RU2594185C1 - Method for development of non-homogeneous oil deposit - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to oil industry and can be used in developing oil deposit with inhomogeneous permeability beds. Method for development of inhomogeneous oil deposit, which involves separation of deposit into zones with high, medium and low permeability, pumping through injection wells of displacement agents with different viscosity in different zones and recovery of formation products through production wells, in zone with low permeability to 100 mD displacement agent is pumped with viscosity equal to viscosity of formation water cyclically with periodicity of 15 days, in zone with average permeability of header from 100 to 500 mD displacement agent is pumped with viscosity higher than viscosity of displacement agent pumped into zone with low permeability at 40 % cyclically with periodicity of 12 days, in zone with high permeability reservoir more than 500 mD displacement agent is pumped with viscosity higher than viscosity of displacement agent pumped into zone with medium permeability at 50 % cyclically with periodicity of 9 days.

EFFECT: high uniformity of production areas.

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Description

The invention relates to the field of the oil industry and may find application in the development of an oil field with heterogeneous permeability formations.

A known method for the development of heterogeneous permeability of oil reservoirs, which consists in injecting into the reservoir a water solution of an polymer of high viscosity [M.L. Surguchev "Secondary and tertiary methods of increasing oil recovery". M .: Nedra, 1985, pp. 165-175].

In this case, at the displacement front, the viscosity instability decreases, and when pumped through a single filter, the rim volume is distributed over the interlayers in proportion to their injectivity. A larger volume penetrates into highly permeable layers and increases their filtration resistance to a greater extent, which ultimately is believed to lead to a leveling out of the displacement front and an increase in the coverage of the formation by water flooding. Based on the experimental data, the optimal rim volume is considered to be within 0.2-0.3 of the pore volume of the formation at a polymer weight concentration of 0.05%.

The disadvantage of this method is often premature breakthrough of water through a highly permeable interlayer, when the viscosity characteristics of the solution and the resistance factor become insufficient.

This is eliminated in the method of developing heterogeneous permeability of oil reservoirs with high permeability layers, which consists in pumping an aqueous polymer solution into the formation with the addition of a thickener [A.S. USSR 1837104, publ. 08/30/1993]. This method helps to prevent premature breakthrough of injected water in highly permeable layers.

The disadvantage of these methods is that viscous polymer solutions substantially block low-permeability layers.

Closest to the proposed invention in technical essence is a method of developing heterogeneous permeability of oil reservoirs, which consists in simultaneous-separate injection through injection wells of the rims of polymer solutions, followed by pushing them with water. In this case, solutions of high molecular weight polymers are pumped into highly permeable interlayers, and solutions of low molecular weight polymers are injected into low-permeable interlayers, provided that the average size of the polymer macromolecules injected into the interlayers is smaller than the average diameter of the pore channels [RF patent No. 2095555, publ. November 10, 1997 - prototype].

The disadvantage of the prototype is that the injection of a polymer solution of even a small molecular weight into low permeable layers reduces the rate of oil production from the layer, thereby reducing the overall rate of production.

The need to align the front of the displacement in the reservoir requires an increase in the viscosity characteristics of the solution for highly permeable layers. This leads to an increase in reagent consumption, and the pace of development is reduced. All this leads to uneven development of individual zones of the reservoir.

In the proposed invention solves the problem of increasing the uniformity of the development of zones of deposits.

The problem is solved in that in a method for developing a heterogeneous oil reservoir, comprising dividing the reservoir into zones of high, medium and low permeability, injecting displacing agents with different viscosities with different viscosities into different zones and injecting reservoir products through production wells, according to the invention, into a zone with a low permeability of up to 100 mD, a displacing agent with a viscosity of equal viscosity of produced water is pumped cyclically with a periodicity of 15 days into the zone with an average reservoir permeability of 100 to 500 mD of injection a displacing agent with a viscosity higher than the viscosity of the displacing agent injected into the zone with low permeability is 40% cyclic with a periodicity of 12 days, a displacing agent with a viscosity higher than the viscosity of the displacing agent being injected is pumped into the zone with a high permeability of a collector of more than 500 md in the zone with medium permeability, 50% cyclically with a frequency of 9 days.

SUMMARY OF THE INVENTION

When developing a heterogeneous oil reservoir, different sections of the reservoir with different permeabilities are developed unevenly, which entails significant material costs for maintaining the operation of the partially developed reservoir. In the proposed invention solves the problem of increasing the uniformity of the development of zones of deposits. The problem is solved as follows.

When developing a heterogeneous oil reservoir, the reservoir is divided into zones with high permeability of more than 500 mD, average permeability of 100 to 500 mD and low permeability of up to 100 mD. At the initial identical values of oil viscosity and reservoir pressure, a displacing agent with different viscosity is injected throughout the reservoir in the selected zones: into the zone with low permeability of the reservoir up to 100 mD — with a viscosity of the displacing agent of equal viscosity of produced water, and the injection is carried out cyclically with a periodicity of 15 days , allowing the displacing agent to be uniformly distributed over the cracks, cavities and pores of the matrix. A displacing agent with a viscosity higher than the viscosity of the displacing agent injected into the low-permeability zone by 40% is injected into the zone with an average permeability of the collector from 100 to 500 mD, by cycling the injection with a period of 12 days to allow technological exposure, which will equalize the front oil displacement. A displacing agent with a viscosity higher than the viscosity of the displacing agent injected into the zone with an average permeability of 50% is pumped into a zone with a high permeability of a reservoir of more than 500 mD, by cycling the injection with a period of 9 days, allowing the displacing agent to achieve the maximum reduction in the fluid velocity the most permeable interlayers.

Concrete example

An oil reservoir with the following characteristics is being developed: depth 1090 m, reservoir temperature 25 ° C, reservoir pressure 11 MPa, average porosity 28%, average permeability 1.7 μm ² , oil viscosity at reservoir conditions 58 MPa · s, oil density 0.888 t / m ³ . The collector is porous. The reservoir layer is arch.

The deposit is being developed by flooding. The working agent is pumped - produced water through injection wells, and reservoir products are taken through production wells.

The deposit is divided into zones with a high permeability of more than 500 mD, an average permeability of 100 to 500 mD, and a low permeability of up to 100 mD.

A displacement agent with a viscosity equal to the viscosity of formation water is pumped into a zone with a low permeability of a reservoir of up to 100 mD. with a viscosity of 1.6 MPa * s, moreover, the injection is carried out cyclically with a frequency of 15 days - injection, 15 days - stop. To thicken the water using a water-soluble polymer - polyacrylamide (PAA). As a displacing agent, a 0.001-0.002% aqueous PAA solution is used. In this case, PAA is used in the form of an 8% concentration according to TU 6-02-00209912-61-97.

A displacing agent with a viscosity higher than 40% is injected into a zone with an average collector permeability of 100 to 500 mD, which is 40% higher than the viscosity of a displacing agent injected into a zone with a low permeability. 2.24 MPa * s, and the injection is carried out with a period of 12 days - injection, 12 days - stop. As a displacing agent, a 0.003-0.004% PAA solution is used. PAA is used in the form of an 8% concentration according to TU 6-02-00209912-61-97 or granular sulfate under the name PAA-GS according to TU 2216-001-40910172-98.

A displacing agent with a viscosity higher than the viscosity of the displacing agent injected into the zone with medium permeability of 50% is pumped into a zone with a high permeability of a collector of more than 500 mD, i.e., 50%, i.e. 3.36 mPa * s, and the injection is carried out with a period of 9 days - injection, 9 days - stop. As a displacing agent, a 0.005-0.006% PAA solution is used. PAA is used in the form of an 8% concentration according to TU 6-02-00209912-61-97 or granular sulfate under the name PAA-GS according to TU 2216-001-40910172-98.

As a result, the development of all zones of the reservoir is achieved simultaneously after 32 years by achieving a final oil recovery of 38.5%.

Application of the proposed method will achieve uniformity of the development of zones of deposits ..

Claims (1)

A method of developing a heterogeneous oil reservoir, including dividing the reservoir into zones of high, medium and low permeability, injecting displacing agents with different viscosities into different zones through injection wells and selecting reservoir products through production wells, characterized in that the zone with low permeability is up to 100 MD injected displacing agent with a viscosity equal to the viscosity of produced water cyclically with a periodicity of 15 days, in a zone with an average permeability of the reservoir from 100 to 500 MD injected displacing agent from bone is higher than the viscosity of the displacing agent injected into the zone with low permeability, 40% cyclically with a periodicity of 12 days, the displacing agent with a viscosity higher than the viscosity of the displacing agent injected into the zone with an average permeability, 50% cyclically with a frequency of 9 days.