RU2114286C1 - Method for development of oil deposit - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: according to method, determined in oil deposit are similar worked out interlayers both in producing wells and in injection wells. At the same time injected into producing wells is isolating gel-creating compound, and pumped into injection wells is sediment-creating compound. Aforesaid procedure helps increase oil recovery from bed and reduce watering of recovered oil. EFFECT: higher efficiency. 2 cl, 1 tbl

Description

 The invention relates to the oil industry, in particular to increasing oil recovery at a late stage of development and reducing water cut in producing wells.

 There is a method of developing a water-cut oil reservoir, which includes injecting into the formation through an injection well an aqueous solution of a multivalent metal salt and an aqueous alkali solution [1].

 The disadvantage of this method is that it does not provide a long isolation period, since as a result of the interaction of these reagents, a fine precipitate of aluminum hydroxide that does not adhere to the rock is formed, which can be quickly washed with pumped water.

 Closest to the claimed solution is a method of developing an oil reservoir, including studying a section of a formation, isolating reservoirs of the same geological and physical characteristics in production and injection wells, and simultaneously processing the bottom-hole zone therein [2].

 The disadvantage of this method is that it is of a general nature and there is no solution to a specific technological problem, in particular, a decrease in the water content of the produced products during the operation of deposits at a late stage of their development.

 The objective of the invention is to increase oil recovery and reduce water cut of produced products due to the isolation of developed high-permeability formations and connection to the development of low-permeability formations.

The essence of the invention lies in the fact that in the method of developing an oil reservoir at a late stage, including the simultaneous isolation of the same produced layers in both production and injection wells to reduce the water content of the produced products, an insulating gel-forming composition is injected into production wells, including sodium silicate, hydrochloric acid and water, in the following ratio of components, wt.%:
Silicate of sodium (potassium) - 3 - 10
Hydrochloric acid - 3 - 5
Water - Else
and to isolate the fractured and highly permeable washed zones of the formation in order to increase the filtration resistance and cover the formation by exposure to injection wells, a sediment-forming composition is injected, including sodium silicate, ammonium chloride (calcium, aluminum) and water in the following ratio, wt.%:
Sodium Silicate - 5 - 20
Ammonium Chloride - 1 - 20
Water - Else
In the inventive method, it is proposed to pump a water repellent in a volume twice as large as the volume of insulating material before injecting the insulating composition into production wells to create additional resistance during water filtration and improve the permeability of the hydrocarbon phase of the formation fluid.

 The essence of the invention is as follows: in order to connect previously unreached oil-saturated zones of a formation to development, it is necessary to isolate the most watered-out highly permeable formations (interlayers); for this, a set of measures is taken to limit water inflow in production wells and to align the injectivity profile in injection wells.

 Standard hydrodynamic and geophysical surveys are carried out at the fields and according to their results, the most waterlogged areas are distinguished, in which the producing and injection wells have a hydrodynamic connection with each other, i.e. the displacing agent injected into the injection wells moves along the interlayers or section of the formation from which production is extracted by production wells.

 At the site, injection and production wells are simultaneously stopped and insulation work is carried out by injecting an insulating composition into the waterlogged interval of the production well, using an acid gel based on sodium silicate. The recommended composition has an adjustable gelation time in a wide temperature range, forms a strong gel that does not deteriorate with prolonged mechanical stress, unlike brittle alkaline silicate gels, which decompose into water and sediment. It has adhesion to the rock. Physico-chemical properties of the acid gel are presented in the table.

 Simultaneously with the isolation of water in the producing wells, the injectivity profile of the formation of the same name is equalized by injecting a sediment-forming composition through injection wells to increase the filtering resistance and the coverage of the formation with the effect and, as a result, involving previously non-working zones of the formation.

 To regulate the injectivity profile, various disperse systems or solutions are used, during the interaction of which a precipitate precipitates, but the best result was obtained using a solution of sodium silicate and a solution of ammonium chloride as the precipitate system.

 The insulating compositions used for the implementation of the technological process according to the proposed method are distinguished by the simplicity of preparation, the minimum number of components.

 Sodium silicate, ammonium chloride, hydrochloric acid are not deficient and environmentally friendly.

Example. The Agan oil field in the Nizhnevartovsk region is developed using in-situ flooding. The main reservoir BV ₈ lies at a depth of 2300 m, the temperature of the reservoir is 75 ^o C. The thickness of the reservoir is 10 m. The wells are perforated to the entire thickness of the reservoir. At present, the water cut of extractive products is 87.5%.

Productive stratum BV _{8 is} operated through 494 producing wells; water is pumped through 144 injection wells to maintain reservoir pressure.

 To carry out the technological process according to the proposed method, geophysical studies were carried out at this field and a site was selected where several production and injection wells are located that have comparable characteristics by reservoir conditions.

100 m ^{3 of} hydrophobizator was pumped into the irrigated production wells, then 40 - 50 m ^{3 of a} gel-forming composition was injected onto the surface, which was pushed into the reservoir by a hydrophobizer in a volume of 20 - 30 m ³ , after which the wells were stopped for gelation for 36 hours.

At the same time, 100 - 150 m ^{3 of} sediment-forming composition was pumped into injection wells and 60 - 80 m ^{3 of} water was pushed into the formation. After holding for 24 hours, they were put into operation simultaneously with production wells.

 As a result, the washed zones in the reservoir were blocked by a screen, the displacing agent moved through the new channels in the reservoir, displacing oil, which ensured a decrease in water cut in wells from 80 - 90 to 55 - 60%.

Claims (2)

 1. A method of developing an oil reservoir at a late stage, including the simultaneous isolation of the produced wells of the same name in both production and injection wells, characterized in that an insulating gel-forming composition is pumped into production wells, and a sediment-forming composition is pumped into injection wells to align the injectivity profile. 2. The method according to claim 1, characterized in that as the insulating gelling composition using sodium silicate, hydrochloric acid and water in the following ratio of components, wt.%:
Sodium Silicate - 3 - 10
Hydrochloric acid - 3 - 5
Water - Else
3. The method according to p. 1, characterized in that as the precipitating composition using sodium silicate, ammonium chloride and water, in the following ratio of components, wt.%:
Sodium Silicate - 5 - 20
Ammonium Chloride - 1 - 20
Water - Else

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