RU2334086C1 - Method of oil pool development - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method involves injection of working agent via injection wells in cyclic mode, injection of periodic polymer injection of, and withdrawal of oil via production wells. Injection wells are positioned in a closed cluster pattern, inside of which production wells are located. Polymer solution is injected to injection wells in three stages. At the first stage, polymer solution is injected in turns via one injection well. At the second stage, polymer solution is injected in turns into all injection wells along the site perimetre, so that the injection wells omitted at the first stage receive the same polymer solution volume as at the first stage, while the injection wells filled at the first stage receive multiply lesser polymer solution volume than at the first stage. At the third stage, polymer solution is injected selectively to induction wells along the site perimetre in multiply lesser volume than at the first stage. Between the injections the injection wells operate without polymer solution injection.

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 oil deposits by cyclic flooding.

A known method of developing a heterogeneous oil field, including the injection through the injection wells of the working agent in a cyclic mode, the periodic injection of a polymer solution and the selection of oil through production wells. In the initial period, the polymer solution with the maximum concentration is pumped at a pressure that ensures the injectivity of highly productive wells, then the polymer solution with a lower concentration is pumped at the working injection pressures, while during the idle time of the injection wells through the production wells with a high rate of water cut rise, the produced products are forcedly selected (Number Document: 98103528/03, published. 1999.03.10).

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

Closest to the proposed invention in technical essence is a method for developing heterogeneous reservoirs during cyclic flooding, including cyclically lowering and increasing the pressure in the reservoir by pumping water through injection wells, injecting an aqueous polymer solution and taking oil from production wells. Additionally pumped a suspension of dispersed particles, and the injection of an aqueous polymer solution is carried out in alternating mode with a suspension of dispersed particles (RF Patent No. 2078917, published. 1997.05.10 - prototype).

The known method allows you to select oil from low-permeability zones of the reservoir, however, oil recovery remains at a low level.

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

The problem is solved in that in a method for developing an oil reservoir, comprising injecting a working agent through injection wells in a cyclic mode, periodically injecting a polymer solution and extracting oil through production wells, according to the invention, injection wells are placed in a block-closed system inside which production wells are placed, polymer solution is injected into injection wells in three stages; at the first stage, polymer solution is injected alternately through one injection well, the second stage, the polymer solution is injected into all injection wells along the perimeter of the site, and in the injection wells, into which the polymer solution was not injected in the first stage, they are pumped in the same volume as in the first stage, and into the injection wells into which polymer solution injection at the first stage, polymer solution is injected in a volume that is a multiple of the injection volume at the first stage; at the third stage, the polymer solution is sampled into injection wells by erimetru portion in an amount less than a multiple of the volume of injection at the first stage, wherein between periods of work performed uploads injection wells without pumping the polymer solution.

The features of the invention are:

1) injection through the injection wells of the working agent in a cyclic mode;

2) periodic injection of a polymer solution;

3) oil extraction through production wells;

4) placement of injection wells in a block-closed system, inside which production wells are placed;

5) injection of polymer solution into injection wells in three stages;

6) at the first stage, the injection of the polymer solution alternately through one injection well;

7) at the second stage, the injection of the polymer solution in turn into all injection wells around the perimeter of the site;

8) moreover, in injection wells, into which injection was not performed in the first stage, the polymer solution is injected in the same volume as in the first stage, and in injection wells, into which the polymer solution was injected, in the first stage, the polymer solution is injected in volume , a multiple of the smaller download volume in the first stage;

9) at the third stage, the implementation of selective injection of the polymer solution into the injection wells along the perimeter of the site in a volume that is multiple less than the injection volume at the first stage;

10) between the injections, the periods of operation of the injection wells are performed without injection of the polymer solution.

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

SUMMARY OF THE INVENTION

When developing an oil reservoir, cyclic flooding and periodic injection of polymer solutions are used to displace oil from low-permeability zones. At the same time, it is possible to extract additional oil, however, a significant part of the recoverable reserves remains in the reservoir. The proposed invention solves the problem of increasing oil recovery deposits. The problem is solved as follows.

When developing an oil field, injection wells are placed in a block-closed system, inside which production wells are placed. The polymer solution is injected into injection wells in three stages. At the first stage, the polymer solution is injected into the injection wells along the perimeter of the site alternately through one injection well with the injection of the polymer solution into each well in a volume of 150-500 m ³ . Thus, at the first stage, half of the injection wells remain without injection of the polymer solution. At the second stage of work, the polymer solution is pumped into all injection wells along the perimeter of the site in turn, and with the same volume of polymer solution injected in the volume of 150-500 m ³ into wells into which they were not injected at the first stage, and into wells into which the polymer solution was pumped at the first stage, the polymer solution was pumped in a volume that was a multiple of the main volume (15-50 m ³ ). At the third stage, the polymer solution is sampled into injection wells with increased injectivity along the perimeter of the site in a volume that is multiple less than the main volume (15-50 m ³ ). The time gap between the injection of the polymer solution into each subsequent well is 2-3 months.

Before injection, the polymer is dissolved in fresh water to a concentration of 0.1-0.5%. As the polymer, water-soluble polymers such as polyacrylamide, hydrolyzed polyacrylonitrile and the like are used.

Concrete example

An oil reservoir with the following characteristics is being developed: a reservoir-vault type deposit with a partial lithological restriction, the oil floor is 6 m, the depth of the formation roof is 990-1020 m, effective oil-saturated thicknesses vary from 1.7 m to 6.0 m. The reservoir rocks are porous-permeable and fractured limestones, to varying degrees, clay and dolomitic; porosity 15%, permeability 0.115 μm ² , average oil saturated thickness 3.5 m, oil viscosity 123.3 mPa · s, oil saturation 72%, reservoir oil density 0.904 g / cm ³ , gas content 7 m ³ / t.

The drawing shows a plot of oil deposits, which is developed by 20 producing (1) and 18 injection wells (2). The well placement system is block-closed with 5 injection wells in the same rows and 4 injection wells in the perpendicular rows. Inside the block, producing wells are placed. The injection of the working agent - wastewater is carried out in a cyclic mode with a period of 15 days.

The polymer solution is injected into injection wells along the perimeter of the site alternately through one well in a volume of 300 m ³ . After the completion of the first stage of work, the polymer solution is pumped into all injection wells along the perimeter of the site in turn, with the same volume of polymer solution injection of 300 m ³ into the wells into which they were not pumped at the first stage, and into the wells into which they were pumped polymer solution in the first stage, the polymer solution is injected in a volume equal to 30 m ³ . At the third stage of work, selective polymer solution is injected into injection wells with increased injectivity along the perimeter of the site in a volume of 30 m ³ . The time gap between the injection of the polymer solution into each subsequent well is 2 months.

As a result, the oil recovery of the deposit area increased by 3% and amounted to 35%, while the prototype in similar conditions, oil recovery did not exceed 33%.

The application of the proposed method will solve the problem of increasing oil recovery deposits.

Claims (1)

A method of developing an oil deposit, including pumping through the injection wells of a working agent in a cyclic mode, periodically pumping a polymer solution and taking oil through production wells, characterized in that the injection wells are placed in a block-closed system, inside which production wells are placed, the polymer solution is injected into injection wells are carried out in three stages; at the first stage, the polymer solution is injected alternately through one injection well; at the second stage, the injection of solution Polymers of polymer are produced alternately in all injection wells along the perimeter of the site, and in injection wells, into which injection was not performed in the first stage, the polymer solution is pumped in the same volume as in the first stage, and in injection wells into which the solution was injected polymer at the first stage, the polymer solution is injected in a volume that is a multiple of the injection volume at the first stage, and at the third stage, the polymer solution is sampled into injection wells along the perimeter of the section in , a multiple of the smaller injection volume in the first stage, while between the injections, the periods of operation of the injection wells without injection of the polymer solution are performed.