RU2839493C1 - Method for development of multi-formation oil deposits with circular production well in middle of element and horizontal injection wells - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to a method for development of multi-formation oil deposits with a circular production well in the middle of the section and horizontal injection wells. Method includes geophysical researches in wells and determination of section of multi-formation deposit with interlayers coinciding in the structural plan, and determination of formation pressure, which in each of interlayers excludes hydrodynamic connection between them at connection. Method also includes collecting oil samples for analysis. At the selected section, performing the horizontal injection wells drilling in parallel to the oil bearing outline and/or the manifold replacement lines and at distance of 80-100 m inside the deposit from the oil bearing outline and/or the manifold replacement lines, bottomhole of the previous well and the point of entry into the formation of the next well are placed at distance of 200-250 m from each other. Horizontal borehole is drilled with length of 2.2-2.5 of distances of the approved grid of wells and put into operation. When formation pressure drops by 15-20% from the initial value and/or when horizontal wells started for production are watered, more than 97% of them are switched to injection. In central part of selected section, drilling of circular production well is performed with entry into formation and angle set of 3.5-4°, with exit to circumscribing circle radius of 250-300 m, with deep perforation. Each perforation hole is spaced from the previous one by not more than 8 m. Well bottom is as close as possible to the circular shaft and not more than 40-50 m from it, in this case having 42-50 holes arranged evenly along the well shaft along a spiral with depth of 1.5-2 m, and each with a varying direction of perforation as the producing shaft deepens, controlling the wellbore according to the GIS, carried out after its drilling so that in the upper and/or upper interlayers the perforation and/or perforations are oriented downwards at an angle to wellbore 50-60°. In the following interlayers, changing the angle before flattening to the horizontal and further raising the direction of the perforation hole to overlying and/or above-lying interlayers, while maintaining a circular well radius of 200-250 m from the inlet point to the bottomhole, and with a branch from injection horizontal wells located parallel to the oil bearing circuit and/or the manifold replacement lines, at 250-300 m from them to prevent breakthrough of injection agent to producing perforated spines of shaft and to production shaft and possibility of maximum oil production at deposit section by pumping displacement agent into injection horizontal wells. Displacement fluid is pumped into horizontal injection wells and products are extracted from circular production well. During operation oil and water production and injection are measured.

EFFECT: increasing oil displacement efficiency, increasing recovery of oil reserves both in square area and in section.

1 cl, 1 dwg

Description

The invention relates to the oil industry, namely to the development of oil deposits whose productive strata consist of several interlayers that coincide structurally.

A method for developing a heterogeneous oil field is known (patent RU No. 2101475, IPC E21B 43/20, published 10.01.1998), which provides for drilling a design number of injection and production wells, flooding and extracting oil to the surface, followed by drilling additional wells that take into account the volumetric heterogeneity of the formation, which is determined based on the results of field operation and modeling. Additional wells are drilled with a horizontal wellbore or horizontal wellbores are drilled from old wells, with horizontal wellbores being carried out along a line connecting stagnant oil pillars, and in the presence of replacement zones, lenses, dead-end zones or zones with low reservoir properties - along a line connecting these zones.

The disadvantage of this method is that it does not allow the entire oil deposit to be covered by the impact, as a result of which the oil recovery of the deposit remains at a low level.

The closest in technical essence and achieved result is the method of developing small deposits and individual lenses of an oil field (patent RU No. 2447271, IPC E21B 43/20, published on 10.04.2012), including drilling horizontal injection wells parallel to the oil-bearing contour and/or reservoir substitution lines and at least 70 m inside the deposit from the said lines in the plan, the bottomhole of the previous well and the entry point into the formation of the subsequent well are located at a distance from each other of at least 50 m, the horizontal borehole is drilled at least 2 distances of the approved well grid, when the formation pressure decreases below 80% of the initial value and/or when horizontal wells launched for production become flooded, more than 90% of them are transferred to injection, displacing oil to the center of the deposit and from the substitution zones to the non-reservoir to the reservoir development zone.

The disadvantage of this method is the high costs of drilling horizontal wells; part of the productive strata along the section of the main horizontal wellbore remains undrained and does not provide effective displacement.

The technical objectives of the proposed invention are to increase the efficiency of production (increase the recovery factor) of small multi-layer oil deposits, the layers of which have approximately equal formation pressures, by constructing wells taking into account the permeabilities of the layers and leveling the displacement front in sections of the deposit consisting of layers of different permeability, and increasing the injectivity profiles of low-permeability layers.

The specified task is achieved by a method of developing a section of multi-layer oil deposits with a circular production well in the middle of the section and horizontal injection wells, which provides for drilling injection and production wells, extraction of products through production wells, and injection of a working agent through injection wells.

What is new is that geophysical studies are carried out in wells and, based on the results, a section of a multi-layer deposit with interlayers that coincide in the structural plan is determined, then the reservoir pressures are determined at each of the interlayers, excluding the hydrodynamic connection between them during communication, corresponding to the permeability interlayers, oil samples are taken for research, then, in the selected section, horizontal injection wells are drilled parallel to the oil-bearing contour and/or the reservoir substitution lines and at a distance of 80-100 m inside the deposit from the oil-bearing contour and/or the reservoir substitution lines, the bottomhole of the previous well and the entry point into the formation of the subsequent well are located at a distance of 200-250 m from each other, a horizontal wellbore is drilled with a length of 2.2-2.5 distances of the approved well grid and launched for production, after the reservoir pressure has decreased by 15-20% from the initial and/or when horizontal wells launched for production are flooded, more than 97% are transferred to injection, in the central part of the selected area a circular production well is drilled with an entrance into the formation and a set angle of 3.5°-4° and with an exit to a radius of the describing circle of 250-300 m, with deep perforation, with each perforation hole being no more than 8 m from the previous one, and the bottom of the well is as close as possible to the circular wellbore and no more than 40-50 m from it, having in this case 42-50 holes located evenly along the wellbore in a spiral with a depth of 1.5-2.0 m, and each with a changing direction of perforation as the production wellbore deepens, monitoring the wellbore according to the well logging carried out after the end of its drilling so that in the upper and/or upper interlayers the perforation and/or perforation holes are oriented downwards at an angle to the wellbore 50°-60°, in the following interlayers the angle is changed until it flattens out to the horizontal and then the direction of the perforation hole rises to the overlying and/or overlying interlayers, maintaining the radius of the circular well from the entry point to the bottomhole of 200-250 m and with a departure from the horizontal injection wells located parallel to the oil-bearing contour and/or the reservoir substitution lines, by 250-300 m from them, then the displacement fluid is injected into the horizontal injection wells and the products are extracted from the circular production well, measurements of oil, water production and injection are taken during operation.

The figure shows a diagram of the method implementation.

The method is carried out in the following sequence.

Geophysical studies are carried out in wells and, based on the results, section 1 (Fig.) of a multi-layer deposit with interlayers that coincide in the structural plan is determined and the formation pressures are determined, which for each of the interlayers exclude a hydrodynamic connection between them during communication, corresponding to the permeability interlayers, and oil samples are taken for research.

In the selected area, horizontal injection wells 2 are drilled parallel to the oil-bearing contour and/or the reservoir substitution lines and at a distance of 80-100 m inside the reservoir from the oil-bearing contour and/or the reservoir substitution lines, the bottomhole of the previous well and the entry point into the formation of the subsequent well are located at a distance of 200-250 m from each other, a horizontal wellbore is drilled with a length of 2.2-2.5 distances of the approved well grid and launched for production. After the formation pressure has decreased by 15-20% from the initial and/or when horizontal wells launched for production are flooded, more than 97% of them are transferred to injection.

In the central part of the selected area, a circular production well 3 is drilled with an entrance into the formation and a set angle of 3.5° - 4°, with an exit to a radius of the describing circle of 250-300 m, with deep perforation, wherein each perforation hole is no more than 8 m away from the previous one, and the well bottom is as close as possible to the circular wellbore and no more than 40-50 m from it, having in this case 42-50 holes located evenly along the wellbore in a spiral with a depth of 1.5-2.0 m, and each with a changing direction of perforation as the production wellbore deepens, monitoring the wellbore according to the well logging carried out after the end of its drilling so that in the upper and/or upper interlayers the perforation and/or perforation holes are oriented downwards at an angle to the wellbore of 50°-60°, in the following interlayers change the angle until it flattens out to the horizontal and subsequently rises the direction of the perforation hole to the overlying and/or overlying interlayers, maintaining a radius of 200-250 m from the entry point to the bottomhole, and with a departure from the horizontal injection wells located parallel to the oil-bearing contour and/or the reservoir substitution lines, by 250-300 m from them to prevent a breakthrough of the injection agent to the producing perforation spikes of the wellbore and to the producing wellbore itself and the possibility of maximum oil production in the reservoir section by pumping the displacing agent into the horizontal injection wells.

Displacement fluid is injected into horizontal injection wells and production is extracted from circular production wells. During operation, measurements of oil and water production and injection are taken.

An example of specific implementation.

A multi-layer terrigenous deposit is being developed in the terrigenous carboniferous deposits at a depth of 1158 m. The deposit has been drilled with vertical, directional and horizontal wells according to the design grid with a distance between wells of 550 m. The initial reservoir pressure of the productive layer is 12 MPa, the permeability varies within the range of 0.203-0.498 μm ² , the oil saturation of the reservoir varies within the range of 74-83%. The oil-saturated thickness of the productive layer is 12 m.

In section 1 of the deposit (Fig.), drilling and construction of horizontal injection wells 3 are carried out parallel to the contour and 80 m from it at a distance of 200 m from each other. The length of the horizontal wellbore is 750 m, i.e. 2.5 distances of the approved well grid. Horizontal injection wells are developed as production wells. During operation, measurements of oil, water production, and reservoir pressure are taken.

After two years of development, the water cut of horizontal injection wells launched for production increased to 98% and the current reservoir pressure decreased to 10.1 MPa.

Drilling and construction of a circular production well 2 is carried out in the central part of the selected section 1 with an entrance to the formation and a set angle of 4°, with an exit to a radius of the circumscribing circle of 250 m with deep perforation, with each perforation hole being no more than 8 m away from the previous one, with the well bottom being as close as possible to the circular wellbore and 40 m away from it, having in this case 45 holes located evenly along the wellbore in a spiral with a depth of 1.8 m and each with a changing direction of perforation as the production wellbore deepens, monitoring the wellbore according to the well logging carried out after the end of its drilling so that in the upper and/or upper interlayers the perforation and/or perforation holes are oriented downwards at an angle to the wellbore of 60° in the following interlayers the angle is changed until flattening to the horizontal and subsequently raising the direction of the perforation hole to higher the underlying and/or overlying interlayers, maintaining a circular wellbore radius of 250 m from the entry point to the bottomhole, and with a departure from the horizontal injection wells located parallel to the oil-bearing contour and/or the reservoir substitution lines, no more than 300 m from them to prevent a breakthrough of the injection agent to the producing perforation spikes of the wellbore and to the producing wellbore itself and the possibility of maximum oil production in the reservoir area by pumping the displacing agent into the horizontal injection wells.

Displacement fluid is injected into horizontal injection wells and production is carried out from a circular production well.

The use of the proposed method will allow for a maximum increase in the oil displacement coefficient and a significant increase in the production of oil reserves both by area and by section.

Claims (1)

A method for developing a section of multi-layer oil deposits with a circular production well in the middle of the section and horizontal injection wells, including drilling injection and production wells, collecting products through the production wells, pumping a working agent through the injection wells, characterized in that geophysical studies are carried out in the wells and, based on the results, a section of the multi-layer deposit with interlayers that coincide in the structural plan is determined, then the formation pressures are determined at each of the interlayers, excluding the hydrodynamic connection between them during communication, corresponding to the permeability interlayers, oil samples are collected for research, then, in the selected section, horizontal injection wells are drilled parallel to the oil-bearing contour and/or the reservoir substitution lines and at a distance of 80-100 m inside the deposit from the oil-bearing contour and/or the reservoir substitution lines, the bottomhole of the previous well and the entry point into the formation of the subsequent well are located at a distance of 200-250 m from each other, a horizontal wellbore is drilled with a length of 2.2-2.5 distances of the approved well grid and launched for production, after the reservoir pressure has decreased by 15-20% from the initial and/or when horizontal wells launched for production are flooded, more than 97% of them are transferred to injection, in the central part of the selected area a circular production well is drilled with an entrance to the reservoir and a set of angles of 3.5°-4° and with an exit to a radius of the describing circle of 250-300 m, with deep perforation, and each perforation hole is no more than 8 m from the previous one, and the bottom of the well is as close as possible to the circular wellbore and no more than 40-50 m from it, having in this case 42-50 holes located evenly along the wellbore in a spiral with a depth of 1.5-2.0 m, and each with a changing direction of perforation as deepening of the production shaft, monitoring the wellbore using GIS, conducted after completion of its drilling so that in the upper and/or upper interlayers the perforation and/or perforation holes are oriented downwards at an angle to the wellbore of 50°-60°, in the following interlayers the angle is changed until it flattens out to the horizontal and then the direction of the perforation hole rises to the overlying and/or overlying interlayers, maintaining a radius of 200-250 m from the entry point to the bottomhole of the circular well and with a departure from the horizontal injection wells located parallel to the oil-bearing contour and/or reservoir substitution lines by 250-300 m from them, then the displacement fluid is injected into the horizontal injection wells and production from the circular production well is produced, measurements of oil production, water and injection are carried out during operation.