RU2382183C1 - Multi zone oil reservoir at late stage with unstable cover formation and non-homogeneous collector development method - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: essence of the invention: according to the method execute at least of a one hole drilling in a multi zone reservoir at the late stage with unstable cover formation and non-homogeneous collector. Drill though the cover unstable formation under an angle, not greater than drilling without crushing limit angle. Case the borehole, overlapping the cover unstable formation until producing member. Pass through the producing member non-homogeneous formation total interval with a bit of smaller diametre and angle set up to 90° to the bottom. Execute research, select formation with the greatest residual reserve and depth. Enter the selected formation with the following angle set. Exit at 90°, go through the formation sub-horizontally and/or horizontally by the formation most permeable sub-layer, staying in it, execute control according to geo-process research. At clay bridges and/or watered sub-layers presents case the well with a tail, from the producing member roof until the selected formation with residue reserves after execution an oil saturation research. Open only oil saturated formations, each in two formation cross sections. Execute selected formation hole sub-horizontal or/and horizontal part production through an opened hole of a filter, descending tubing pipes tail till the well borehole bottom part.

EFFECT: field oil recovery increase.

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Description

The invention relates to the oil industry and may find application in the development of a multilayer oil reservoir in the late stage with unstable rock formations and an inhomogeneous reservoir.

A known method of developing deposits of viscous and bituminous oils, in particular in formations with small thicknesses. The method includes the exploitation of deposits using horizontal wells. To prevent premature breakthrough of the displacing agent and increase oil recovery in the production well, passing in the bottom of the reservoir, increase the depth of the output of the well from the reservoir. To create a kind of oil shutter and to control the pressure in the gas cushion, the outer casing is perforated in the vertical part in the area of the formation roof. Moreover, the depth of the fluid shutter depends on the properties of the oil, the expected flow rate and reservoir pressure. Tubing with pump down to the bottom of the casing. Injection wells are parallel to the producing ones, spending the horizontal part in the roofing zone of the formation (RF patent No. 2082875, IPC ЕВВ 43/00, publ. June 27, 1997).

The known method allows you to select the main oil reserves from formations with a heterogeneous reservoir and small thicknesses, however, oil recovery remains at a low level due to incomplete coverage of the object by the impact.

Closest to the proposed invention in technical essence is a method of developing an oil reservoir in a heterogeneous reservoir of small thickness, according to which at least one well is laid under a productive formation and a horizontal section is put into the formation, the tubing string is lowered and the well is operated as mining or injection. According to the invention, after entering the formation, the horizontal section of the well is carried out in waves from the sole through the middle to the top of the formation and back from the roof through the middle to the bottom of the formation with the repetition of waves along the formation, the tubing string is brought into the reservoir, when the well is operated as producing production selection fluids lead along the entire profile of the well: from the bottom, middle and roof parts, when operating the well as an injection, the working agent is pumped along the entire profile of the well: into soil, middle and roofing parts of the formation (RF patent No. 2290498, IPC ЕВВ 43/16, publ. 12/27/2006).

The method allows to increase the displacement of oil due to coverage with the development of non-draining reserves within areas with unprofitable thickness. The disadvantage of this method is the low coefficient of oil recovery as a result of the fact that horizontal and subhorizontal wells are drilled in one of the layers along the section, and of small thickness, subjecting to conservation the reserves of other layers of the productive pack, thereby reducing oil recovery.

An object of the invention is to increase oil recovery by introducing into the development of residual non-drained oil reserves and increasing the coefficient of coverage by their production.

The problem is solved by the method of developing a multilayer oil reservoir in the late stage with unstable rock formations and an inhomogeneous reservoir, including at least one well being led along the section of the productive pack to the sole with subsequent exit to the formation, lowering the tubing string to the lowest point of the trunk well operation. What is new is that unstable tire rocks pass at an angle not exceeding the maximum penetration angle without plugging, the wellbore is cased, blocking unstable tire rocks, to a productive pack, the entire interval of heterogeneous productive pack rocks with a smaller bit diameter with a set angle of up to 90 ° the bottom of the pack, conduct research on oil saturation, select a formation with the largest residual oil reserves and oil-saturated thickness, with a subsequent set of angles enter the selected formation, go 90 °, etc. walk around the formation subhorizontal and / or horizontally, along the most permeable layer, do not leave the formation, and in the presence of clay bridges and / or aquifers, the distance from the roof of the productive pack of the selected reservoir with residual reserves after oil saturation studies is cased with a shank and only oil saturated reservoirs, each at two reservoir intersections, and the operation of the subhorizontal and / or horizontal parts of the trunk in the selected reservoir is carried out through an open trunk or filter with descent shank tubing to the bottom of the wellbore.

SUMMARY OF THE INVENTION

When developing a multilayer oil reservoir in the late stage with unstable tire rocks and a heterogeneous reservoir, in practice, the layers are unevenly developed. The additional development of residual oil reserves in such deposits is an urgent task. The oil recovery achieved during development by existing methods on a multilayer oil reservoir in the late stage of development, which has high heterogeneity both in area and in reservoir height, remains at a low level. The proposed method solves the problem of increasing oil recovery multilayer oil deposits in the late stage with unstable rocks of the tire and a heterogeneous reservoir. The problem is solved as follows.

When developing a multilayer oil reservoir in the late stage with an unstable rock formation and a heterogeneous reservoir, at least one well is drilled, unstable rock rocks are passed at an angle not exceeding the maximum angle of penetration without collapse, and the wellbore is capped, overlapping unstable rock rocks, to productive pack, cover the entire interval of heterogeneous rocks of the productive pack with a smaller bit diameter with a set angle of up to 90 ° to the bottom of the pack, conduct research on oil saturation , select the formation with the largest residual reserves and oil-saturated thickness, then set the angle to enter the selected formation, exit 90 °, pass the formation horizontally and / or horizontally along the most permeable layer in it, do not exit the formation, monitoring by geological and technological research (GTI), and in the presence of clay bridges and / or aquifers, the distance from the roof of the productive pack of the selected reservoir with residual reserves after conducting oil saturation studies is planted with needles tovikom and autopsied only oil-bearing strata in each of two plasto-intersections and subhorizontal operation and / or the horizontal part of the stem in the preferred formation lead through open hole or a filter with the descent of the shank of tubing to the bottom of the wellbore.

The limiting angle of penetration without blockage is determined by special core studies and depends on the strength of the rock breed.

With such an organization of wells, it is possible to solve the problem of oil selection from a productive pack of formations having heterogeneity both in area and in section. By the area of the reservoir, a horizontal section of the well is carried out in an area with residual oil reserves, providing coverage of the formation by the effect of the area. According to the thickness of the formation, the horizontal section of the well is carried out along the pack as a whole and along the reservoir selected in its section with the largest residual oil reserves and thickness, ensuring the maximum possible coverage of the pack and the formation by the effect of thickness.

The permeability in thickness can vary by an order of magnitude due to the clayiness of the bed and bottom of the formation. Therefore, the well is placed in the formation in the most permeable interlayer, and using filtering heterogeneity, they create pressure differentiation between the layers and their communication, thereby increasing the hydrodynamic connection between the low-permeable and high-permeability layers in thickness and the best reserves from all the layers.

Typically, formations of the greatest thickness are located between other formations suitable for development. In this case, if they have residual reserves of the late stage of reservoir development, perforation of existing wells in the reservoir in the interval of their occurrence and exposure to them through the existing well stock is possible.

The method is carried out in the following sequence.

A multilayer reservoir, represented by a heterogeneous reservoir, is drilled with a rare grid of wells, and an arrangement is carried out. The working agent is injected through injection wells into productive, cost-effective formations and formation fluid is taken through production wells. During operation, oil, water, injection and reservoir pressure are measured. Using the information obtained on newly drilled wells or on a drilled fund for production facilities, the geological structure of the reservoir, the distribution of the reservoir over the area and section of the reservoir, and the change in its filtration-capacitive properties are clarified. Maps of effective oil-saturated thicknesses are built, oil reserves are determined, and modeling of the reservoir development process is additionally carried out. Taking into account the current development conditions, sections of non-drained residual oil reserves in formations with different oil-saturated thicknesses are outlined in the oil zone. Horizontal and / or subhorizontal (possibly branched wells) are drilled so that their faces replace two or more design faces and are as close as possible to the approved grid density. When drilling wells, unstable tire rocks pass at an angle not exceeding the maximum penetration angle without collapse, casing the wellbore, overlapping unstable tire rocks, to the productive pack, the entire interval of heterogeneous productive pack rocks passes with a smaller bit diameter with a set angle of up to 90 ° to the sole, conduct oil saturation studies, select the formation with the largest residual reserves and thickness, then enter the selected formation with the next set of angles, go 90 °, pass the subhorizon layer flaxen and / or horizontally along the most permeable layer in it, do not leave the formation, controlling the drilling speed and gas indications by geological and technological studies (GTI), and in the presence of clay bridges and / or aquifers, the distance from the roof of the productive pack of the selected formation with residual reserves after oil saturation studies are cased with a shank and only oil-saturated formations are opened, each at two intersections, and the operation is subhorizontal and / or horizontal part of the wellbore in the selected formation is conducted through an open wellbore or filter with the descent of the shank of the tubing to the bottom of the wellbore.

At the same time, the filtration surface of the well in the pack and reservoir increases by a factor of one, allowing the introduction of non-drained reserves into development, to increase the coverage coefficient by their production and increase oil recovery. Depending on the cementation or rock strength composing the selected formation, the retrievable shank with the filter is lowered into the barrel or left open, providing impact over the entire profile of the formation. In the event of a drop in reservoir pressure of more than 0.2-0.3 MPa per year, injection wells from a previously drilled pool are being developed for injection. In the case of watering the well up to 98% translate it under injection.

Case Studies

Example 1

An oil reservoir with the following characteristics is being developed: depth 1820 m, reservoir temperature 28 ° C, reservoir pressure 17.6 MPa, porosity 16-26%, permeability 0.414 μm ² , oil saturation 84%, oil viscosity 7 MPa · s, oil density 889 kg / m ³ , the density of produced water is 1182 kg / m ³ . The deposit has been developed for 9 years.

Analyze the site of the deposit (Fig. 1) in the deposits of the Pashian horizon, where 1 is the vertical, 2 is the tubing, 3 is the operating string, 4 is the shoe, 5 is the liner, 6 is the open interval. The site has been drilled with a rare grid of wells; there is an arrangement. Water is injected into injection wells and formation fluid is produced through production wells. Measure oil production, water, injection and reservoir pressure. Based on the analysis of the drilled fund, the degree of depletion of the reserves is determined, residual oil-saturated thicknesses are determined from the reservoirs, residual oil-saturated thickness maps are constructed, oil, water-oil and water-flooded zones are separated, contour sections with residual oil reserves are delineated and horizontal wells are placed in the reservoir with the largest residual oil reserves and residual oil-saturated thick. The lower layer D1b3 is flooded. The D1b2 layer of small thickness has not been developed. Plast D1a is not developed.

The selected reservoir has the following characteristics: depth 1820 m, thickness 3.4 m, reservoir temperature 28 ° C, reservoir pressure 17.6 MPa, porosity 16-26%, permeability 0.414 μm ² , oil saturation 84%, oil viscosity 7 MPa · s , oil density 889 kg / m ³ , formation water density 1182 kg / m ³ , bottom: porosity 18%, permeability 0,092 μm ² , roof: porosity 16%, permeability 0,108 μm ² , in the middle part: porosity 27%, permeability of 0.583 μm ² .

One horizontal production well is drilled into a selected formation. Place the horizontal production wellbore in the allocated zone so that it ensures drainage of the undeveloped zone over the facility, but not more than the distance approved by the design grid design system. Oil reserves are calculated within the drainage zone of a horizontal well - 214.5 thousand tons of geological and 85.8 thousand tons of recoverable reserves. Core studies are carried out to determine the strength of the rocks of the tire, determine the maximum angle of penetration without obstruction (the maximum angle of penetration without obstruction is 64 °). A horizontal well is drilled with a chisel with a diameter of 215.9 mm, unstable rock formations pass at an angle of 60 °, not exceeding the maximum penetration angle without obstruction, casing the wellbore, blocking unstable rock formations, to a productive pack. A string of tubing with a diameter of 168 mm is lowered, installing its shoe in the roof of the productive bundle, the entire productive bundle is passed with a bit with a smaller diameter of 144 mm with a set angle of up to 90 ° to the sole, studies are being carried out, the lower formation D1b3 is partially flooded, the formation D1b2 is small in thickness not developed, reservoir D1b1 is replaced (not shown in Fig. 1), reservoir D1a of the greatest thickness has not been worked out, with the largest residual recoverable reserves of 73.8 thousand tons and a thickness of 3.4 m, the next set of angles enter the selected formation, determine the hypsometry eh about the soles, go 90 °, pass horizontally 170 m along the layer along the most permeable layer in it, do not go out of the layer, conducting control over geological and technological research (GTI). In the context of a productive pack according to geophysical studies (studies on oil saturation), the presence of clay bridges is determined. The distance from the roof of the productive pack to the selected reservoir with the largest residual reserves is planted with a 114 mm shank. The oil-saturated formation D1b2 of smaller thickness at the two intersections is revealed. The horizontal trunk is left open within the formation, as the sandstone is well cemented. The shank of the tubing is lowered to the lowest point of the well, determined according to the inclinometer, and the well is mastered. They put the well into operation. The oil production rate of the well is 2.4 times higher than that of the surrounding wells that opened the reservoir of the same thickness and amounts to 18.5 tons / day of anhydrous oil. According to the calculation, over 10 years of well operation, a total of 64.4 thousand tons of oil and 3.5 thousand tons of water will be produced. Watering is not observed. All extracted oil can be attributed to additional production, since under the existing development system, reserves in the interwell space could remain undeveloped.

An undeveloped section of the interwell space has been identified, unfilled reservoirs have been identified, and drainage has been ensured. Oil recovery over 10 years of operation in the considered area by the proposed method is 34.9%. At a cost of oil production of 5.3 thousand rubles. per ton and price of oil 10.5 thousand rubles. per ton, savings in sales on the domestic market will be:

E = ΔQn · (C-C) = 64.4 · 5.2 = 334.9 million rubles.,

where ΔQн - additional oil production, thousand tons,

C - the price of oil, thousand rubles / t,

C - the cost of production of one ton of oil, thousand rubles / t, i.e. according to the proposed method, an average of 6.4 thousand tons of additional oil will be produced per year and the savings for 1 year will be 33.5 million rubles.

By the end of the 37 year of operation, the production of the well was flooded to 98%, the reservoir pressure in the reservoir, despite the commissioning of two injection wells, continued to fall and the horizontal well was mastered for injection.

Example 2

An oil reservoir with the following characteristics is being developed: depth 1820 m, reservoir temperature 28 ° C, reservoir pressure 17.6 MPa, porosity 16-26%, permeability 0.414 μm ² , oil saturation 84%, oil viscosity 7 MPa · s, oil density 889 kg / m ³ , the density of produced water is 1182 kg / m ³ . The deposit has been developed for 8 years.

Analyze the site of the deposit (figure 2) in the deposits of the Pashian horizon, where 1 is the vertical, 2 is the tubing, 3 is the operating string, 4 is the shoe, 5 is the liner, 6 is the open interval. The site has been drilled with a rare grid of wells; there is an arrangement. Water is injected into injection wells and formation fluid is produced through production wells. Measure oil production, water, injection and reservoir pressure. Based on the analysis of the drilled fund, the degree of depletion of the reserves is determined, residual oil-saturated thicknesses are determined from the reservoirs, residual oil-saturated thickness maps are constructed, oil, water-oil and water-flooded zones are separated, contour sections with residual oil reserves are delineated and horizontal wells are placed in the reservoir with the largest residual oil reserves and residual oil-saturated thick. The lower layer D1b3 is flooded. The D1b2 layer of small thickness has not been developed. Plast D1a is not developed.

One horizontal production well is drilled into a selected formation. Oil reserves are calculated within the drainage zone of a horizontal well - 217.5 thousand tons of geological and 87 thousand tons of recoverable reserves. Core studies are carried out to determine the strength of the tire rocks, determine the maximum angle of penetration without obstruction (the maximum angle of penetration without obstruction is 62 °). A horizontal well is drilled with a chisel with a diameter of 215.9 mm, unstable rock formations pass at an angle of 60 °, not exceeding the maximum penetration angle without obstruction, casing the wellbore, blocking unstable rock formations, to a productive pack. A string of tubing with a diameter of 168 mm is lowered, installing its shoe in the roofing part of the productive pack, the entire productive pack is passed with a bit with a smaller diameter of 144 mm with a set angle of up to 90 ° to the sole, studies are being carried out, the lower formation D1b3 is partially waterflood, the formation D1b2 is small in thickness not developed, reservoir D1b1 is replaced (not shown in Fig. 2), reservoir D1a of the greatest thickness has not been developed, with the largest residual recoverable reserves of 74.3 thousand tons and a thickness of 3.7 m, the next set of angles enter the selected formation, determine the hypsometry eh about the soles, go 90 °, pass the formation subhorizontal 172 m along the most permeable layer in it, do not go out of the formation, conducting control over geological and technological research (GTI). In the context of a productive pack according to geophysical studies for oil saturation, the presence of clay bridges and aquifers was determined. The distance from the roof of the productive pack to the selected reservoir with the largest residual reserves is planted with a 114 mm shank. The oil-saturated interlayers of lesser thickness at the two reservoir intersections identified below by studies are opened. The subhorizontal trunk is left open within the formation, as the sandstone is well cemented. The shank of the tubing is lowered to the lowest point of the well, determined according to the inclinometer, and the well is mastered. They put the well into operation.

Example 3

Develop an oil reservoir. Analyze the site of the deposit (Fig. 3) in the deposits of the Pashian horizon, where 1 is the vertical, 2 is the tubing, 3 is the operating string, 4 is the shoe, 5 is the liner, 6 is the open interval. The site has been drilled with a rare grid of wells; there is an arrangement. Water is injected into injection wells and formation fluid is produced through production wells. Measure oil production, water, injection and reservoir pressure. Maps of residual oil-saturated thicknesses are built, oil, water-oil and water-flooded zones are separated, areas with residual oil reserves are outlined and horizontal wells are placed in the formation with the largest residual oil reserves and residual oil-saturated thickness. The lower layer D1b3 is flooded. The D1b2 layer of small thickness has not been developed. Plast D1a is not developed.

One production well with two faces is drilled into the selected formation. Oil reserves are calculated within the drainage zone of a horizontal well - 224.5 thousand tons of geological and 89.8 thousand tons of recoverable reserves. Core studies are carried out to determine the strength of the tire rocks, determine the maximum angle of penetration without obstruction (the maximum angle of penetration without obstruction is 62 °). A horizontal well is drilled with a chisel with a diameter of 215.9 mm, unstable rock formations pass at an angle of 60 °, not exceeding the maximum penetration angle without obstruction, casing the wellbore, blocking unstable rock formations, to a productive pack. A string of tubing with a diameter of 168 mm is lowered, installing its shoe in the roofing part of the productive pack, the entire productive pack is passed with a bit with a smaller diameter of 144 mm with a set angle of up to 90 ° to the sole, studies are being carried out, the lower formation D1b3 is partially waterflood, the formation D1b2 is small in thickness not developed, reservoir D1b1 is replaced (not shown in Fig. 3), reservoir D1a of the greatest thickness has not been worked out, with the largest residual recoverable reserves of 80.8 thousand tons and a thickness of 4.7 m, the next set of angles enter the selected formation, determine the hypsometry eh about the soles, go 90 °, pass horizontally 170 m along the most permeable layer in it, do not go out of the formation, monitoring the geological and technological research (GTI) a meter from the point of entry into the reservoir, cut and drill the second trunk subhorizontal bit 102 mm, 150 m of the trunk. In the context of a productive pack according to geophysical studies on oil saturation, the presence of aquifers was determined. The distance from the roof of the productive pack to the selected reservoir with the largest residual reserves is planted with a 114 mm shank. The oil-saturated formation D1b2 of smaller thickness at the two intersections is revealed. Horizontal and subhorizontal trunks are left open within the reservoir, as the sandstone is well cemented. The shank of the tubing is lowered to the lowest point of the well, determined according to the inclinometer, and the well is mastered. They put the well into operation.

The application of the proposed method will improve oil recovery in a multilayer oil reservoir in the late stage with unstable rocks of the tire and a heterogeneous reservoir.

Claims (1)

A method of developing a multilayer oil reservoir in the late stage with unstable rock formations and an inhomogeneous reservoir, including at least one well being driven along a section of a productive pack to the bottom with subsequent exit to the formation, lowering the tubing string to the lowest point of the trunk, operation wells, characterized in that the unstable tires of the tire pass at an angle not exceeding the maximum penetration angle without collapse, the well is cased, the unstable rocks of the tire are covered to the productive pack, the entire interval of heterogeneous rocks of the productive pack is covered with a smaller bit diameter with a set angle of up to 90 ° to the bottom of the pack, oil saturation studies are carried out, a formation with the largest residual oil reserves and oil-saturated thickness is selected, the next set of angles enter the selected formation, go to 90 °, pass along the formation subhorizontal and / or horizontally, along the most permeable layer, do not exit the formation, and in the presence of clay bridges and / or aquifers, the distance from the roof After conducting oil saturation studies, the productive packs of the selected reservoir with residual reserves are cased with a shank and only oil-saturated reservoirs are opened, each at two intersections, and the subhorizontal and / or horizontal parts of the wellbore are operated through an open trunk or filter with the pump shank compressor pipes to the bottom of the wellbore.

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