RU2136869C1 - Method of developing oil deposit - Google Patents

Abstract

FIELD: oil and gas production. SUBSTANCE: method consists in consecutively injecting edges of aqueous solution of a biopolymer together with water-soluble biological surfactant and liquid glass at preferable ratio 1:1: (0.04-0.2). EFFECT: increased efficiency of development resulting in increased oil recovery due to reduced water permeability of washed formation bottoms. 2 cl, 1 tbl, 2 ex

Description

 The invention relates to oil production using aqueous solutions of bioreagents.

 The main task in the development of oil fields at a late stage is to reduce the water cut of oil and the amount of produced water. For this, polymer, silicate-alkaline technologies, as well as other flow diverting technologies are effectively used. However, the development of new environmentally friendly, easy to implement, based on the use of available reagent technologies is an important practical task.

 It is known to use a solution of hydroxyethylated alkyl phenol and polyacrylamide with liquid glass to develop an oil field. A.S. SSR N 1736228, 1990. The main disadvantage is the low efficiency of the method due to the formation of various sparingly soluble structures with low filterability in the formation and their susceptibility to destructive processes.

 The closest analogue to the claimed method is a method of developing an oil field, including the sequential injection of biopolymer and liquid glass, the so-called isolation technology of highly permeable formation zones with silicate-biopolymer gels (All-Russian Research Institute named after Acad. Krylov A. P. report on D.88.001.03 " To develop the fundamentals of a technology for increasing oil recovery using bioreagents ". Moscow, 1990).

 The disadvantage of this method is the low efficiency of additional washing of residual oil.

 The objective of the invention is to increase the efficiency of the method by reducing the water permeability of the washed zones of the reservoir, improving the washing properties and enhanced oil recovery.

 The problem is solved in that in the method of developing an oil field, which includes the sequential injection of the rims of the Simusan biopolymer solution and liquid glass, the rim of the Simusan biopolymer solution is injected together with the biological surfactant bio-surfactant KSHAS-M. Moreover, the rims of the reagent solutions are pumped at a ratio of bio-surfactant KSHAS-M: biopolymer "Simusan": liquid glass, equal to from 1: 1: 0.04 to 1: 01: 0.2.

 KSHAS-M bio-surfactant according to TU 9291-015-00479770-96 is a natural bio-surfactant composition of glycolipid nature produced by the microorganism culture Pseudomonas acruginosa S-7. KSHAS-M has the ability to reduce the surface tension of water to 30 mN / m and interfacial activity to 1 mN / m. Biopolymer "Simusan" according to TU 64-13-127-88 is a culture fluid of the microorganism Acinetobacter SP. Liquid glass in accordance with GOST 13078-81.

 Liquid glass provides chemical interaction with biopolymer molecules, bio surfactants and multivalent metal salts of formation mineralized water, which ultimately leads to the formation of a strong reinforcing mesh that effectively reduces the permeability of washed zones and increases the coverage of the formation by water flooding and significantly improves the oil displacement process.

The above allows us to conclude that the claimed technical solution meets the criterion of "inventive step"
The specific composition of the gel-forming silicate-bio-surfactant-biopolymer solution and its injection into the reservoir is selected depending on the geological and physical conditions of the deposits: reservoir temperature t ^o , reservoir water composition, mineralogical composition and reservoir heterogeneity.

 The composition is pumped into an injection or production well, advanced in highly permeable layers, in low-permeability zones the penetration depth is much less.

 After a certain gelation time, the liquid composition turns into a visco-elastic gel throughout the volume filled with the gel-forming solution. This gel swab prevents the penetration of water into highly permeable zones and cracks. The regulation of sedimentation in the reservoir is achieved by the volume of the buffer rim of fresh water.

 The effectiveness of this method was determined by a known method (OST 39-195-88). Oil. A method for determining the coefficient of oil displacement by water in laboratory conditions. Minnefteprom.M.) experimentally on the change in the mobility of water before and after injection of reagent solutions and on the coefficient of oil displacement of residual oil.

 Example 1

Comparative experiments were performed when the residual oil was displaced from reservoir models 40 cm long, 2.8 cm in diameter, represented by core samples of natural sandy rocks with an average permeability of 0.8-1.0 μm ² . Bound water is created in the sandstone samples, the prepared model is saturated with oil with a viscosity of 18.0 MPa • s. At a horizontal position, oil is displaced from the reservoir model by mineralized water (salt content 140 g / dm ³ ) at a volumetric flow rate of 6 cm ³ / h until pressure drop is stabilized and water outflow from the reservoir model is completely irrigated. Then, a rim of fresh water and a rim of solutions of bio-surfactant bioreagents and biopolymer, which is pushed by the rim of liquid glass at a ratio of 1: 1: 0.1, are fed into the reservoir model. Then a rim of fresh water is pumped in and the experiment is stopped for a reaction for 24 hours. After that, mineralized water is again pumped into the reservoir model. The decrease in water permeability reached 73.8%, and the increase in oil recovery amounted to 8.1%.

 Example 2

 By the same methodology, an experiment is carried out to reduce permeability and displace oil by water, pumped after filtering the rims of the biopolymer and the liquid section at a ratio of 1: 0.1, respectively. The degree of decrease in water permeability is 49.4%. The increase in oil recovery due to increased coverage was 4.8% (prototype).

An example of a specific implementation of the method in the field
The Arlan field is characterized by heterogeneous formations with an average permeability of 0.7-0.9 μm ² , porosity of 0.2-0.25 and mineralized formation waters with a salt content of 140-250 g / dm ³ . The depth of the oil reservoir is about 1300-1500 m, the average thickness is 6 m. The reservoir is opened by one injection and one producing well; well grid density 12 ha / well Oil water cut 90%, i.e. the field is at a late stage of development. To implement the method, the injection of wastewater into the injection well is stopped and 30 m ^{3 of} fresh water is pumped into it. Then a mixture of bio-surfactants bio-surfactant-KSHAS-M and Simusan biopolymer in a volume of 50 m ³ is injected into one well and a liquid glass solution in a volume of 30 m ³ with a bio-surfactant: biopolymer: water glass ratio of 1: 1: 0.1. The injection is carried out by the CA-320 unit for 8-10 hours. The well is stopped for 1 day per reaction. After treatment, the reservoir is further exploited by conventional waterflooding.

 The proposed method is highly effective for enhancing oil recovery at a late stage of development.

Claims (2)

 1. A method of developing an oil field, including the sequential injection of rims of solutions of the Simusan biopolymer and liquid glass, characterized in that the rim of the solution of the Simusan biopolymer is pumped together with the biological surfactant bio-surfactant KSHAS-M.  2. The method according to p. 1, characterized in that the rims of the reagent solutions are pumped at a ratio of bio-surfactant KSHAS-M: Simusan biopolymer: liquid glass, equal to from 1: 1: 0.04 to 1: 1: 0.2.

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