RU2148160C1 - Method of formation permeability control - Google Patents

Abstract

FIELD: oil-producing industry, particularly, method of restriction of water inflow into oil and gas wells and equalization of injectivity profile. SUBSTANCE: method includes injection into formation through injection or producing well of emulsion- and gel-forming solutions. In so doing, emulsifying fringe is injected before and after introduction of gel-forming solution with volume ratio from 1:1:1 to 1:2:1. Emulsifying fringe is formed from solution of surfactant in oil. Used as gel-forming solution is mixture of zeolite dissolved in alumochloride and aqueous solution of hydrochloric acid. EFFECT: reduced permeability of flooded highly permeable reservoir and higher profitability of oil production due to use of cheap reagents and simplified process of composition preparation. 3 cl, 2 cl

Description

 The invention relates to the oil and gas industry, in particular to methods for limiting water inflow into oil and gas wells and aligning the injectivity profile in injection wells.

 A known method of displacing oil from heterogeneous reservoirs by controlling the permeability of a gel-forming composition based on a zeolite-containing component manufactured in accordance with TU 38.1011366-94 and hydrochloric acid (Ovsyukov A.V. et al. Study of a gel-forming composition based on a zeolite-containing component. Oilfield business, N 11, 1996, p. 25). A disadvantage of the known technical solution is the low technological and economic efficiency.

 The closest in technical essence is the method of developing oil fields, which consists in injecting into the formation through the well an emulsion-forming rim, a gel-forming rim and again an emulsion-forming rim (see patent RU N2094601, E 21 B 43/22, 10.27.1977).

 The objective of the invention is to increase the efficiency of reducing the permeability of a watered high-permeability reservoir and increasing the profitability of oil production by using cheaper reagents and simplifying the technology for preparing the composition.

 This problem is achieved by the fact that in the method for controlling the permeability of the formation by injecting a gelling solution into the formation through an injection or production well, an emulsifying rim is pumped before and after the gelling solution is injected, and reagents are used as a gelling solution in the following ratio, wt.%: Zeolite 4 - 8, aluminum chloride 5-14, hydrochloric acid 2-4, the rest is water; and as an emulsion-forming rim, a solution of a nonionic surfactant in oil is used, and the emulsion-forming and gel-forming rims are supplied at a volume ratio of 1: 1: 1 to 1: 2: 1.

 The introduction of aluminum chloride in the gel-forming composition allows, according to laboratory studies, to increase the strength of the resulting gel, which allows you to save the gel formed in the reservoir at high pressure gradients. The process of preparing the working solution is also simplified. Zeolite in a solution of aluminum chloride can be prepared in advance on a reagent base, only then the addition of an aqueous solution of hydrochloric acid is carried out in the well, which allows to increase manufacturability and simplify the process of preparation and injection of the composition.

 The injected composition in the reservoir conditions after a certain time forms a gel that has increased strength and helps to limit the filtration of the injected water in highly permeable washed sections of the reservoir.

 The physicochemical nature of the application of the method lies in the fact that the first emulsion-forming rim in the form of a nonionic surfactant emulsion in oil is filtered into the most permeable areas and cracks, forming structured emulsions when interacting with water. The second, gel-forming rim, based on zeolite, aluminochloride and hydrochloric acid, being a true solution, is filtered into the washed pore zone of the site, and the gel forms directly in the formation. The third, emulsifying rim based on oil and nonionic surfactants, isolating the gel composition, creates favorable conditions for the formation of a strong gel.

Alumochloride - a product obtained by washing with a solution of aluminum chloride a reaction mass during the alkylation of benzene with propylene; is a waste product of isopropylenebenzene produced in accordance with TU 38.102163-84. Alumochloride is a liquid of light yellow or gray with a greenish tint in color with a density of 1.181-1.247 g / cm ³ with the content of the main substance in terms of AlCl ₃ in the range of 200-300 g / l.

Zeolite is a mineral, it contains oxides of silicon, sodium, aluminum, potassium, - NaAlSiO ₄ (2 ... 3) H ₂ O, manufactured according to TU 381011366-94.

 Technical hydrochloric acid is produced in accordance with GOST 857-88. It is an aqueous solution of hydrogen chloride (HCl) with a concentration of 31.5-35.0%, depending on the brand. In appearance, a clear, colorless, yellowish or yellow liquid.

 The method is as follows.

Stop the injection well, injected sequentially first rim emulseobrazuyuschuyu - 0.02% solution of nonionic surfactant (AF ₉ -12, -6 AF _9, Neftenol) in oil, and then trimmed to form a gelling mixture of zeolite alyumohloride and hydrochloric acid. Then the third rim is injected - an emulsifying solution of nonionic surfactants in oil. Then carry out the sale of waste water. After the completion of the process, the well is stopped for response for 72 hours.

 A comparison of the known and proposed methods was carried out according to the results of laboratory and field experiments.

Example 1. The optimal mass ratios of the components of zeolite, aluminochloride, hydrochloric acid are selected by the duration of the gelation time. The most convenient for commercial implementation of the method, the duration of gelation is a period of from 8 to 72 hours. From the table. 1 shows that the optimal mass ratios of the components were: zeolite 8%, alumina chloride 5 - 14%, hydrochloric acid 2 - 4%. A comparison of the methods in the laboratory was carried out according to the results of reducing the permeability of the porous medium. In filtration experiments, samples of a porous medium 300 mm long, 50 mm in diameter, filled with quartz sand or ground limestone fractions of 0.05-1.20 mm were used. The cores were pre-saturated with waste water with a density of 1156 kg / m ³ . Filtration was carried out at a constant pressure drop. Permeability was determined by filtering wastewater. Injected 100 ml of a gel-forming solution according to the prototype (experiment 1), as well as emulsion-forming and gel-forming rims according to the proposed method in the volume ratios indicated in the table. 2 (experiments 2 to 5).

 From the results of experiments on the study of filtration properties when applying the known technical solutions and the proposed method for the development of oil fields, are given in table. 2, it is seen that the inventive method can significantly improve the degree of decrease in permeability of the water-saturated part of the formation, thereby increasing the coverage of the formation by water flooding. With a volume ratio of rims from 1: 1: 1 to 1: 2: 1, the decrease in the permeability of the formation model in water reaches 76.9 - 95.6%, which is 26.9% higher than when applying the known method.

Example 2. The reservoir D1 is operated by 1 injection and 4 production wells. The effective oil-saturated thickness is 5.7 m. The density of the injected water is 1118 kg / m ³ . The well injectivity at 9.5 MPa 320 m ³ / day. The permeability of the formation of 0.18 - 0.24 μm ² . The water cut of production wells 93 - 96%, the average daily oil flow rate of 3.2 - 6.4 m ³ / day.

Before and after injection of the gelling composition, an emulsifying rim was supplied in a volume of 24 m ³ (0.5 m ³ Neonol AF ₉ -6 and 23.5 m ³ oil). The gel-forming composition included 2 tons of zeolite in 24 m ^{3 of} 22% alumina and 20 m ^{3 of a} solution of 8% hydrochloric acid. The well was stopped for response for 72 hours.

 The decrease in water cut in production wells after injection ranged from 10 to 50%. Technological efficiency in the form of additional oil production for the analyzed period amounted to 6170 tons of oil.

Example 3. The known method is tested in a pilot area, operated by 1 injection and 5 production wells, reservoir D1. The effective oil-saturated thickness is 6.2 m. The density of the injected water is 1156 kg / m ³ . The injectivity of the injection well at 10 MPa 300 m ³ / day. The water cut of production wells 92 - 94%, oil flow rates of 4.6 - 7.5 m ³ / day.

50 m ^{3 of} blocking solution was pumped into the injection well, which was prepared by mixing 5 tons of nepheline, 12 m ^{3 of} technical inhibited hydrochloric acid with a concentration of 26 wt.% And 28 m ^{3 of} injected water. After completion of the injection of the plugging solution, the bottom hole is cleaned by washing the well and the annulus of the well with water and pushing the solution of injected water with a volume of 40 m ³ . The well is then stopped for a gelation reaction for 72 hours.

 As a result of the application of the method, the reduction in water cut in production wells amounted to 5.0 - 8.0%. Additionally produced 1900 tons of oil, which is significantly lower than when using the proposed method.

Claims (2)

1. The method of controlling the permeability of the formation by injection into the formation through an injection or production well emulsifying rim, gelling solution and then again emulsifying rim, characterized in that reagents are used as gelling solution in the following ratio, wt.%:
Zolite - 4.0 - 8.0
Alumochloride - 10.0 - 28.0
Hydrochloric acid - 2.0 - 4.6
Water - Else
2. The method according to p. 1, characterized in that as the emulsion-forming rim, a solution of a nonionic surfactant in oil is used.  3. The method according to p. 1, characterized in that the emulsion-forming rims and the gel-forming solution are supplied at a volume ratio of from 1: 1: 1 to 1: 2: 1.

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