RU2569520C1 - Method of development of oil deposits - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method vertical wells are drilled and five-point development elements are formed with injectors located at corners of the development elements and producers located in the centre. Drilling is performed within limits of each development element of dual horizontally brunched wells (HBW) with rounded borehole ending. Working fluid is injected through injectors. Product is extracted through producers. At that in the deposit with to oil-bearing interlayers all vertical wells are drilled with penetration of these interlayers. Each development element is made with length of the edge equal to 4L, where L is quarter of distance between vertical injectors. From the central part of two opposite edges of the development element dual producing HBW are drilled. There boreholes are led in different directions towards inner side of the development element along circumference with radius 2L. Length of each borehole of the producing HBW is made equal to (0.9-1.l)·π·L, where π=3.14. From points formed at crossing in plane of conventional lines drawn from entries of producing HBW to the stratum and injectors at opposite edges of the development element dual injecting HBW are drilled. Boreholes are led in different directions towards inner part of the development element along circumference with radius L. Length of each borehole of injecting HBW is made equal to (0.3-0.5)·π·L. Each horizontal borehole is made in different oil-bearing interlayers. Parallel boreholes of producing and injecting HBW are also performed in different oil-bearing interlayers. Water-swellable packer is placed in the central part of each borehole of the producing HBW. Each injector is burned off for oil extraction for the period not exceeding three years.

EFFECT: increasing sweep efficiency and oil recovery rate from productive stratum of the oil deposit.

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Description

The way to develop oil deposits

The invention relates to the oil industry and can find application in the development of oil deposits, productive reservoirs of which consist of two layers, which coincide structurally.

A known method of developing an oil reservoir, including drilling a reservoir with horizontal and vertical wells along a square grid and forming elements by drilling in the center of an element of a vertical and / or directionally directed injection well, drilling multilateral wells producing horizontal wells on the sides of the elements, injecting the working reagent through the injection wells cyclically and selecting products through production wells, measurements of oil, water and injected fluid, conducting hydrodynamic studies dovany and maintaining reservoir pressure at the level of the original selection area. In the known method, before drilling the deposits, areas with total oil-saturated thicknesses of more than 13 m in carbonate reservoirs and / or areas with effective oil-saturated thicknesses of at least 3 m in the oil zone and at least 5 m in the oil-water zone in terrigenous reservoirs are drilled, vertical and / or a directionally directed injection well in the center of each element, the sides of each element are closed with multilateral wells with a horizontal end in the form of semicircles, each of which covers half of the element, with about a bottom ascending branch in the middle of the semicircle, directed to the corner of the element for producing oil reserves in the underfloor part of the reservoir, replacing two horizontal or three vertical and / or directional wells in the element along the sides and corners of the elements, the displacing working reagent is injected through the injection well into the lower part of the productive interval cyclically, determine the optimal injection period at which the maximum pressure recovery in the selection zone and the expression of oil from the matrix (RF patent No. 2439299, cl. E21 B43 / 20, publ. 01/10/2012).

The disadvantage of this method is the low oil recovery of the reservoir due to the fact that 1/4 of the reservoir area remains unreached.

Closest to the proposed invention in technical essence is a method of developing an oil reservoir, including determining the direction of fracture of the reservoir, forming elements by drilling horizontal injection wells on a square grid with parallel arrangement of trunks and multilateral wells with rounded ends of the trunks located around the trunk of each horizontal well, injection working agent through injection wells and product selection through production wells with wells, when watering the latter, determination of watering intervals and isolation of waterlogged intervals. In the known method, a multilateral well is made in the form of a semi-ellipse, the major axis a of which is directed at an angle of 30-60 ° to the direction of fracture with a ratio of the minor semiaxis b / 2 to the semimajor axis a / 2 of the ellipse 0.1-0.8, while the trunks are multilateral production wells are performed in the productive part of the formation (0.6-0.8) · a each long, on which water swellable packers are installed every 50-250 m, and the trunks themselves are placed at the top of the productive formation at a distance of at least 0.5 m no more than 2 m from it, horizontal injection well in plan along the major axis a of the ellipse of the multilateral well, perform the length (0.3-0.6) · a of the horizontal part in the reservoir and place them at the water-oil contact or the sole of a purely oil-saturated formation at a distance of at least 0.2 m and no more than 1 m from it. Additionally, horizontal wells are drilled after drilling for oil until the reservoir pressure drops to 0.7 from the initial one, after which multilateral wells are drilled, and horizontal ones are transferred for injection of the working agent (RF patent No. 2513216, class E21 B43 / 20, E21 B33 / 12 , publ. 04/20/2014 - prototype).

The known method allows to increase oil recovery, however, in the presence of several oil-saturated interlayers, the coefficient of coverage of the formation in thickness remains low, which leads to a low oil recovery coefficient (CIN). Also, the predominant direction of cracks is not always possible to establish, because in most cases, the directions of the cracks are chaotic.

In the proposed invention solves the problem of increasing the coefficients of coverage and oil recovery of the productive reservoir of oil deposits.

The problem is solved in that in the method of developing oil deposits, including the drilling of vertical wells and the formation of five-point elements with injection wells in the corners of the elements and production wells in the center, drilling within each element of double-barreled multilateral horizontal wells (MZGS) with rounded shaft ends, injection of the working agent through injection wells and product selection through production wells, according to the invention, a reservoir with two oil-saturated layers is selected, all vertically Both wells are drilled with the opening of both layers, each element is made with a face length of 4L, double-barrel producing MZGS are drilled from the central part of two opposite faces of the element, with the trunks being carried out in different directions inside the element along a circle with a radius of 2L, the length of each trunk of the producing MZGS is equal to ( 0.9 ... 1.1) · π · L, from double points formed at the intersection in terms of conditional lines drawn from the entry points into the formation of the producing MZGS and injection wells on opposite sides of the element, double-barreled injection MZGS, moreover, the trunks are carried out in different directions to the inner part of the element along a circle of radius L, the length of each barrel of the injection MZGS is equal to (0.3 ... 0.5) · π · L, each horizontal trunk is carried out in different oil-saturated interlayers, and parallel The trunks of the producing and injection MLHGs are also carried out in different oil-saturated interlayers, a water-swelling packer is placed in the central part of each trunk of the producing MLHG, each injection well has been worked out for oil for no more than three years.

SUMMARY OF THE INVENTION

The oil recovery of an oil reservoir, the productive layer of which consists of two layers separated by a non-reservoir, is significantly affected by the coverage of the reservoir with an impact. The non-collector interlayer is heterogeneous in thickness; in some parts of the reservoir, its thickness can decrease to zero. In this regard, the upper and lower oil-saturated layers to some extent affect each other. Existing technical solutions do not fully allow the selection of oil from the reservoirs of a similar reservoir using MZGS. In the proposed invention solves the problem of increasing the coefficients of coverage and oil recovery of the productive reservoir of oil deposits. The problem is solved as follows.

In FIG. 1-3, respectively, the layout of wells in the reservoir area with the allocation of development elements, the layout of the element in the plan and the profile of production and injection wells are presented. Accepted designations: 1 - oil field section, 2-5 - vertical injection wells, 6 - vertical production well, 7-8 - production gas supply tanks, 9-10 - pressure gas supply wells, L - distance between vertical injection wells 2-5 (1 / 4 distances of the face of the element), 11-14 - conventional lines drawn from the places of entry into the reservoir of the producing MZGS 9-10 and injection vertical wells 2-5 on the opposite faces of the element, B is the upper oil-saturated interlayer, N is the lower oil-saturated interlayer.

The method is implemented as follows.

In the oil reservoir 1 (Fig. 1), the productive reservoirs of which consist of two interlayers B (upper) and H (lower) (Fig. 2), structurally identical, they drill vertical wells along a rare grid using a five-point development system. Each element consists of four injection wells in the corners of the element and one production well in the center. All vertical wells are drilled with the opening of both layers B and N. Elements perform a face length equal to 4L.

Consider one element (Fig. 3). The distance between the vertical injection wells 2-5 is 4L. The distance between the vertical production well 6 and the injection wells 2-5 is 2√2 · L.

From the central part (in the plan) of the two opposite faces of the element, double-barreled mining MZGS 7 and 8 are drilled. The length of each barrel of the producing MZGS 7 and 8 is equal to (0.9 ... 1.1) · π · L.

From the point formed at the intersection in terms of conditional lines 11 and 12, drawn from the point of entry into the reservoir of the producing MZGS 7 and 8 and injection wells 2 and 5 on opposite sides of the element, a double-barrel injection MZGS 9 is drilled. Similarly, from the point formed at the intersection at plan conventional lines 13 and 14, drawn from the entrance to the reservoir producing MZGS 7 and 8 and injection wells 3 and 4 on opposite sides of the element, drill double-barrel injection MZGS 10. Trunks MZGS 9 and 10 are conducted in different directions to the inner part of the element the circumference of a circle of radius L. The length of each barrel of the injection MZGS 9 and 10 is equal to (0.3 ... 0.5) · π · L.

According to studies, such a shape of the wells 7-10 in the form of semicircles allows to achieve maximum coverage of the formation by area, and the parallel placement of injection wells 9 and 10 relative to the production wells 7 and 8 increases the displacement efficiency. If the collector has natural cracks, then the circular arrangement of wells, according to the invention, can minimize the effect of cracks, the directions of which in most cases are chaotic. The direction of the trunks MZGS 7-10 in the element and their equal length as much as possible reduces the stress that occurs when bending the trunks. While significant stresses reduce the overhaul period of wells.

The length of the shafts of the producing MZGS 7 and 8 is calculated as ¼ of the circumference of the circle inscribed in the element in question with dimensions 4Lx4L, i.e. ¼ · 2 · π · 2L = π · L. Studies have shown that ± 10% of this length has virtually no effect on the coverage and oil recovery of the reservoir. With a trunk length of less than 0.9 · π · L, coverage is reduced, and more than 1.1 · π · L - does not increase oil recovery, while capital costs for drilling increase. Therefore, each wellbore 7 and 8 perform a length of (0.9 ... 1.1) · π · L.

The length of the injection trunks 9 and 10 are calculated as ¼ of the circumference inscribed in ¼ of the element in question (squared with dimensions 2Lx2L), i.e. ¼ · 2 · π · L = 0.5 · π · L. Studies have shown that when the trunk length is more than 0.5 · π · L, the rate of watering of the products of the producing MZGS increases, and at less than 0.3 · π · L, the displacement efficiency and, accordingly, the recovery factor are reduced. Therefore, each wellbore 9 and 10 is performed with a length of (0.3 ... 0.5) · π · L.

Each horizontal wellbore is carried out in different oil-saturated interlayers B and H, and parallel wells of producing 7 and 8 and injection 9 and 10 MZGS are also carried out in different oil-saturated interlayers B and N. So, for the considered element, the two shafts of the producing well 7 are parallel to the left (in plan ) injection well shafts 9 and 10. For two production well shafts 8, the right injection well shafts 9 and 10 are parallel. Thus, if one, for example, the upper (in plan) well bore 7 is carried out along the lower N interlayer, then the lower lower wellbore 7 is carried out along the upper interlayer. At the same time, the left wellbore 9 is placed in the upper B interlayer, and the left wellbore 10 is in the lower N. The upper (in plan) wellbore 8 is drawn along the upper B interlayer, and the lower well along the lower N. The right wellbore 9 is placed in the lower N interlayers, and the right borehole 10 - in the upper B.

Studies have shown that the placement of production and injection wells in opposing interlayers can reduce the watering rate of production of production wells and increase the coverage of the formation in thickness.

Mining and injection MZGS are drilled similarly on the remaining elements (Fig. 1).

A water-swellable packer (for example, the TAM company) is placed in the central part of each trunk of the producing MZGS 7 and 8. In the event of a water breakthrough, the packer allows you to “disconnect” part of the trunk of the producing MZHS.

Each injection well 2-5 and 9-10 is worked out for oil for no more than three years. Mining time is determined by the presence of economically viable oil production. However, when operating in production for more than three years, reservoir pressure begins to decline. According to studies in most reservoirs (mainly carbonate), it is very difficult to restore it by water flooding after lowering the reservoir pressure. Therefore, mining is conducted no more than three years.

Depending on the geological and physical characteristics of the reservoir and the development stage, it is also possible to conduct cyclic or non-stationary flooding.

After drilling wells 2-10, they are equipped, stimulation is carried out, if necessary, and put into operation. They conduct production from the MZGS 7, 8 and the vertical well 6 and pump water into the injection MZGS 9, 10 and vertical wells 2-5.

The development is carried out until the full economically viable development of the deposit area 1.

The result of the implementation of this method is to increase the coefficients of coverage and oil recovery of the productive reservoir of oil deposits

Examples of specific performance of the method.

Example 1. On the site of oil reservoir 1 (Fig. 1), productive reservoirs of which are represented by pore-crack carbonate deposits and consist of two interlayers B (upper) and H (lower) (Fig. 2), structurally identical, vertical drillings are drilled along a rare grid wells using a five-point development system. Preliminary calculations determined the optimal distance L = 300 m. Each element consists of four injection wells in the corners of the element and one production well in the center. All vertical wells are drilled with the opening of both layers B and N. The elements are performed with a face length of 4L = 4 · 300 = 1200 m.

The reservoir of reservoir 1 lies at a depth of 900 m, the effective oil-saturated thickness of the upper interlayer B is 10 m, the lower interlayer N is 8 m. The average reservoir permeability is 85 mD, and the oil viscosity at reservoir conditions is 35 MPa · s.

Consider one element (Fig. 3). The distance between the vertical injection wells 2-5 is 4L = 1200 m. The distance between the vertical production wells 6 and the injection wells 2-5 is 2√2 · L = 2√2 · 300 = 849 m.

From the central part of two opposite faces of the element, double-barrel producing MZGS 7 and 8 are drilled. The trunks of the MZGS 7 and 8 are carried out in different directions inside the element along a circle with a radius of 2L = 600 m. The length of each barrel of the producing MZGS 7 and 8 is 0.9 · π · L = 848 m.

From the point formed at the intersection in terms of conditional lines 11 and 12, drawn from the point of entry into the reservoir of the producing MZGS 7 and 8 and injection wells 2 and 5 on opposite sides of the element, a double-barrel injection MZGS 9 is drilled. Similarly, from the point formed at the intersection at plan conventional lines 13 and 14, drawn from the entrance to the reservoir producing MZGS 7 and 8 and injection wells 3 and 4 on opposite sides of the element, drill double-barrel injection MZGS 10. Trunks MZGS 9 and 10 are conducted in different directions to the inner part of the element the circumference of a circle with a radius of L = 300 m. The length of each trunk of the injection MZGS 9 and 10 is 0.5 · π · L = 471 m.

The upper (in plan) wellbore 7 is carried out along the lower H interlayers, the lower wellbore 7 is carried out along the upper B interlayers. In this case, the left wellbore 9 is placed in the upper B interlayer, and the left wellbore 10 is in the lower N. The upper wellbore 8 is drawn along the upper B interlayer, and the lower well along the lower N. The right wellbore 9 is placed in the lower H interlayer, and the right borehole 10 is in the upper B.

Mining and injection MZGS are drilled similarly on the remaining elements (Fig. 1).

In the central part of each trunk of the producing MZGS 7 and 8, one TAM water-swellable packer is placed.

After drilling wells 2-10, they are equipped and put into operation. Each injection well 2-5 and 9-10 is worked out for oil for three years. They conduct production from the MZGS 7, 8 and the vertical well 6 and pump water into the injection MZGS 9, 10 and vertical wells 2-5.

Example 2. Perform, as example 1. The reservoir is represented by terrigenous deposits. In connection with other reservoir properties, it is determined that the optimal distance is L = 200 m. The length of each trunk of the producing MZGS 7 and 8 is 1.1 · π · L = 1.1 · 3.14 · 200 = 691 m. The length of each trunk injection MSGS 9 and 10 are equal to 0.3 · 3,14 · 200 = 188 m. Each injection well 2-5 and 9-10 is worked out for oil for one year. Cyclical flooding is carried out: water is injected into injection wells 2-5 and 9-10 with a period of 14 days injection and 14 days idle.

The development is carried out until the full economically viable development of the deposit area 1.

As a result of the development of one element, consisting of one vertical injection well (four ¼ parts of wells 2-5 in the corners of the element), one vertical production 6, two injection MZGS 9, 10 and two production MZGS 7, 8, which was limited by the flooding of production wells to 98%, 489 thousand tons of oil were produced, the coverage factor was 0.783, the recovery factor was 0.420. According to the prototype, ceteris paribus, 432 thousand tons of oil was produced, the coverage coefficient was 0.693, and the recovery factor was 0.371. The increase in oil recovery by the proposed method amounted to 0.049.

Thus, the proposed method provides an increase in oil recovery site deposits.

Application of the proposed method will allow to solve the problem of increasing the coverage and oil recovery coefficients of a productive reservoir of an oil reservoir.

Claims (1)

A method of developing oil deposits, including drilling vertical wells and forming five-point development elements with injection wells in the corners of the elements of development and production wells in the center, drilling within each development element of double-barreled multilateral horizontal wells - MZGS with rounded ends of the wells, pumping a working agent through injection wells and selection of products through production wells, characterized in that they select a reservoir with two oil-saturated layers, all vertical wells are drilled with the opening of both layers, each development element is made with a face length of 4L, where L is a quarter of the distance between the vertical injection wells, double-barrel production wells are drilled from the central part of two opposite faces of the development element, and the trunks are carried out in different directions inside the development element along a circle with a radius of 2L, the length of each trunk of the producing MLMG is equal to (0.9 ... 1, l) · π · L, where π = 3.14, from the points formed at the intersection in terms of conditional lines, prov data from the entry points into the reservoir of the producing MZGS and injection wells on opposite sides of the development element, double-barrel injection MZGSs are drilled, the trunks being carried out in different directions to the inside of the development element along a circle of radius L, the length of each barrel of the injection MZGS is equal to (0.3 ... 0.5) · π · L, each horizontal wellbore is carried out in different oil-saturated interlayers, and parallel shafts of the production and injection MZGS are also carried out in different oil-saturated interlayers, in the center noy part of each barrel mining MZGS place swellable packer, each injection well and spend the oil is not more than three years.

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