RU2302518C2 - Oil reservoir development method - Google Patents

Abstract

FIELD: oil industry, particularly to increase oil recovery from non-uniform reservoirs, namely high-temperature reservoirs, and from reservoirs with viscous and highly-viscous oil due to increased conformance and oil displacement factor.

SUBSTANCE: method involves flooding reservoir; producing oil through producing wells. Aluminum hydrochloride, namely waste product obtained during benzol alkylation with olefins, as well as buffer liquid and aqueous alkali solution are alternately injected in watered reservoir. Aluminum hydrochloride contains 0.05-10% of surfactant. Aqueous alkali solution also has 0.05-10% of surfactant. The buffer liquid is 0.05-10% aqueous surfactant solution. The aqueous alkali solution is modified alkali off-flow generated during caprolactam production. The aluminum hydrochloride containing above additive is activated aluminum hydrochloride.

EFFECT: increased oil production due to increased efficiency of high-permeable reservoir zones treatment by means of reservoir permeability reduction and final residual oil sweeping by gelling reagent injection through injection and producing wells to create gel mass with high structural-and-mechanical and oil-sweeping properties directly in reservoir conditions.

3 cl, 5 ex, 2 tbl

Description

The invention relates to the oil industry, in particular to methods for increasing oil recovery of heterogeneous reservoirs of oil fields by increasing the coverage of formations by exposure and increasing the oil displacement coefficient, and can be used in high-temperature formations, as well as in formations with viscous and high-viscosity oils.

A known method of isolating a permeable formation by sequential injection into the formation of aluminum chloride - waste production of alkylation of benzene with propylene and water glass (RF patent No. 1804548, MKI E21B 33/13, 1993). The disadvantage of this method is the insufficient volume of precipitate formed.

A known method of oil production by sequential injection into the reservoir of solutions of polyacrylamide and aluminum salt, and between them the injection of the rim of fresh water (RF patent No. 2086757, MKI E21B 43/22, 1997). The disadvantage of this method is the low efficiency of the method due to the low penetration depth into the reservoir.

A known method of developing an oil reservoir with a high-temperature formation, including injecting into the formation a mixture of solutions of aluminum chloride and trisodium phosphate, followed by forcing a solution of a surfactant into the formation (RF patent 2094599, MKI 6 Е21В 43/20, 1996). The disadvantage of this method is the low penetration depth of the resulting sediment into the reservoir and the complexity of the process.

The closest in technical essence and the achieved effect is a method of developing an irrigated oil reservoir, which involves injecting an aqueous solution of a multivalent metal salt into the formation, followed by injecting an aqueous solution of alkaline runoff of caprolactam production. This increases the efficiency of oil displacement (RF patent No. 2039224, MKI 6 ЕВВ 43/22, 33/138, 1992). The disadvantage of this method is the low oil washing properties.

The objective of the invention is to increase oil production by increasing the efficiency of processing highly permeable zones of the reservoir by reducing their permeability and re-washing residual oil by injecting reagents capable of forming a gel-like mass directly under formation conditions with high structural-mechanical and oil-washing properties through the production and injection wells.

The problem is solved in that in a method for developing an oil reservoir, including water flooding, oil extraction through production wells, injection of a working agent through injection wells and sequentially alternating injection of an aqueous alkali solution and an aqueous solution of a multivalent metal salt into a flooded formation, according to the invention, in an aqueous salt solution polyvalent metal and in an alkaline solution and in buffer water, surfactants are additionally introduced, while alkali stock produced by ca modified prolactam - ShchSPK-M, and activated aluminochloride is used as a salt of a multivalent metal with the addition of a surfactant.

The features of the invention are:

1. The selection of oil through production wells.

2. injection through the injection wells of the working agent.

3. injection through injection wells of sequentially alternating aqueous solutions of salts of a multivalent metal and an alkaline agent.

4. surfactant injection together with a multivalent metal salt and (or) alkaline reagent.

5. surfactant injection in the form of a separate rim between cycles of injection of an aqueous solution of a salt of a multivalent metal and an alkaline agent or (and) after them.

6. use as an aqueous solution of a salt of a multivalent metal with the addition of surfactant activated aluminum chloride.

7. use as an alkaline agent with the addition of surfactants - alkaline runoff modified caprolactam production.

Signs 1-3 are similar to the prototype, signs 4-7 are the salient features of the invention.

SUMMARY OF THE INVENTION

When developing an oil reservoir, a working agent (fresh or mineralized water), pumped through injection wells, displaces the oil mainly from the highly permeable zones of the reservoir. To clog highly permeable zones and direct the working agent into low-permeable oil-saturated zones, sequentially alternating rims of aqueous solutions of salts of a multivalent metal and an alkaline agent are pumped through injection wells. However, the efficiency of isolation and the degree of oil washing in this case, and, consequently, the development of the reservoir is low. The invention solves the problem of increasing the efficiency of oil displacement, not only by increasing the coverage of the formation by the impact, but also by increasing the oil displacement coefficient (increasing the degree of oil washing out) and, thus, increasing the oil recovery of the reservoir.

According to the proposed method, when developing an oil reservoir, oil is taken through production wells and the working agent is injected through injection wells. From time to time, in order to effectively influence the oil reservoir, successively alternating aqueous solutions of salts of a multivalent metal and an alkaline agent are pumped through injection or production wells. Surfactants are added to the injected reagents and injected as a separate rim between the injected reagents or after. At the same time, surfactants contribute to better penetration of reagents into the formation, which allows the injection of reagents into low-permeability formations. Under reservoir conditions, a gel-like precipitate forms, which is fixed on the surface of the pores and creates a residual resistance factor for water in the most permeable zones of the oil reservoir. At the same time, the surfactant contributes not only to the residual oil washing out due to the reduction of interfacial tension at the oil-displacing agent interface, but also to the creation of a more stable structure of the precipitate formed.

Working concentrations of reagents and their volumes vary depending on the injectivity of the well and the thickness of the treated formation. By changing the volumes of injected reagents and buffer water between them, it is possible to regulate the place of formation of gel-like sediment in the highly permeable zone of the oil reservoir.

When reagents are injected through injection wells, the reservoir coverage increases due to redistribution of filtration flows into low-permeability layers of the oil reservoir, and the oil displacement coefficient also increases. When reagents are injected into production wells, a gel-like precipitate forms that helps to isolate water and reduce water cut in the product.

To solve this problem, aluminum salts (aluminum sulfate, aluminum chloride, etc.), calcium, magnesium, iron, aluminum-containing waste from the production of benzene alkylation with olefins (aluminum chloride) and other aluminum-containing aqueous solutions, and aluminum-containing waste from the production of alkylation are used as an aqueous solution of a multivalent metal salt. benzene olefins are taken according to TU 38.302163-89.

As an aluminum-containing aqueous solution with a surfactant additive, take aluminum chloride activated according to TU 2458-002-42129794-2001 (aluminum chloride-A), obtained on the basis of waste from the production of alkylbenzene - aluminum chloride and activating additives (surfactants).

Activated aluminum chloride - a liquid of light yellow or gray color, with a greenish tint, the presence of a cloudy precipitate is permissible. According to TU 2458-002-42129794-2001 activated aluminochloride has the following quality indicators:

The concentration of the main substance (in terms of Al ³⁺ ), g / dm ³ - 35.0-65.0

The concentration of organic impurities, g / DM ³ , not more than 0.5

The concentration of suspended particles, g / dm ³ , not more than 0.5

The activity indicator of hydrogen ions - the pH of the solution is 0.8-4.0

The content of activating additives, wt.%, Not more than 2.0.

As alkali, an aqueous solution of sodium silicate, sodium carbonate, alkaline stock of caprolactam production according to TU 113-03-488-84 and TU 113-03-05761695-31-97 are used.

As an alkaline solution with the addition of a surfactant, an alkaline stock of caprolactam production is taken - modified (ЩСПК-М) according to TU 2432-001-42129794-2001.

ShchSPK-M is obtained on the basis of caprolactam production wastes and modifying additives; it is a light to dark brown liquid, opaque, and a precipitate is permissible.

According to TU 2432-001-42129794-2001 SCHSPK-M has:

Density at 20 ° С, g / cm ³ , no less than 1.0

Mass fraction of dry matter, wt.% - 12.0-45.0

Mass fraction of sodium salts of organic acids (in terms of sodium adipate), wt.% - 9.0-30.0

pH of the solution is 8.0-13.0

The content of modifying additives, wt.%, Not more than 2.0

As surfactants are water-soluble ionic and non-ionic surfactants TU 2483-077-05766801-98 "Neonols" (AF ₉ -4, ₉ -6 AF, AF ₉ -9 -10 ₉ AF, AFB-10, AP -12 ₉ , AFB-12), TU 38.40196-93 "Detergent additive for gasoline" Neolin-2 ", TU 2226-010-10488057-94 with amendment 1-9" Lapramol 294 ", etc.

When salts of a multivalent metal interact with alkaline agents with surfactant additives, a poorly soluble precipitate (aluminum hydroxide, aluminum adipate, copper hydroxide, iron hydroxide and other compounds, depending on the starting materials) is formed, which is fixed on the pore surface, and the surfactant contained reduces interfacial tension by the border "oil-displacing agent" and contributes to the laundering of oil.

Table 1 shows the results of laboratory studies, from which it is seen that the interfacial tension of solutions of polyvalent metal salts with surfactant additives, alkaline agents with surfactant additives, activated alumina chloride and alkaline runoff of caprolactam production modified by comparison with reagents without surfactant is lower by 28-99% .

Table 1 Way Reagent Name Interfacial tension σ,
mn / m The decrease in σ compared with the prototype,% According to the well-known Aluminum chloride 35,2 According to the proposed Alumochloride + 0.01% AF ₉ -12 14.2 60 Alumochloride +0.05 AF ₉ -12 0.5 99 Alumochloride-A 15.1 57 Alumochloride + 0.1% Neolin-2 5,6 84 Alumochloride + 0.1% Lapramol 8.9 75 According to the well-known Aqueous solution of aluminum sulfate 34.8 According to the proposed An aqueous solution of aluminum sulfate + 0.05% Neolin-2 8.3 76 According to the well-known ShchSPK 12.9 According to the proposed ShchSPK + 0.1% AF ₉ -12 0.8 94 ShchSPK + 0.1% Neolin-2 3.4 74 Trisodium phosphate aqueous solution + 0.05% AF ₉ -12 0.5 96 SCHSPK-M 9.3 28 An aqueous solution of sodium carbonate + 0.1% AF ₉ -9 2,4 81

The method is as follows.

Sequentially alternating rims of an aqueous solution of a multivalent metal salt and an alkaline agent with a concentration of 5% to the maximum possible (maximum concentration is limited by the solubility of the substance in water) with a buffer volume of water between them are pumped through injection wells and (or) production wells with a buffer volume of water between them to prevent their premature reaction. So spend 2-10 cycles in any sequence of injection of reagents. A multivalent metal salt and an alkaline agent are added or previously dissolved in aqueous solutions before injection of 0.05 ... 10% surfactant. An additional surfactant is not added to alumochloride-A and ShchSPK-M, since these reagents already contain a surfactant. Surfactants can also be injected in the form of a separate rim between the cycles of injection of aqueous solutions of a salt of a multivalent metal and an alkaline agent and / or after cycles of injection of reagents. Then leave the well to respond for 1-3 days, then put into operation in the same mode as before treatment.

Examples of specific performance of the method.

The method is implemented in laboratory conditions on models of an oil reservoir. The reservoir model consists of 2 metal tubes with a diameter of 33 mm, a length of 1 m, filled with sand with different permeabilities. After evacuation, the formation models are saturated with formation water, which is then replaced with oil. Oil is displaced by water to 100% flooding of a highly permeable layer and a constant pressure drop. In this case, the final coefficient of oil displacement by water is achieved with a high-permeability interlayer, and the oil displacement coefficient with an low-permeable interlayer has an intermediate value depending on the permeability of the porous medium. Then the edges of the reagents are pumped, after which further oil washing with water is carried out.

Example 1. By a known method, rims of aluminum chloride and alkaline runoff of caprolactam production are pumped. The residual resistance factor was 1.96, the increase in oil recovery coefficient was 7.2%, and the increase in displacement coefficient was 0.5% (table 2, experiment 1).

Example 2. According to the proposed method, aluminum chloride is added with the addition of surfactants AF _9-12 and ShchSPK with a buffer volume of water between them. The residual resistance factor was 2.10, which is 7% higher compared to the known method. The increase in oil recovery ratio amounted to 10.3%, which is higher compared to the known method by 3.1%. The increase in the displacement coefficient of a highly permeable layer (which characterizes the ability of the reagents to wash film oil) amounted to 3.5%, which is 3.0% higher than the known method (table 2, experiment 2).

Example 3. According to the proposed method is pumped rim alyumohlorida supplemented with AF ₉ -12, aqueous AF ₉ -12 and SCHSPK with a buffer volume of water therebetween. The residual resistance factor was 2.13, which is 9% higher than the prototype. The increase in oil recovery ratio amounted to 10.8%, which is higher compared with the known method by 3.6%. The increase in the displacement coefficient of the highly permeable interlayer was 4.0%, which is 3.5% higher compared to the known method (table 2, experiment 3).

Example 4. According to the proposed method, the activated aluminum chloride is injected, the buffer liquid is a 0.05% aqueous surfactant solution, and ShchSPK-M. The residual resistance factor was 2.05, which is 5% higher compared to the known method. The increase in oil recovery ratio was 13.4%, which is 6.2% higher compared to the known method. The increase in the displacement coefficient of the highly permeable layer was 7.4%, which is 6.98% higher compared to the known method (table 2, experiment 11).

Example 5. According to the proposed method, the activated aluminum chloride is injected, the buffer liquid is 0.1% aqueous surfactant solution, sodium silicate with 0.05% surfactant. The residual resistance factor was 2.60, which is 33% higher compared to the known method. The increase in oil recovery ratio amounted to 14.7%, which is higher compared to the known method by 7.5%. The increase in the displacement coefficient of the highly permeable interlayer was 4.0%, which is higher than the known method by 3.5% (table 2, experiment 15).

The data in table 2 show that when injecting an aqueous solution of a salt of a multivalent metal and an alkaline agent, surfactants are added to one or both of these reagents, as well as without and with additional injection of a surfactant solution in the form of a separate rim, it allows to increase the residual resistance factor compared to in a known manner by 5-33%, oil recovery coefficient increase - by 0.9-7.5%, oil displacement coefficient increase - by 2.6-8.5%.

As can be seen from table 2, the best oil recovery results were obtained using aluminum chloride with the addition of a surfactant, a buffer liquid — an aqueous surfactant solution, an aqueous alkaline solution with a surfactant additive (surfactant additive 0.05-10 wt.%).

Application of the proposed method will improve the efficiency of the method, increase oil recovery of the reservoir.

Claims (3)

1. A method of developing a heterogeneous oil reservoir, including water flooding, oil extraction through production wells, sequentially alternating injection of alumina chloride into the flooded reservoir — waste production of alkylation of benzene with olefins, a buffer liquid, an aqueous alkaline solution, characterized in that aluminochloride with the addition of 0.05- is used 10% surfactant surfactant, an aqueous alkaline solution with the addition of 0.05-10% surfactant, as a buffer liquid - 0.05-10% aqueous surfactant solution. 2. The method according to claim 1, characterized in that as the aqueous alkaline solution with the specified additive, the alkaline runoff of the production of caprolactam ShchSPK modified is used. 3. The method according to claim 1, characterized in that activated aluminochloride is used as alumina chloride with said additive.