RU2094601C1 - Method for development of oil deposit - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: this can be used for development of oil deposit in cyclic mode. Method implies periodic pumping of oil emulsion and working agent through injection wells, recovery of oil through producing wells. At periodic injection of oil emulsion, also effected is periodic injection of gel-formation material. Their equivalent volumes of injection prior to reduction of well injectivity is 30-70% lower than established earlier. Injection of working agent is effected up to reservoir pressure which exceeds initial pressure by 0.5-1.5 MPa with subsequent stoppage of injection wells until reservoir pressure is by 0.5-1.5 MPa below initial reservoir pressure. EFFECT: high efficiency.

Description

 The invention relates to the oil industry and can be used in the development of oil deposits in a cyclic mode.

A known method of developing an oil reservoir, including the injection of a working agent through injection wells and the selection of oil through production wells, periodic injection through injection wells of gelling material [1]
The known method does not allow to achieve high oil recovery.

Closest to the invention in technical essence is a method of developing an oil reservoir, comprising injecting a working agent through injection wells and taking oil through production wells, periodically injecting oil emulsions through injection wells [2]
The disadvantages of the method are the low oil recovery due to the low efficiency of isolation of the absorption zones of injection wells and the low duration of isolation.

 The purpose of the invention is the enhancement of oil recovery.

 This goal is achieved by the fact that in the known method of developing an oil reservoir, including periodic injection through injection wells of an oil emulsion and a working agent, oil selection through production wells, according to the invention, at periodic injection of an oil emulsion, periodic production of gel-forming material is carried out at their equivalent injection volumes until reduction injectivity of the well is 30-70% lower than previously established, and the injection of the working agent to exceed the reservoir pressure is 0.5-1.5 MPa higher than the beginning ceiling elements, followed by stopping the injection wells to achieve reservoir pressure at 0.5-1.5 MPa lower than the initial reservoir pressure.

Salient features:
1. Periodic injection through injection wells of oil emulsion and working agent.

 2. Oil extraction through production wells.

 3. During periodic injection of an oil emulsion, the production of periodic injection of a gelling material.

 4. Periodic injection of oil emulsion and gel-forming material at their equivalent injection volumes until the well injectivity decreases by 30-40% lower than previously established.

 5. Injection of the working agent to exceed the reservoir pressure by 0.5-1.5 MPa above the initial one.

 6. Subsequent shutdown of injection wells until the reservoir pressure is 0.5-1.5 MPa below the initial reservoir pressure.

 During the development of an oil reservoir, part of the reserves remains unreached, as a result of which the oil recovery of the reservoir is small. The task of increasing oil recovery is solved in this invention.

 The decrease in the permeability of the washed high-permeability zones leads to a leveling of the front of the displacement and extraction of oil from low-permeability zones. To clog high-permeability zones, insulating materials: oil emulsion and gelling material are pumped through injection wells. However, when only an oil emulsion or only a gelling material is injected, the effect of blocking highly permeable zones remains insignificant in magnitude and short in time.

 The reservoir is gradually adapting to the oil emulsion or to the gel-forming material, and with subsequent injections, the effect of their use decreases in magnitude and time.

 The combined use of oil emulsion and gelling material leads to the creation of a reliable plugging system in the reservoir, which has a reproducible result at each injection in terms of size and duration of treatment. With subsequent downloads, the efficiency of the system does not decrease. Apparently, under reservoir conditions, a plugging mixture is created with a synthetic effect.

 In addition, the cyclic mode of operation of injection wells also influences the oil recovery of the reservoir7 When the current reservoir pressure is increased, conditions are created for cracking, primarily in the highly permeable zone, where the insulating material rushes. With a decrease in pressure, cracks are closed and the insulating material is firmly fixed in highly permeable zones. Thus, conditions are created for moving the working agent through low-permeability, non-washed areas and oil displacement from them.

 The efficiency of blocking low-permeability zones is estimated by the injectivity of injection wells before injection and after injection of oil emulsion and gelling material. As a rule, a 30-70% reduction in injectivity guarantees the blockage of highly permeable zones and the entry of a working agent into low-permeability zones.

The magnitude of the excess and decrease in reservoir pressure during the injection of a working agent to a stop of injection wells was determined experimentally as giving the greatest oil recovery effect for this method. An oil deposit of the Muravlenkovskoye field is being developed with the following characteristics: depth 2653 m, reservoir size 29.5 x 13.5 km, reservoir type terrigenous, VNK absolute mark -2585 m, oil saturated thickness 15.5 m, average permeability 100 mD, average porosity 0.187, initial reservoir pressure 26.5 MPa, saturation pressure 12.0 MPa, reservoir temperature 84 ^o C, oil viscosity at reservoir conditions 0.97, gas saturation 59 m ³ / t, oil density at reservoir conditions 0.844 g / cm ³ , sandiness coefficient 0 , 65, dissection coefficient 4.85, coefficient discontinuation rate 0.18, porosity 22% oil saturation 70% volumetric coefficient 1.177 oil density at reservoir conditions 0.772 g / cm ³ , oil viscosity at 20 ^o C 12.7 cPs, water viscosity at reservoir conditions 1.007 g / cm ³ . Fund of producing wells 675, fund of injection wells 171.

 Associated produced water is pumped through 20 injection wells, and oil is taken through 80 production wells. Well placement system inline. The cyclic operating mode of injection wells is as follows: 15 days injection, 15 days shutdown.

At the initial moment of launching the injection well, an oil emulsion is injected in a volume of 30 m ³ and a gel-forming material in a volume of 30 m ³ , then again 30 m ^{3 of an} oil emulsion and 30 m ^{3 of a} gel-forming material, and so on, until the injectivity of the injection well decreases by 30-70 % lower than previously established. The injectivity of the well decreases from 500 m ³ / day to 150 m ³ / day. After that, they proceed to the injection of the working agent of associated formation water. The injection is continued until the reservoir pressure on the reservoir is higher than 27 MPa. After that, injection wells are stopped and oil is taken from the reservoir through 80 production wells until a reservoir pressure of 26 MPa is reached.

 As an oil emulsion, a mixture of stable gasoline of 14.2 tons with Neftenol NZ 3.7 tons and 0.9 tons of organosilicon liquid in 10 tons of water is used and everything is mixed.

 As a gel-forming material, a mixture of 0.5% polyacrylamide solution of 0.5 t, potassium dichromate 0.08 t, VVD neftenol (neonol) 1 t, KCCB lignosulfonate 0.3 t and water 12 t are used.

Oil recovery increased by 2%
Example 2. Performed as example 1. At the initial moment of launching the injection well, oil emulsion is injected in a volume of 40 m ³ and a gel-forming material in a volume of 40 m ³ , then again 40 m ^{3 of} oil emulsion and 40 m ^{3 of} gel-forming material, etc. until the injectivity of the injection well decreases by 30-70% below the previously established one. The injectivity of the well decreases from 600 m ³ / day to 300 m ³ / day.

 The injection of the working agent is continued until a reservoir pressure of 27.5 MPa is reached. Subsequent selection of oil after shutdown of injection wells is carried out until a reservoir pressure of 25.5 MPa is reached.

Oil recovery increased by 2.5%
Example 3. Perform as example 1. At the initial moment of launching the injection well, oil emulsion is injected in a volume of 50 m ³ and a gel-forming material in a volume of 50 m ³ , then again 50 m ^{3 of} oil emulsion and 50 m ^{3 of} gel-forming material and so on until reduced injectivity of the injection well is 30-70% lower than previously installed.

The injectivity of the well is reduced from 700 m ³ / day to 450 m ³ / day.

 The injection of the working agent is continued until the reservoir pressure on the reservoir reaches 28 MPa. Further oil selection after stopping the injection wells is carried out until a reservoir pressure of 25 MPa is reached.

 Oil recovery increased by 2.8%

Claims (1)

 A method of developing an oil deposit, including periodic injection of oil emulsion and a working agent through injection wells, oil selection through production wells, characterized in that during periodic injection of oil emulsion, gel-forming material is periodically pumped at their equivalent injection volumes to reduce well injectivity by 30 70% lower than previously established, and the injection of the working agent to exceed the reservoir pressure is 0.5 1.5 MPa higher than the initial one, with the subsequent shutdown of injection wells zhin until the reservoir pressure of 0.5 1.5 MPa below the initial reservoir pressure.