RU2286445C1 - Method for highly-viscous oil or bitumen deposit development - Google Patents

Abstract

FIELD: oil industry, particularly oil production stimulation with the use of heat.

SUBSTANCE: method involves drilling horizontal wells along with forming horizontal injection wells over producing horizontal wells; injecting heat-carrier agent through horizontal injection wells and producing formation fluid through horizontal producing wells. Deposit having carbonate reservoir is selected for development. Horizontal producing wells are transversal to natural carbonate reservoir rift direction. Horizontal injection wells are drilled from vertical wells to be arranged over horizontal producing well bores. Horizontal injection well bores are drilled by rock erosion under fluid pressure so that thin channels having diameters of 30-70 mm are created. The thin channels have different lengths so that channels having greater lengths are located in direction substantially transversal to natural carbonate reservoir rift direction. Thin channels having lesser lengths mainly extend in natural carbonate reservoir rift direction.

EFFECT: increased oil recovery.

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Description

The invention relates to the oil industry and may find application in the development of deposits of high viscosity oil or bitumen.

There is a method of developing an oil field with heterogeneous reservoirs, including drilling vertical production and injection wells, oil selection through production wells, pumping a working agent through injection wells, identifying low-permeability zones of the reservoir, drilling horizontal lateral shafts into low-permeability zones of the reservoir at low pressure in the well by erosion of the mountain rocks under high fluid pressure with the formation of thin and long channels, injection of the working agent into low-permeability zones cut lateral horizontal trunks with oil displacement into highly permeable zones. At the same time, the pressure in the well is reduced when drilling sidetracks by 5-10% of hydrostatic pressure. The rocks are washed out under a pressure of 15-20 MPa through a flexible pipe that is fed through a cut out side window (RF Patent No. 2256068, class E 21 B 43/16, publ. 10.07.2005).

The known method is suitable for the development of deposits of low viscosity oil, and for use in deposits of high viscosity oil or bitumen requires significant improvement.

A known method of thermal exposure to a reservoir of high viscosity oil, consisting of the following. Drill rows of vertical injection and production wells. Horizontal rows are drilled along rows of vertical wells. A coolant, such as steam, is periodically pumped into horizontal wells. Oil is taken from vertical producing and vertical injection wells. During the termination of steam injection, oil is taken from horizontal wells, which are a source of steam breakthrough into vertical wells. After the development of the formation in the area of the bottom-hole zones of all wells, they transfer to areal injection of a displacing agent, for example water, into vertical injection wells. At the same time, oil is taken from the remaining wells. Before the areal injection of the displacing agent, horizontal wells located near the vertical injection wells are filled with an insulating composition, for example, a gel-forming one (RF Patent No. 2199656, class E 21 B 43/24, publ. 02.27.2003).

The known method is complicated, involves the presence of expensive horizontal wells. The development of deposits by this method is accompanied by breakthroughs of water to producing wells and, as a result, low oil recovery.

Closest to the proposed invention in technical essence is a method of developing deposits of high viscosity oils and bitumen using heat in combination with inclined horizontal wells. The method includes drilling wells on a specific grid, injecting a displacing agent through injection wells and selecting formation fluids through production wells. Well drilling is carried out on a radial grid. Injection wells are located on the reservoir closer to the upper boundary of the reservoir along the most permeable layers. Production wells are located closer to the lower boundary of the reservoir. At the initial stage of development, all wells conduct thermocyclic treatment of the formation with steam stimulation. Subsequently, they switch to the selection of reservoir fluids through production wells with areal exposure to the reservoir through injection wells (RF Patent No. 2237804, class E 21 B 43/24, publ. 10.10.2004 - prototype).

The known method does not provide the necessary coverage of the reservoir by thermal exposure, as a result of which oil recovery remains at a low level.

The proposed method solves the problem of increasing oil recovery deposits.

The problem is solved in that in the method for developing a highly viscous oil or bitumen deposit, comprising drilling horizontal wells with horizontal injection wells above producing horizontal wells, pumping coolant through horizontal horizontal wells and selecting reservoir fluids through horizontal producing wells, according to the invention, a reservoir with carbonate reservoir, producing horizontal wells are placed perpendicular to the direction of the natural fracture a carbonate reservoir, and horizontal injection wells are drilled from vertical wells located above horizontal wells of production wells, and horizontal wells of injection wells are drilled by erosion of the rock under fluid pressure with the formation of thin and long channels, while thin and long channels perform different lengths with predominant by placing longer channels in a direction close to the direction perpendicular to the direction of the natural fracture of the carbonate reservoir torus, and shorter channels are predominantly placed in the direction of natural fracturing of the carbonate reservoir.

The features of the invention are:

1. drilling horizontal wells with the placement of injection horizontal wells above producing horizontal wells;

2. coolant injection through horizontal injection wells;

3. the selection of reservoir fluids through producing horizontal wells;

4. the choice for the development of deposits with a carbonate reservoir;

5. placement of producing horizontal wells perpendicular to the direction of natural fracture of the carbonate reservoir;

6. drilling horizontal injection wells from vertical wells located above horizontal trunks of production wells;

7. drilling horizontal wells of injection wells by erosion of the rock under fluid pressure with the formation of thin and long channels;

8. the implementation of thin and long channels of different lengths;

9. preferential placement of longer channels in a direction close to the direction perpendicular to the direction of natural fracturing of the carbonate reservoir;

10. preferential placement of shorter channels in the direction of natural fracturing of the carbonate reservoir.

Signs 1-3 are common with the prototype, signs 4-10 are the salient features of the invention.

SUMMARY OF THE INVENTION

The reservoir rocks of highly viscous oil or bitumen deposits are often represented by non-cemented and weakly cemented sandstones. So, in the Mordovo-Kamalsky and Ashalchinsky bitumen deposits, the fastening substance for such rocks is bitumen itself, whose viscosity at a reservoir temperature of 8 ° C is 15-20 thousand centipoise (MPa · s). Cores taken from the reservoir and warmed to room temperature scatter. In such conditions, the use of open-hole wells is impossible. At the same time, the use of open-hole trunks in carbonate deposits having a strong skeleton is very promising and can lead to a significant increase in the coverage of the formation by impact and an increase in the oil recovery of the reservoir.

The proposed method solves the problem of increasing oil recovery deposits with carbonate reservoir.

The problem is solved as follows.

When developing a reservoir of high-viscosity oil or bitumen with a carbonate reservoir, at least one production well with a horizontal wellbore is perpendicular to the direction of natural fracture of the carbonate reservoir, preferably along the bottom of the reservoir. Vertical injection wells are drilled above the horizontal trunk of the producing horizontal well. Vertical injection wells are cased and cemented. From vertical injection wells above the horizontal well of the producing horizontal well, horizontal channels are drilled by erosion of the rock under fluid pressure. In this case, the channels are made thin and long of different lengths with the placement of longer channels in the direction perpendicular to the direction of natural fracture of the carbonate reservoir, and shorter channels are placed in the direction of natural fracture of the carbonate reservoir. When placing the channels between the directions perpendicular and along the direction of natural fracture, channels of intermediate length are formed between longer and less long channels. Since the permeability of the formation in the direction of natural fracturing is greater than in the perpendicular direction, for uniform coverage of the formation by thermal action, it is necessary to make the channels along the direction of natural fracture short and in the perpendicular direction longer. In this case, we should expect uniform heating of the formation over the horizontal wellbore of the producing well. The reservoir pressure in the reservoir is practically absent. Under the influence of the coolant, high-viscosity oil or bitumen warms up, acquires fluidity and flows down to the producing well, from which it is taken to the surface.

It is preferable that the ratio of lengths along and across the direction of natural fracture is inversely proportional to the permeabilities along and across this direction.

In Fig.1 presents a plan of the development site of deposits of highly viscous oil or bitumen, Fig.2 - profile of the reservoir.

In the reservoir 1, perpendicular to the direction of natural fracturing 2, a horizontal wellbore 3 of a producing well is drilled, above which vertical injection wells 4 are drilled with horizontal channels along 5 and perpendicularly 6 to the direction of natural fracturing 2. Channels 5 and 6 extend above the horizontal wellbore 3 of the producing well. Vertical injection wells 4 are carried out next to the horizontal wellbore 3 or above the horizontal wellbore 3, without bringing the vertical wellbore 4 to the horizontal wellbore 3.

To form channels 5 and 6, the casing of a vertical well 4 is milled at a height of 4-6 m above the horizontal well 3 of the producing well, the jet nozzle is lowered on a high-pressure hose and a flexible pipe, fluid is pumped under a pressure of 15-20 MPa with a flow rate of 1-2 l / s and conduct radial opening with the formation of channels 5 and 6 with a diameter of 30-70 mm The fluid used is an aqueous solution of polymer Pac-R with a concentration of 0.2 kg per 1.5 m ^{3 of} water with the addition of 2-3% potassium chloride. After the formation of channels 5 and 6, 180-200 liters of a 10-15% hydrochloric acid solution are pumped into them.

Fluid, such as steam, steam-water mixture, etc., is pumped through vertical injection wells 4 and channels 5 and 6, and formation fluids are taken through a horizontal wellbore 3 of the producing well.

After depletion of reserves from the heating zone, i.e. basically between the horizontal wellbore 3 of the producing well and channels 5 and 6, in the vertical injection well 4 at a depth of 4-6 m higher than the existing channels 5 and 6, the same channels are made using the same technology. Thus, a new floor of heat exposure is organized through newly formed channels and formation fluid selection through the existing horizontal wellbore 3 of the producing well.

As a result, due to the wide coverage of the formation by thermal action, the oil recovery of the reservoir increases.

Concrete example

A highly viscous oil field is being developed at a depth of 90 m, represented by 20-30 m thick formations with a temperature of 8 ° C, a pressure of 0.5 MPa, an oil saturation of 0.70 units, a porosity of 30%, and a permeability of 0.265 μm ² , with oil having a density of 956 kg / m ³ and a viscosity of 12206 MPa · s.

In the reservoir 1, perpendicular to the direction of natural fracture 2, a horizontal well 3 of a producing well 400 m long is drilled. Vertical wells 4 with horizontal channels along 5 and perpendicularly 6 to the direction of natural fracture 2 are drilled above horizontal well 3 and channels 5 are 30-40 m long. Channels 6 are 100 m long. The diameter of channels 5 and 6 is 50 mm.

Steam is injected through vertical injection wells 4 and channels 5 and 6. Formation fluids are collected through a horizontal wellbore 3 of a producing well.

After depletion of reserves from the heating zone in the vertical injection well 4 at a depth of 4-6 m higher, the existing channels 5 and 6 use the same technology to perform the same channels. A new floor of heat exposure is organized through newly formed channels and formation fluid selection through the existing horizontal wellbore 3 of the producing well.

As a result, the coverage coefficient of the formation by impact was 0.7 instead of 0.4 for the prototype, and the displacement coefficient was 0.68 instead of 0.50 for the prototype.

The application of the proposed method will improve oil recovery deposits.

Claims (1)

A method of developing a reservoir of high viscosity oil or bitumen, including drilling horizontal wells with horizontal injection wells above producing horizontal wells, pumping coolant through horizontal horizontal wells and selecting reservoir fluids through horizontal producing wells, characterized in that a reservoir with a carbonate reservoir is selected for development horizontal wells are placed perpendicular to the direction of natural fracture of the carbonate reservoir and horizontal injection wells are drilled from vertical wells located above horizontal wells of production wells, and horizontal wells of injection wells are drilled by erosion of the rock under fluid pressure with the formation of thin and long channels with a diameter of 30-70 mm, while thin and long channels are of different lengths with the preferential placement of longer channels in a direction close to the direction perpendicular to the direction of natural fracture of the carbonate reservoir, and e long channels preferably arranged in the direction of natural fracturing a carbonate reservoir.

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