RU2283949C1 - Oil field development method - Google Patents

Abstract

FIELD: oil production industry, particularly to stimulate oil production with the use of chemical reagents.

SUBSTANCE: method involves injecting solution through injection well via tubing string; providing solution decomposition to generate heat; injecting water; lifting oil via productive wells. The solution is 50% hydrogen peroxide and solution volume is equal to 0.3 of void volume. Hydrogen peroxide is supplied between two plugs with the use of liquid, which is inert to hydrogen peroxide. Volume of above liquid is equal to 1.1 tubing string volumes. Catalyst, for instance potassium hydroxide, is injected in well before the first plug forming. Potassium hydroxide volume is equal to 0.1 hydrogen peroxide volume. After two plugs forming 5% solution sodium permanganate is supplied in well and then oil is displaced to producing wells by water. The liquid, which is inert to hydrogen peroxide, is acetate bumper.

EFFECT: increased efficiency of residual oil production due to improved action on bound water.

2 cl

Description

The invention relates to the oil industry and can be used to intensify oil production using chemicals.

A known method of heat treatment of the bottom-hole zone of a well using hydrogen peroxide (Beiles J.X., A new method of heat treatment of the bottom-hole zone of a well using hydrogen peroxide, "Oil and Gas Technologies", No. 5-6, 1998). The method involves the injection into the formation of hydrogen peroxide in the amount of approximately 1564 liters per meter of power of the produced formation, technological exposure for the decomposition of 40% hydrogen peroxide for about 25 days and the subsequent commissioning of the well. Also in the method, options for using 30% and 50% hydrogen peroxide concentrations are considered. The disadvantage of this method is the long shutdown period of an oil well, as well as its applicability mainly for cleaning the bottom-hole zone of a well and the low efficiency of using the released energy.

A known method of developing an oil field, adopted as a prototype (RF patent No. 2021496, E 21 B 43/22, E 21 B 43/24, 1994.10.15). The method includes the injection through injection wells of a 1.0-10.0% aqueous solution of ammonium salt, heating the solution in the formation and oil production through production wells, according to the invention, in order to increase oil recovery, ammonium carbonate and ammonium nitrate are injected in the form rims with a size of 0.2-0.4 pore volume, and then an aqueous solution of a mixture of ammonium nitrate and sulfuric and hydrochloric acid pH 0.3 is pumped in the form of a rim of 0.1-0.4 pore volume with subsequent injection of water. Also, the method is characterized in that between the rims of aqueous solutions of ammonium carbonate and a mixture of ammonium nitrate and hydrochloric and sulfuric acid, a rim of water of 0.05-0.2 pore volume is pumped. The disadvantage of this method is the low efficiency in the production of residual oil associated with a weak effect on bound water in the oil reservoir.

The technical result of the method is to increase the efficiency of residual oil production due to the increased impact on bound water.

The technical result is achieved in that in a method for developing an oil field, including a rim, injecting a solution through an injection well through a tubing and decomposing it in a formation with heat generation, followed by water injection, lifting the oil through production wells according to the invention as a solution into the injection the well is supplied with 50% hydrogen peroxide in a volume equal to 0.3 per volume, moreover, hydrogen peroxide is fed between two rims with a liquid neutral to hydrogen peroxide, the volume of liquid neutral to hydrogen peroxide is taken to be 1.1 from the volume of the tubing, and before the first rim, a pre-point is carried out with a catalyst - potassium hydroxide, in a volume of 0.1 from the volume of hydrogen peroxide, 5% are fed after two rims sodium permanganate solution, after which oil is displaced to production wells using water.

The technical result is also achieved by the fact that an acetate buffer is used as a liquid neutral to hydrogen peroxide.

The application of the proposed method in comparison with the prototype can improve the efficiency of extraction of residual oil by increasing its impact on bound water.

After the operations of the method for developing an oil field in an oil reservoir are carried out, the reaction of the interaction of the produced and injected water with hydrogen peroxide begins, which is accompanied by the release of heat, which leads to the thawing of the reservoir and the splitting of the molecules of the bound water. It is known that one of the main reasons for the low oil recovery is specific hydrophobic interactions on the rock surface in the presence of water. The interaction of oil with porous media is hydrophobic and a change in hydrophobic interactions regulates the activity of oil displacement. Bound water adsorbed on a rock surface is similar in structure to a solid (condensation-crystallization structures). For a number of reservoir models, after exposure to reagents, a new phase of bound water is observed, which reduces oil recovery. A significant part of the reagent is irreversibly absorbed by the mobile component of the bound water, changing its physical and mechanical properties (viscosity). The problem of the interaction of 50% hydrogen peroxide with bound water was solved by the field theory method and quantum statistics based on modern models of bound water. In the temperature range above 343 K, phase separation of bound water was observed, including the stationary component included in it, with the release of the free water phase. Thus, the destruction of the structure and the removal of physically bound water occurs.

Hydrogen peroxide is a weak dibasic acid (K _dI = 2.6 · 10 ^-12 ). In an aqueous solution, it dissociates in a very insignificant degree into ions:

Dissociation in the second stage practically does not occur, since it is suppressed by the presence of water, a substance that dissociates with the formation of hydrogen ions to a greater extent than hydrogen peroxide.

However, with the introduction of a catalyst - potassium hydroxide into a solution of hydrogen peroxide, it becomes possible due to a shift of the reaction equilibrium to the right, the dissociation of the latter in the second stage:

обладающий восстановительными свойствами:as a result of which an active ion is formed

possessing reducing properties:

The introduction of manganese (IV) oxide into the system, which is a strong oxidizing agent, initiates the decomposition of hydrogen peroxide, creating a redox couple with the Mn ^{2+ ion}

As a result of the redox process with the participation of hydrogen peroxide, manganese (IV) oxide and potassium hydroxide, there is an active process of formation of free molecular oxygen and the release of a large amount of heat, which can be schematically expressed by the equation:

To maintain a constant pH of the medium, an acetate buffer is introduced:

Thus, due to the decomposition of hydrogen peroxide with the active participation of potassium hydroxide and manganese (IV) oxide in the reservoir will be present: oxygen gas, manganese ions Mn ²⁺ potassium K ⁺ and acetate CH ₃ COO ^- .

A method of developing an oil field is as follows. In the oil-bearing formation through the injection well, a pre-point is pumped with a catalyst — potassium hydroxide in a volume of 0.1 volume of hydrogen peroxide to activate the formation of free molecular oxygen and release more heat during the decomposition of hydrogen peroxide. Then, a rim is made with a liquid that is neutral to hydrogen peroxide in a volume equal to 1.1 of the volume of the tubing for washing and ensuring the absence of decomposition of hydrogen peroxide directly in the tubing, as well as for isolating the formation zone from the influx of formation water and determining the injectivity of the formation . After that, 50% hydrogen peroxide is injected into the formation in a volume equal to 0.3 of the pore volume of the oil-bearing formation to ensure the greatest thermal effect on the formation. The use of 50% hydrogen peroxide and its supply in the amount of 0.3 pore volume will allow for effective impact on the oil reservoir due to decomposition with the release of heat directly in the depth of the oil reservoir. Then, a second rim is carried out with a liquid neutral to hydrogen peroxide in a volume equal to 1.1 of the volume of the tubing to flush and ensure that hydrogen peroxide is not decomposed directly in the tubing and to ensure that hydrogen peroxide does not interact with vending water to increase safety production work. After the second rim, a 5% solution of sodium permanganate is fed into the formation to initiate a reaction with a large heat release. After that, with the help of water, oil is displaced to production wells. As a liquid neutral to hydrogen peroxide, you can use acetate buffer having the chemical formula of the form CH ₃ COOH + CH ₃ COONa (5% solution), which will improve the safety of the process. As a catalyst, for example, a 5% solution of manganese can be used, which allows to increase the heat of decomposition of the solution in the oil reservoir. The volume of a 5% solution of manganese is taken depending on the pore volume of the oil reservoir and the injectivity of the injection well.

The application of the proposed method for the development of an oil field provides the following advantages:

- the possibility of producing residual oil from depleted reservoirs;

- increasing the mobility of oil by reducing its viscosity;

- reduction in the cost of producing residual oil;

- increase the completeness of extraction of residual oil.

Claims (2)

1. A method of developing an oil field, including a rim, injecting a solution through a pumping well through an injection well and decomposing it in a formation with heat generation, followed by pumping water, raising oil through production wells, characterized in that the solution is supplied to the injection well as a solution 50% hydrogen peroxide in a volume equal to 0.3 pore volume, moreover, hydrogen peroxide is supplied between two rims with a liquid neutral to hydrogen peroxide, while the volume of liquid is neutral to peroxide and hydrogen, taken equal to 1.1 of the volume of the tubing, and before the first rim, a pre-point is carried out with a catalyst - potassium hydroxide, in a volume of 0.1 of the volume of hydrogen peroxide, after two rims, a 5% solution of sodium permanganate is fed, after which with the help of water, oil is displaced to production wells. 2. The method of developing an oil field according to claim 1, characterized in that an acetate buffer is used as a liquid neutral to hydrogen peroxide.