RU2334095C1 - Method of high-viscosity oil pool development - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method involves drilling vertical injection wells and horizontal producing wells, injection of working agent via injection wells and oil withdrawal via production wells. Horizontal hole of production well is arranged 1.5-2.5 m above the productive stratum bottom and is perforated. Bottom of vertical injection well is arranged 3.5-4.5 m above the horizontal hole of producing well and is perforated at 0.5-1.5 m interval from the bottom. The distance between vertical injection well and the vertical hole of producing well is longer than 2/3 of horizontal producing well length up to the end of horizontal hole. Working agent is steam alternating with air.

EFFECT: increased oil yield of a pool.

1 ex, 1 dwg

Description

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

A known method of developing deposits of high viscosity oil, according to which 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, publ. 2003.02.27).

The known method allows you to cover the impact of a large area of the reservoir, however, while in the interwell space remain undeveloped zone.

Closest to the proposed invention in technical essence is a method of developing a reservoir of high viscosity oil, according to which vertical injection and horizontal and vertical wells are drilled on a reservoir of high viscosity oil. The coolant is pumped through the injection wells and at the same time periodically through horizontal wells until the coolant breaks through to the vertical production wells. After the coolant breakthrough, a displacing agent is pumped through the injection wells, and sand and formation fluid are selected through horizontal wells (RF Patent No. 2062865, publ. 1996.06.27 - prototype).

The known method does not allow to develop an oil reservoir with the achievement of high oil recovery.

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

The problem is solved in that in the method of developing a highly viscous oil deposit, including drilling vertical injection wells and horizontal production wells, pumping a working agent through injection wells and selecting oil through production wells, according to the invention, the horizontal well of the producing well is carried out in 1.5-2, 5 m above the bottom of the reservoir, the horizontal well is perforated, the bottom of the vertical injection well, perforated, is placed 3.5-4.5 m above the horizontal well of the producing well in the range of 0.5-1.5 m from the bottom, the vertical injection well is placed from the vertical wellbore at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal well, while steam is used as a working agent alternating with air.

The features of the invention are:

1. drilling vertical injection wells;

2. drilling of horizontal producing wells;

3. pumping a working agent through injection wells;

4. selection of oil through production wells;

5. Posting a horizontal wellbore of a producing well 1.5-2.5 m above the bottom of the reservoir;

6. perforation of the horizontal barrel;

7. Above the horizontal wellbore of the producing well by 3.5-4.5 m, the placement of the bottom of the vertical injection well;

8. perforation of a vertical injection well in the range of 0.5-1.5 m from the bottom;

9. placement of a vertical injection well from a vertical wellbore of a producing well at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal wellbore;

10. the use of steam as a working agent in alternation with air.

Signs 1-4 are common with the prototype, signs 5-10 are the salient features of the invention.

SUMMARY OF THE INVENTION

When developing a highly viscous oil deposit (with a viscosity of more than 300 mPa · s), especially in terrigenous reservoirs of small (8 to 30 m) thickness, as a rule, the oil recovery of the reservoir remains low even when using horizontal wells. This is due to the irrational ratio of the lengths of the horizontal sections of the wells and the distances to the injection wells. At the same time, a significant part of the oil reserves is buried in the reservoir. Oil recovery remains low. The proposed invention solves the problem of increasing oil recovery deposits. The problem is solved as follows.

When developing high-viscosity oil deposits, vertical injection wells and horizontal production wells are drilled. The drawing shows a layout of wells. Steam is pumped in alternation with air through vertical injection wells 1, oil is withdrawn through horizontal production wells having a vertical 2 and a horizontal wellbore 3. A horizontal wellbore of a production well 3 of length L is carried out at a distance of 1.5- above the sole 4 of the productive formation 5 2.5 m, and perforated 6. Above the horizontal well of the producing well 3 at a distance L equal to 3.5-4.5 m, place the bottom of the vertical injection well 1, perforated in the interval from 0.5-1.5 m from the bottom. The vertical injection well 1 is placed from the vertical wellbore of the producing well 2 at a distance d greater than 2/3 of the length L of the horizontal wellbore 3 of the producing well, up to the end of the horizontal well 3. The steam is injected until a deposit zone is developed near the injection well 1, as evidenced by the sharp reduction in production flow rate. After that, air is pumped, which occupies the upper part of the reservoir, forcing oil down. Then steam is injected again, which heats the formation. Heated oil flows down to the producing well.

Concrete example

A highly viscous oil reservoir is developed with the following characteristics: depth 90 m, reservoir thickness 8-30 m, reservoir temperature 8 ° C, reservoir pressure 0.5 MPa, oil saturation 0.70 ged units, porosity 30%, permeability 0.265 μm ² , oil density 956 kg / m ³ , viscosity 500 mPa · s.

When developing high-viscosity oil deposits, vertical injection wells and horizontal production wells are drilled according to the drawing. Steam is pumped in alternation with air through vertical injection wells 1, oil is withdrawn through horizontal production wells having a vertical 2 and a horizontal well 3 of 200 m length. The horizontal well of the producing well 3 is carried out 2 m above the sole 4 of the producing formation 5 and is perforated 6. Above horizontal of the producing wellbore 3 by 4 m, the bottom of the vertical injection well 1, perforated 6 in the range of 1 m from the bottom, is placed. The vertical injection well 1 is placed from the vertical wellbore of the producing well 2 at a distance greater than 2/3 of the length of the horizontal wellbore 3 of the producing well, i.e. at a distance of 140 m.

As a result, it is possible to achieve oil recovery of a deposit of 50%, while known methods can achieve oil recovery of the order of 25-30%.

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

Claims (1)

A method for developing a highly viscous oil deposit, including drilling vertical injection wells and horizontal production wells, injecting a working agent through injection wells and taking oil through production wells, characterized in that the horizontal well of the producing well is carried out at 1.5-2.5 m above the bottom of the productive formation, the horizontal well is perforated, the bottom of the vertical injection well, perforated in the range of 0.5-1.5 m from the bottom, is placed 3.5-4.5 m above the horizontal well of the producing well rtikalnuyu injection well placed on the vertical stem of the production well at a distance greater than 2/3 the length of the horizontal section of the production well until the end of the horizontal wellbore, at the same time as the working agent vapor is used in alternation with air.