of the formation L _{1p is} assumed to be 200 m (for the equal amount of oil contained between the initial position of the oil well and the wellbore, 137.2 thousand tons).

Время прорыва воды по подошве пласта t_1п определяют по формуле

Время прорыва по кровле пласта t_1п ¹, т.е. время разработки залежи, определяют по формуле

Скважина до полного обводнения будет работать 2364,69 суток.The distance from the well to the initial position of the OWC on the roof of the reservoir L _1p ¹ is determined by the formula

The time of water breakthrough at the bottom of the formation t _1p is determined by the formula

Breakthrough time over the top of the formation t _1p ¹ , i.e. reservoir development time, determined by the formula

The well until full flooding will work 2364.69 days.

The operating time of a well with progressive watering is determined by the formula
_pr1 t = t ¹ -t _{1P 1P} = 2364.69 = 2005.83 -358.86 day.

The amount of oil produced during the anhydrous period of the well for 358.86 days is determined by the formula
Q _{1P bezv.1} = t · q ₁ = 358.86 · 350 = 125601 tons.

The amount of fluid produced during the progressive watering of the well for 2005.83 days, is determined by the formula
Q _W.1 = t _pr1 · q ₁ = 2005.83 · 350 = 702040.5 t.

Учитывая плотность нефти, на 1 тонну нефти будет добываться 59,4 т воды или 60,4 т жидкости.The average water flow during the progressive watering of wells W is determined by the formula

Given the density of oil, 59.4 tons of water or 60.4 tons of liquid will be produced per 1 ton of oil.

Количество нефти, добытой за все время разработки (2364,69 суток) месторождения, определяют по формуле
Σ Q_н1=Q_безв1+Q_н1=125601+11623,19= 137224,18 т ≈137,2 тыс.т.The amount of oil produced during the progressive watering of the well is determined by the formula

The amount of oil produced during the entire development period (2364.69 days) of the field is determined by the formula
Σ Q _n1 = Q _bezv1 + Q _n1 = 125601 + 11623.19 = 137224.18 t ≈137.2 thousand tons

The amount of water produced during progressive flooding is determined by the formula
Q _b1 = Q _l.1 -Q _n1 = 702040.5-11623.19 = 690417.31 t ≈ 690.4 thousand tons

 Since, according to the claimed method, water breakthrough into the well along the roof and the bottom of the formation will occur simultaneously, the time of well operation with progressive watering, and, consequently, the amount of water produced in this period in the amount of 690.4 thousand tons is excluded from the time of developing the reservoir.

The decrease in the development time of the deposits Δt ₁ in comparison with the prototype is determined by the formula
Δ t ₁ = t _1п ¹ -t ₁ ¹ = 2364.69- 391.90 = 1972.79 days ≈5.4 years.

 Thus, the opening of the reservoir by the proposed method will reduce the development time of the deposit when oil is displaced by water by 5.4 years and exclude water production in the amount of 690.4 thousand tons

Even with the development of a second hypothetical reservoir with a single-hole horizontal well, the proposed method provides a positive technical result compared with the prototype: the development time of the reservoir Δ t ₂ will be reduced by
Δ t ₂ = t _1p ¹ -t ¹ = 2364.69-1371.58 = 939, 11 days ≈2.7 years.

 In addition, the production of water in the amount of 690.4 thousand tons is excluded.

Claims (1)

The method of opening a productive oblique bed with a pressure mode of hydrocarbon production, including drilling the productive formation from the roof to the bottom with single or multi-hole horizontal wells, characterized in that during the drilling process, the zenith angle of the wellbore on the roof of the reservoir is up to 90 ^o , horizontal sections of the trunks odnozaboynoy and multilateral wells are drilled with an inclination angle of 0 ^o, and by visual analysis of the structural card deposits in the case of a horizontal section of the well odnozaboynoy b ryat in a direction perpendicular to the outer or inner contours of gas-oil or water-oil contact (GOC and OWC), and its length is determined by the formula

where S ₁ - the length of the horizontal section of a single-well borehole in the reservoir, m;
h is the true thickness of the reservoir, m;
α _PL - the angle of inclination of the reservoir, deg.,
in the case of a multilateral well, horizontal sections of the well are drilled at an angle formed in the plan of the formation by the axis of each horizontal section with external or internal contours of the SOC or BOC, and determined from the expression

where β _m is the angle formed in the reservoir plan by the axis of each horizontal section of the wellbore with the external or internal contours of the SOC or BOC, deg .;
C is the distance between the external and internal circuits of the SOC or BOC, m;
σ - half the distance between production wells in a row, m,
and their length is determined by the formula

where S ₂ - the length of each horizontal section of the trunk of a multilateral well, m

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