RU2065936C1 - Method of developing nonuniform oil pool - Google Patents

Abstract

FIELD: oil and gas production. SUBSTANCE: in the late stage of developing oil pool, a productive well is found, to which working medium from injection well comes with highest velocity. A polymer material solution is pumped in simultaneously through injection well and preset well. Volume of solution pumped through the latter is 15-25% that of solution volume pumped through the former. After polymer material solution is pumped in, the injection wells are pumped through with working medium, and crude oil is produced through productive wells. EFFECT: increased oil production.

Description

 The invention relates to the oil industry and may find application in the development of a heterogeneous oil reservoir.

A known method for the development of oil deposits, including the injection of a working agent through injection wells and the selection of oil through production wells [1]
The known method does not allow to develop an oil reservoir with high oil recovery due to the rapid flooding of mining products.

Closest to the invention in technical essence is a method of developing an oil reservoir, including the selection of oil through production wells and injection through injection wells of a working agent and a solution of polymer material [2]
The known method allows you to align the front of the injection of the working agent by reducing the permeability of highly permeable zones of the formation. However, this method is ineffective at the late stage of reservoir development, in the conditions of steady-state highly watered flows of reservoir fluids not only between individual wells, but even between separate zones of the reservoir. In this case, the injection of a solution of polymer material is often ineffective. As a result, the oil recovery of the reservoir remains at a low level.

 The aim of the invention is to increase oil recovery deposits.

 This is achieved by the fact that in the method for developing a heterogeneous reservoir, which includes taking oil through production wells and injecting a working agent and a solution of polymer material through injection wells, according to the invention, at a later stage of development, before injection of a solution of polymer material, a production well is determined which passes most rapidly working agent from an injection well; when injecting a solution of polymer material through an injection well, a polymer solution is simultaneously injected material through a previously defined production well in an amount equal to 15-25% of the injection solution of the polymeric material through the injection well.

 The essential features of the invention are: the selection of oil through production wells; injection of a working agent through injection wells; injection of a solution of polymer material through injection wells; conducting the process at a late stage of reservoir development; determining the production well to which the working agent passes from the injection well at the highest speed; injection of a solution of polymer material through a previously defined production well; injection of a solution of polymer material through a specific production well in a volume equal to 15-25% of the volume of injection of a solution of polymer material through an injection well.

 At a late stage of oil field development, with significant flooding of the produced products in the reservoir, large waterflood zones are formed. The injection of a solution of polymeric material through an injection well allows isolation of a highly permeable zone in the largest interval of the reservoir. However, in the presence of an injection front from a number of injection wells, as a rule, it is not possible to increase the permeability of highly permeable zones along the entire injection front. The effect of injecting a solution of a polymer material is not high due to the impossibility of isolating highly watered zones along the entire front. The solution to this problem is achieved to a large extent by simultaneously injecting a solution of polymer material simultaneously into injection wells of the injection row and into the production well, into which the working agent passes from the injection well to the producing well with the highest speed. In this case, the solution of the polymer material penetrates into the vast zone of high permeability and blocks the most productive zones of the flow of formation fluids. The ratio of the volumes of injection of the polymer material solution through the injection and through the production well is determined experimentally and allows the most efficient alignment of the displacement front.

 The highest velocity of the working agent from the injection well to the producing one is determined as follows: the radioactive element is pumped through the injection wells and the first producing well is detected in which the injected radioactive element is detected.

An oil field of 8 km long and 7 km wide is being developed. The deposit has the following characteristics: permeability of 0.4 D; porosity 0.2; reservoir thickness 5 m; formation depth 1700 m; reservoir temperature 37 ^o C; initial reservoir pressure of 17 MPa; the density of oil in reservoir conditions 0.846 g / cm ³ ; oil viscosity in reservoir conditions 15 cP; gas factor 16 m ³ / t, saturation pressure 3.3 MPa. The reservoir is terrigenous. After 40 injection wells, the working agent pumped the associated Devonian water into the reservoir, and oil was taken from the reservoir through 96 production wells. An oil reservoir is developed before flooding of the produced products 85-90%. A working agent with the radioactive isotope sodium-22 is pumped through 6 wells of the injection row and its appearance is recorded in the 12 nearest producing wells. It is determined that at first the radioactive isotope is seen in the producing well opposite the central part of a number of injection wells. A 0.1% aqueous solution of polyacrylamide is pumped through 6 wells of the injection row and through a specific production well. The injection volume through each injection well is 20,000 m ³ , through the producing well 4,000 m ^{3 of} solution. After technological exposure, the producing well is put into operation and the working agent is pumped through the injection well.

Example 2. Perform, as example 1, but as a solution of polymer material using a 0.11% solution of hydrolyzed polyacrylamide, the injection volume through each injection well is 20,000 m ³ , through the production well 5,000 m ^{3 of the} solution.

Example 3. Perform, as example 1, but the injection volume through each injection well is 20,000 m ³ , through the production well 3,000 m ^{3 of the} solution.

The application of the proposed method allows to reduce the water cut of produced products by 50%, while when injecting a solution of polymer material only through injection wells, the water cut of produced products in 12 producing wells decreased by 40%
The application of the proposed method allows to reduce the water content of the extracted products and increase oil recovery by 0.5-1.0%

Claims (1)

 A method for developing a heterogeneous oil reservoir, including oil extraction through production wells and pumping a working agent and a polymer material solution through injection wells, characterized in that, at a late stage of development, a production well is determined before the polymer material solution is injected, to which the working agent passes most rapidly from injection well, when injecting a solution of polymer material through an injection well, simultaneously injecting a solution of polymer material through anee specific producing well in a volume of 15 25% of a polymeric material injection solution through the injection well.