RU2788182C1 - Method for developing oil deposits with low-permeability reservoirs - Google Patents

Abstract

FIELD: development of oil deposits.

SUBSTANCE: invention relates to a method for developing oil deposits with low-permeability reservoirs. The method for developing an oil deposit with low-permeability reservoirs includes determining the elements of occurrence, drilling a search well on the dome of seismic uplift. After drilling logging is conducted in the exploration wells, reservoir properties of reservoirs are determined, reservoir saturation with fluids, the boundaries of water-oil contact, economically viable recoverable oil reserves are estimated per horizontal well, the area of recoverable reserves per horizontal well is determined. A square grid is built with an area equal to the area of recoverable reserves per horizontal well. A square grid is built with an area equal to the sum of the areas of nine square cells arranged in three rows along the width and length of the square grid. Eight horizontal wells are built with the length of horizontal holes equal to the length of the diagonal of one square cell. Four horizontal wells with horizontal holes are located inside a square grid, directed diagonally across a square grid and faces located in the corners of a square grid or in the corners of a square cell located in the center of a square grid. There are four horizontal wells outside a square grid with horizontal holes directed perpendicular to the square grid, and faces in the center of each side of the square grid. On the structural map, the center of the square grid is combined with the face point of the drilled prospecting well. The first row of square grids is designed along the line of stretching of the structure to the boundaries of the water-oil contact with the distance between the square grids equal to the sum of two lengths of horizontal holes. Rows of square grids are designed with a distance between the rows equal to the length of the horizontal hole. Square grids are staggered parallel to the first row until the entire structure of the deposit of the development target is filled. The square grids by 22 °30^/ are rotated counterclockwise or clockwise in the first row relative to the line of the structure, then in each subsequent row rotate the square grids by 22 °30^/ in the opposite direction relative to the square grids of the previous row.

EFFECT: present invention enables to increase the efficiency of the development of oil deposits, in the uniformity of the production of oil reserves, in high rates of extraction of reserves of low-permeable reservoirs.

1 cl, 4 dwg

Description

The invention relates to the oil industry, namely the development of oil deposits contained in complex reservoirs with low permeability (less than 0.05 μm ² ), including carbonate reservoirs, tight sandstones, shale, chalk rocks, bazhenites.

A known method of cluster drilling of oil deposits based on horizontal and vertical wells (see Erokhin V.P., Shchavelev N.L., Naumov V.I., Fadeev E.A. Experience and problems in the construction of horizontal wells. Oil industry, No. 9 , 1997, pp. 32-35). According to this method, the drilling of an oil deposit is carried out according to an areal scheme, producing wells are constructed with horizontal wells, and injection wells - with vertical wells. In this case, well clusters are placed at the locations of injection wells.

The disadvantage of this method is the low technical and economic efficiency in fields with low-permeability reserves, associated with the drilling of a large number of wells, as well as the construction of a large number of well pads, equal to the number of injection wells, and therefore the cost of construction, as well as the corresponding infrastructure. And entailing negative impacts on the environment.

Also known is a method for developing an oil deposit with multilateral wells (patent RU No. 2330156, IPC E21V 43/16, publ. injection wells and selection of products from production wells. At the same time, drilling of at least one producing and one horizontal injection wells in formations with a permeability of not more than 2 mD and a distance between horizontal wellbores of at least 50 m is envisaged. Production wells are located in maximum oil-saturated thicknesses. The angle between the maximum principal stress of the formation and the direction of the horizontal wellbores of production and injection wells is from 30° to 60°. The number N of stages of multiple hydraulic fracturing is selected based on the condition N=1+L/100, where L is the length of the horizontal wellbore, and is rounded up to a larger integer. The total number of horizontal wells is drilled in the amount, on the basis that the specific initial geological oil reserves per one horizontal well are at least 50 thousand tons.

The disadvantage of this technology is the low technical and economic efficiency in fields with low-permeability reserves, associated with the risks of rapid watering of horizontal wells in more permeable interlayers and loss of recoverable reserves, with significant costs for drilling directional wells to produce the remaining pillars of oil.

The closest is the method of developing oil deposits with low-permeability reservoirs (patent RU No. 2760112, IPC E21V 43/30, 43/16, publ. 22.11.2021 in bull. No. 33), including the calculation of economically viable specific oil reserves for one horizontal design well , characterized in that, on the territory previously mapped by seismic work using the method of a common deep point, the elements of occurrence are determined - the arch, the strike line and the dip angle of the structure, an exploratory well is drilled on the arch of the seismic uplift, after calculating economically viable specific oil reserves for one horizontal design well, they determine the specific area of the deposit that provides one horizontal well with recoverable reserves, a square cell is built with an area equal to the area of the deposit that provides one horizontal well with recoverable reserves. Next, a grid is built with square cells with an area equal to the area of the deposit, providing one horizontal well with recoverable reserves, directional and horizontal wells are located, while first directional wells are drilled closest to the exploration well, then horizontal wells are drilled in the center of the square cells, formed by directional wells, and the horizontal wellbores are located in a perpendicular-cross direction to each other with the condition that the entry and bottomhole points of the horizontal wells correspond to the intersection points of the diagonals within one square cell, the bottomhole of the exploration well is aligned on the structure with the developed grid so that the exploration well was in the center of a square cell with horizontal wells, then by rotating around a vertical axis that passes through the location of the exploration well, the grid is oriented so that the horizontal wells are directed at an angle of 90° and 180° to the l the lines of the structure strike, the grid of wells ends with the location of the bottoms of directional wells to the contour of the oil-water contact.

The disadvantage of this method is the low technical and economic efficiency in fields with heterogeneous low-permeability reservoirs, associated with the restriction on the location of horizontal wells only at an angle of 90 ° relative to each other and an increase in the probability of skipping more permeable areas in the areal distribution of the lithologically heterogeneous reservoir of the development object.

The technical objectives are to increase the efficiency of the development of oil deposits with low-permeability reservoirs, the uniformity of the development of oil reserves, maintaining high rates of withdrawal of reserves of low-permeability reservoirs due to the optimal location of horizontal wellbores along the area of distribution of the oil-bearing formation, as well as expanding technological capabilities.

Technical problems are solved by the method of developing oil deposits with low-permeability reservoirs, including determining the elements of occurrence - arch, strike line and dip angle of the structure, drilling an exploratory well on the arch of a seismic uplift, calculating economically viable recoverable oil reserves per one horizontal design well.

What is new is that after drilling in an exploration well, geophysical surveys are carried out, the reservoir properties of the reservoirs, the saturation of the reservoirs with fluids, the boundaries of the water-oil contact are determined, the economically viable recoverable oil reserves per one horizontal design well are calculated, the area of recoverable reserves per one horizontal well is determined, then a square cell with an area equal to the area of recoverable reserves per one horizontal well, then a square grid is built, with an area equal to the sum of the areas of nine square cells arranged in three rows along the width and length of the square grid, then eight horizontal wells are built with a length of horizontal wells equal to the length of the diagonal one square cell, while four horizontal wells are located inside the square grid with horizontal wellbores directed along the diagonal of the square grid and bottomholes located at the corners of the square grid or at the corners of the square cell, running in the center of the square grid, as well as four horizontal wells with horizontal wellbores directed perpendicular to the square grid and bottomholes in the center of each side of the square grid outside the square grid, then on the structural map the center of the square grid is combined with the bottom hole point of the drilled exploratory well with the orientation of the outer horizontal wellbores of a square grid at an angle of 90° and 180° to the strike line of the structure, the first row of square grids is designed along the strike line of the structure to the boundaries of the oil-water contact with a distance between square grids equal to the sum of two lengths of horizontal wellbores, after which rows of square grids are designed with with a distance between rows equal to the length of the horizontal wellbore, while the square grids are staggered parallel to the first row until the entire structure of the deposit of the development object is filled, then the square grids are rotated by 22 ° 30 ^/ counterclockwise or clockwise in the first row relative to the stretch line of the structure, then in each subsequent row, the square grids are rotated by 22 ° 30 ^/ in the opposite direction relative to the square grids of the previous row.

Figure 1 shows a square grid layout with nine square cells and eight horizontal wells.

Figure 2 shows the arrangement of rows of square grids 1 in a checkerboard pattern parallel to the first row.

Figure 3 shows the arrangement of rows of square grids 1 with the orientation of each subsequent row at 22° 30 ^/ in the opposite direction relative to the previous row.

Figure 4 shows the layout of square grids and their orientation in the horizontal plane at the specified angles of rotation with placement in any plane of eight horizontal wells.

The method of developing oil deposits with low-permeability reservoirs is as follows.

Previously mapped by ground seismic works using the method of common deep point - CDP (for example, in 2D, 3D, 4D, etc.) the structure determines the occurrence elements - arch, strike line 1 (Fig.2-4) and the angle of incidence of the structure.

Next, a prospecting (or exploratory) well 2 (FIGS. 2-4) is drilled on the arch of the seismic uplift and geophysical surveys are carried out in it, including electrometric, radioactive, acoustic surveys. Based on the results of geophysical studies, reservoir properties of reservoirs are determined (recoverable oil reserves belong to the category of hard-to-recover, enclosed in reservoirs with a low permeability coefficient (less than 0.05 μm ² ), including carbonate reservoirs, tight sandstones, shale, chalk rocks, bazhenites ), fluid saturation of the reservoirs, the boundaries of the oil-water contact 3 (figure 2-4), calculate economically viable recoverable reserves per horizontal design well. After calculating economically viable recoverable oil reserves for one horizontal design well, the area of recoverable reserves for one horizontal well 4 is determined.

A square cell 5 is built with an area equal to the area of recoverable reserves per horizontal well 4 ^/ or 4 ^// .

Then a square grid 6 is built, with an area equal to the sum of the areas of nine square cells 5 arranged in three rows along the width and length of the square grid.

Next, eight horizontal wells 4 ^/ and 4 ^// are built with a length of horizontal wells equal to the length of the diagonal of one square cell 5.

At the same time, four horizontal wells 4 ^/ with horizontal wells directed along the diagonal of the square grid and bottomholes located at the corners of the square grid or at the corners of a square cell located in the center of the square grid are located inside the square grid 6, and four horizontal wells are also located outside the square grid. wells 4 ^// with horizontal shafts directed perpendicular to the square grid, and bottomholes in the center of each side of the square grid (figure 1).

Next, on the structural map, the center of the square grid 6 is combined with the bottom hole of the drilled exploration well 2 (Fig.2-4) with the orientation of the outer horizontal well bores 4 ^// square grid 6 at an angle of 90° and 180° to the strike line 1 (Fig.2 -4) structures.

Design the first row 7 (Fig.2-4) square grids 6 along the strike line 1 (Fig.2-4) structure to the boundaries of the oil-water contact 3 (Fig.2-4) with the distance between the square grids 6 equal to the sum of two horizontal lengths wellbores 4 ^/ or 4 ^// . After that, rows of square grids 6 are designed with a distance between rows equal to the length of the horizontal wellbore 4 ^/ or 4 ^// (figure 2).

At the same time, square grids 6 are placed in a checkerboard pattern parallel to the first row 7 until the entire structure of the deposit of the development object is filled.

Then rotate the square mesh 6 22° 30 ^/ counterclockwise or clockwise in the first row 7 relative to the line of extension of the structure 1 (figure 2-4), then in each subsequent row rotate the square mesh 6 22° 30 ^/ in the opposite direction relative to square grids 6 of the previous row, i.e. square grids 6 in the second row 8 (figure 2-4) are rotated by 22° 30 ^/ in the opposite direction relative to the square grids of the first row, in the third row 9 (figure 2-4) turn by 22° 30 ^/ relative to the second row 8 (Fig.2-4), etc.

This placement of square grids 6 and their orientation in the horizontal plane at a given angle of rotation allows you to place exactly eight horizontal wells 4 ^/ and 4 ^// (figure 4) in any plane, which is important for the uniform development of recoverable reserves of the deposit of the development object and provides each well 4 ^/ and 4 ^// sufficient oil reserves for payback and calculated profitability.

An example of practical application.

Preliminarily, on a structure mapped by ground seismic works using the common depth point method - CDP 2D, the occurrence elements were determined for a probable development object - a dome with an absolute elevation of -1050 m, a strike line 1 from east to west and a dip angle of the structure of 5 °.

Further, a exploratory well 2 was drilled on the arch of the seismic uplift and geophysical surveys were performed in it, including electrometric, radioactive, and acoustic surveys.

The reservoir properties of the reservoirs were determined, the permeability was 0.035 μm ² , the vertical oil-saturated thickness was 20 m, the reservoir type was carbonate, the absolute elevation of the oil-water contact was 3–1100 m, and the economically viable recoverable reserves per one horizontal design well were calculated, which amounted to 20 thousand tons of oil.

We determined the area of recoverable reserves per horizontal well 4 ^/ or 4 ^// equal to 160 thousand m².

We built a square cell 5 with an area of 160 thousand m², equal to the area of recoverable reserves per one horizontal well 4 ^/ or 4 ^// .

We calculated the length of the horizontal wellbore 4 ^/ or 4 ^// equal to the length of the diagonal of one square cell 5, which is 566 m.

Then a square grid 6 was built, with an area equal to the sum of the areas of nine square cells 5 arranged in three rows along the width and length of the square grid 6.

Next, eight horizontal wells 4 ^/ and 4 ^// were placed, while four horizontal wells 4 ^/ were located inside the square grid with horizontal wellbores directed along the diagonal of the square grid and bottomholes located at the corners of the square grid 6 or at the corners of the square cell 5 located in the center of the square grid 6, and located outside the square grid 6 four horizontal wells 4 ^// with horizontal shafts directed perpendicular to the square grid 6, and bottomholes in the center of each side of the square grid 6 (figure 1).

Further, on the structural map, the center of the square grid 6 was aligned with the bottom hole of the drilled exploratory well 2 with the orientation of the outer horizontal wellbores 4 ^// of the square grid 6 at an angle of 90° and 180° to the strike line 1 of the structure.

The first row of 7 square grids 6 was designed along the strike line 1 of the structure to the boundaries of the oil-water contact 3 with the distance between the square grids 6 equal to the sum of two lengths of horizontal wellbores 4 ^// . After that, rows of square grids 6 were designed with a distance between rows equal to the length of the horizontal wellbore 4 ^/ or 4 ^// (figure 2).

At the same time, square grids 6 were placed in a checkerboard pattern parallel to the first row 7 until the entire structure of the deposit of the development object was filled.

Then they turned the square grids 6 by 22° 30 ^/ counterclockwise or clockwise in the first row 7 relative to the strike line 1 of the structure, then in each subsequent row they turned the square grids by 22° 30 ^/ in the opposite direction relative to the square grids 6 of the previous row, i.e. e. the square grids in the second row 8 turned 22° 30 ^/ in the opposite direction relative to the square grids of the first row 7, in the third row 9 they turned 22° 30 ^/ relative to the second row 8, etc. (figure 3).

This placement of square grids and their orientation in the horizontal plane at a given angle of rotation made it possible to place in any plane exactly eight horizontal wells 4 ^/ and 4 ^// (figure 4), which is important for the uniform development of recoverable reserves of the deposit of the development object and provides each well 4 ^/ and 4 ^// sufficient volume of oil reserves for payback and calculated profitability.

EFFECT: method increases efficiency of development of oil deposits with low-permeability reservoirs, uniformity of oil reserves development, maintains high rates of low-permeability reservoirs recovery due to optimal location of horizontal wellbores over the area of distribution of an oil-containing formation, as well as expansion of technological capabilities.

Claims (1)

A method for developing an oil deposit with low-permeability reservoirs, including determining the occurrence elements - arch, strike line and dip angle of the structure, drilling an exploratory well on the arch of a seismic rise, calculating economically viable recoverable oil reserves for one horizontal design well, characterized in that after drilling in an exploratory well, geophysical surveys are carried out, the reservoir properties of the reservoirs, the saturation of the reservoirs with fluids, the boundaries of the water-oil contact are determined, the economically viable recoverable oil reserves per one horizontal design well are calculated, the area of recoverable reserves per one horizontal well is determined, then a square a cell with an area equal to the area of recoverable reserves per one horizontal well, then a square grid is built, with an area equal to the sum of the areas of nine square cells arranged in three rows along the width and length of the square grid, then eight horizontal wells are built with a length of horizontal wells equal to the length of the diagonal of one square cell, while four horizontal wells are located inside the square grid with horizontal wellbores directed along the diagonal of the square grid, and bottomholes located at the corners of the square grid or at the corners of the square cell, finding located in the center of the square grid, and four horizontal wells with horizontal wellbores directed perpendicular to the square grid and bottomholes in the center of each side of the square grid are located outside the square grid, then on the structural map the center of the square grid is combined with the bottom hole point of the drilled exploration well with the orientation of the outer horizontal wellbores of a square grid at an angle of 90° and 180° to the strike line of the structure, the first row of square grids is designed along the strike line of the structure to the boundaries of the oil-water contact with a distance between square grids equal to the sum of two lengths of horizontal wellbores, after which rows of square grids are designed with with a distance between rows equal to the length of the horizontal wellbore, while the square grids are staggered parallel to the first row until the entire structure of the deposit of the development object is filled, then the square grids are rotated by 22° 30^/ counterclockwise or clockwise in the first row relative to the line of strike of the structure, then in each subsequent row the square grids are rotated by 22° 30^/ in the opposite direction relative to the square grids of the previous row.

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