RU2795640C1 - Method for developing low permeability oil field - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention is related to a method for developing a low permeability oil field. Method for developing a low permeability oil field includes determination of the seismic uplift dome, the field line and the dip angle of the field. Prospecting or survey well is drilled on the seismic uplift dome and geophysical surveys are conducted in the well. The boundaries of the oil-water contact are identified. Economically viable specific oil reserves are determined for one horizontal design well. The specific area of the field is identified, which provides one horizontal well with recoverable reserves. A square cell is built with an area equal to the area of the field, providing one horizontal well with recoverable reserves. A square grid is built, consisting of nine square cells arranged three in three rows. In square cells located in the corners of a square grid, one vertical injection well is placed. In four square cells located on the sides of the square grid, one production horizontal well is placed with a horizontal wellbore length equal to the length of the diagonal of the square cell and a perpendicular direction of horizontal wellbores in rows. On the structural map, any vertical injection well of the grid is combined with the entry point of the borehole of the drilled prospecting or survey well, and the vertical injection well located on one side of the square grid with the combined vertical injection well is located in the direction of the field line. A plurality of square grids is placed along the field line until the entire field is filled length-wise, aligning the bottoms of vertical injection wells along the field line. The next row of square grids is designed parallel to the first row, combining the bottoms of injection wells until the rows of square grids cover the entire structure of the developed field. The producing horizontal design wells located beyond the boundary of the water-oil contact are removed, the field is delineated by vertical injection wells.

EFFECT: increasing the efficiency of the development of oil deposits with low permeability reservoirs by maintaining high recovery rates.

1 cl, 3 dwg

Description

The invention relates to the oil industry, namely the development of oil deposits with low-permeability reservoirs.

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 that the density of the grid of wells differs little from the options with vertical wells, the required number of wells is significant. The number of well pads is equal to the number of injection wells, that is, the number of such sites is large. Consequently, the costs for their construction, as well as for the corresponding infrastructure, are significant. Therefore, the impact on the environment is also significant.

Also known is a method for developing an oil deposit with multilateral wells (patent RU No. 2330156, IPC E21V 43/16, publ. 27.07.2008 in bull. 21), including drilling parallel production and injection horizontal wells, followed by multiple hydraulic fracturing, injection of a working agent into 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 disadvantages of this technology are the high risks of rapid flooding of horizontal wells along more permeable interlayers and the loss of recoverable reserves, the cost of drilling directional wells to produce the remaining pillars of oil. Also, the disadvantage is the low information content in the vertical section due to the lack of wells that have opened the entire oil-saturated section of the deposit.

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 determination of the seismic rise arch, the strike lines of the structure and the dip angle structures, drilling a prospecting or exploratory well on the arch of a seismic uplift and conducting geophysical surveys in it, determining the boundary of the water-oil contact, determining the economically viable specific oil reserves per one horizontal design well, determining the specific area of the deposit that provides one horizontal well with recoverable reserves, building a square cell an area equal to the area of the deposit, which 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 strike line of the structure, the grid of wells ends with the location of the bottomholes directional wells to the contour of the oil-water contact.

The disadvantage of this method is the low efficiency associated with the low oil recovery factor of low-permeability reservoirs, because transfer of directional production wells for injection, to maintain reservoir pressure in order to increase the oil recovery factor, increases the risk of sudden watering of nearby horizontal wells with such a layout of horizontal wells in combination with directional production wells. At the same time, this well placement scheme helps to maintain high rates of oil reserves recovery in the natural development mode with the maximum possible achievement of the oil recovery factor, without subsequent compaction.

The technical result is to increase the efficiency of the development of oil deposits with low-permeability reservoirs by maintaining high rates of extraction of reserves of low-permeability reservoirs due to a certain placement of wells, the creation of independent hydrodynamic areas for the development of a low-permeability field.

The technical result is achieved by a method for developing a low-permeability oil deposit, including determining the arch of a seismic uplift, the strike line of the structure and the dip angle of the structure, drilling a prospecting or exploratory well on the arch of a seismic uplift and conducting geophysical studies in it, determining the boundary of the water-oil contact, determining economically viable specific oil reserves per one horizontal project well, determination of the specific area of a deposit that provides one horizontal well with recoverable reserves, construction of a square cell with an area equal to the deposit area that provides one horizontal well with recoverable reserves.

What is new is that a square grid is built, consisting of nine square cells arranged three in three rows, in the square cells located in the corners of the square grid, one vertical injection well is placed, and in four square cells located on the sides of the square grid , are placed one horizontal production well with a horizontal wellbore length equal to the length of the diagonal of a square cell and a perpendicular direction of horizontal wellbores in rows, then on the structural map any vertical injection well of the grid is combined with the entry point of the borehole of the drilled exploratory or exploration well, and the vertical injection well located on one side of a square grid with a combined vertical injection well, are placed in the direction of the strike line of the structure, then the number of square grids is placed along the strike line until the entire deposit is filled in length, combining the bottoms of vertical injection wells along the strike line, then the next row of square grids is designed parallel to the first in a row, combining the bottomholes of the injection wells until the rows of square grids cover the entire structure of the deposit of the development object, the planned production horizontal wells located beyond the boundary of the water-oil contact are removed, with the deposit contoured by vertical injection wells.

In FIG. 1 shows a square grid layout consisting of nine square cells, with vertical injection wells and horizontal production wells.

In FIG. 2 shows the layout of project wells on the structure of the deposit before the removal of project production horizontal wells located outside the oil-water contact.

In FIG. 3 shows the layout of project wells on the deposit structure.

The method of developing low-permeability oil deposits is carried out as follows.

Preliminarily, on a structure mapped by ground seismic works using the common depth point method - CDP (for example, in 2D, 3D, 4D, etc.) the occurrence elements are determined - the arch of the seismic uplift, the strike line of the structure 1 and the dip angle of the structure.

Next, a prospecting or exploratory well 2 is drilled on the arch of the seismic uplift and geophysical studies are carried out in it, including electrometric, radioactive, acoustic studies.

Based on the results of geophysical surveys and occurrence elements, the boundaries of the water-oil contact 3 are determined and economically viable specific oil reserves per one horizontal design well are calculated.

The specific area of the deposit is determined, which provides one horizontal well with recoverable reserves.

A square cell 4 is built with an area equal to the area of the deposit, which provides one horizontal well with recoverable reserves.

Next, a square grid 5 is built, consisting of nine square cells 4, arranged three in three rows.

In square cells 4, located in the corners of the square grid, one vertical injection well 6 is placed, and in four square cells located on the sides of the square grid, one horizontal production well 7 is placed with a horizontal wellbore length equal to the length of the diagonal of the square cell and a perpendicular direction horizontal trunks in rows.

Further, on the structural map, any vertical injection well 6 of the grid is combined with the entry point of the borehole of the drilled exploration or exploration well 2.

The vertical injection well 6, located on one side of the square grid 5 with the combined vertical injection well 6, is located in the direction of the strike line of the structure 1.

Next, the number of square grids 5 is placed along the strike line 1 until the entire deposit is filled in length, combining the bottoms of vertical injection wells 6 along the strike line 1.

Then the next row of square grids 5 is designed parallel to the first row, aligning the bottomholes of vertical injection wells 6 until the rows of square grids 5 cover the entire structure of the deposit of the development object.

The design production horizontal wells 7 are removed, located outside the water-oil contact 3, with the delineation of the deposit by vertical injection wells 6.

The placement of wells 6, 7 in a square grid 5 and the distribution of square grids 5 over the reservoir area reduces the risk of a quick breakthrough of the injected fluid to the horizontal wellbore due to the combination of drainage zones of parallel horizontal wells in each independent hydrodynamic grid of low-permeability field development, allowing to maintain high the rate of oil recovery over the entire area of the deposit.

An example of practical application.

Preliminarily, on a structure mapped by ground seismic works using the common depth point method - CDP in a 2D structure, the occurrence elements were determined - the arch of the seismic uplift, the strike line of structure 1 and the dip angle of the structure.

Further, a prospecting well 2 was drilled on the arch of the seismic uplift and geophysical studies were carried out in it, including electrometric, radioactive, acoustic studies.

Based on the results of geophysical studies and occurrence elements, the boundaries of oil-water contact 3 were determined and economically viable specific oil reserves per one horizontal design well were calculated, which amounted to 20 thousand tons. The specific area of the deposit, which provides one horizontal well with recoverable reserves, was 160 thousand m².

We built a square cell 4 with an area of 160 thousand m² on the scale of the structural map.

Next, a square grid 5 was built, consisting of nine square cells 4, arranged three in three rows.

In square cells 4 located in the corners of the square grid, one vertical injection well 6 was placed, and in four square cells located on the sides of the square grid, one production horizontal well 7 was placed with a horizontal wellbore length equal to the length of the diagonal of the square cell and a perpendicular direction horizontal trunks in rows.

Further, on the structural map, one vertical injection well 6 of the grid was combined with the entry point of the borehole of the drilled exploration well 2.

The vertical injection well 6, located on one side of the square grid 5 with the combined vertical injection well 6, was placed in the direction of the strike line of the structure 1.

Next, the number of square grids 5 was placed along the strike line 1 until the entire deposit was filled in length, combining the bottoms of vertical injection wells 6 along the strike line 1.

Then, the next row of square grids 5 was designed parallel to the first row, combining the bottoms of vertical injection wells 6 until the rows of square grids 5 covered the entire structure of the deposit of the development object.

The planned production horizontal wells 7, located outside the water-oil contact 3, were removed, with the delineation of the deposit by vertical injection wells 6.

Thus, the proposed method increases the efficiency of low-permeability oil reservoir development by maintaining high rates of low-permeability reservoirs recovery and eliminates uneven advancement of the displacement front due to a certain placement of injection wells relative to horizontal production wells, creating independent block hydrodynamic pockets of low-permeability field development.

Claims (1)

A method for developing a low-permeability oil deposit, including determining the seismic uplift arch, the structure strike line and the structure dip angle, drilling a prospecting or exploratory well on the seismic uplift arch and conducting geophysical surveys in it, determining the boundary of the oil-water contact, determining economically viable specific oil reserves per horizontal design well, determining the specific area of a deposit that provides one horizontal well with recoverable reserves, constructing a square cell with an area equal to the area of the deposit that provides one horizontal well with recoverable reserves, characterized in that a square grid is built, consisting of nine square cells arranged three by three row, in square cells located at the corners of the square grid, one vertical injection well is placed, and in four square cells located on the sides of the square grid, one horizontal production well is placed with a horizontal wellbore length equal to the length of the diagonal of the square cell and perpendicular to the direction of the horizontal wells in rows, then on the structural map any vertical injection well of the grid is combined with the entry point of the borehole of the drilled prospecting or exploration well, and the vertical injection well located on one side of the square grid with the combined vertical injection well is located in the direction of the strike line of the structure, then the number of square grids is placed along the strike line until the entire deposit is filled in length, aligning the bottoms of vertical injection wells along the strike line, then the next row of square grids is designed parallel to the first row, aligning the bottoms of injection wells, until the rows of square grids cover the entire structure of the deposit of the development object , remove the design producing horizontal wells located beyond the boundary of the oil-water contact, with the delineation of the deposit by vertical injection wells.

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