RU2263205C1 - Oil reservoir development method - Google Patents

Abstract

FIELD: oil production equipment, particularly for development oil reservoirs characterized by zonal non-uniformity and formed by terrigenous rock.

SUBSTANCE: method involves alternating injecting acid solution and polymer-and-alkaline solution beginning from acid solution, wherein the polymer-and-alkaline solution includes water-soluble carbonate , water-soluble polymer and water so that gaseous carbon dioxide is generated as a result of their reaction; forcing carbon dioxide plug with water. Acid solution is aqueous solution of hydrochloric acid, lignosulphonate, solvent and nonionic surfactant or aqueous solution of hydrochloric and/or hydrofluoric acid, solvent and nonionic surfactant or composition including hydrochloric acid in amount of 10.0-25.9 % by weight, nonionic surfactant in amount of 0.05-1.0 % by weight and water. After acid solution injection polymer-and-alkaline solution is forced, wherein the polymer-and-alkaline solution includes water-soluble carbonate in amount of 5.0-15.0 % by weight, water-soluble polymer in amount of 0.05-1.0 % by weight, remainder is water.

EFFECT: increased efficiency of oil reservoir development and, as a result, increased reservoir treatment area and increased oil recovery by forming oil-displacing agent directly in reservoir environment.

12 ex, 1 tbl

Description

The invention relates to the oil industry and is used in the development of oil deposits with zonal heterogeneity and composed of terrigenous rocks.

A known method of displacing oil from a lenticular reservoir, including sequential, batch, cyclic injection through an injection well of an aqueous solution of potassium carbonate with a concentration of 25-26 wt.% And a solution of inhibited hydrochloric acid with a hydrogen chloride content of 18-19 wt.% With an optimal ratio of their volumes and selection of products through the same or producing well (see RF patent No. 2065942, MKI E 21 B 43/22, publ. 1996). The known method is not effective enough.

There is a method of developing an oil deposit, which consists in displacing oil with a gas-liquid rim, pushed through the reservoir with water, and the gas-liquid rim is created by sequentially injecting an aqueous solution of sodium carbonate and an aqueous solution of hydrochloric acid in equal volumes (see patent No. 2125154, MKI E 21 V 43/22, publ. 1999). This method is not effective enough due to the formation in reservoir conditions of a gas-liquid rim with low viscoelastic properties.

The closest in technical essence and the achieved effect is a method of developing an oil deposit, which includes generating carbon dioxide rims, pushed through the reservoir with water, creating a carbon dioxide rim by injecting an aqueous solution of a medium carbonic acid salt with surfactant additives and a water-soluble polymer and an acid solution, and the injection of an aqueous solution of a carbonic salt with additives and an acid solution is carried out alternately (see RF patent No. 214 2557, MKI E 21 43/20, publ. 1999). The disadvantage of this method is its lack of effectiveness due to the poor solubility of nonionic surfactants (nonionic surfactants) in a polymer solution with a carbonic acid salt.

The technical result is the creation of a highly effective method of developing an oil reservoir, which allows due to the integrated impact on the reservoir to increase the coverage of the reservoir by the impact and the degree of oil recovery by creating an oil-displacing agent directly in the reservoir conditions.

In a method for developing an oil deposit, comprising alternating injection of an acid solution and a polymer-alkaline solution containing a water-soluble carbonic acid salt, a water-soluble polymer and water, with the formation of carbon dioxide, followed by pushing the carbon dioxide rim with the injected water, the acid solution is first pumped into, the quality of which the composition DN-9010 is used - an aqueous solution of hydrochloric acid, lignosulfonate, solvent and nonionic surfactant NPA In or SNPCH-9021 - an aqueous solution of hydrochloric and / or hydrofluoric acid, solvent and nonionic surfactants, or a composition including, wt.%:

hydrochloric acid 10.0-25.0

 Nonionic surfactants 0.05-1.0

water the rest

and then a polymer-alkaline solution, including, wt.%:

water soluble carbonic acid salt 5.0-15.0

water soluble polymer 0.05-1.0

water the rest

When implementing the method for preparing a polymer-alkaline solution as a water-soluble salt of carbonic acid, use, for example:

- soda ash (Na ₂ CO ₃ ) according to GOST 83-79;

- calcium carbonate (CaCO ₃ ) according to GOST 4530-76;

- ammonium carbonate (NH ₄ ) ₂ CO ₃ ) according to GOST 3770-75;

- potassium carbonate (K ₂ CO ₃ ) according to GOST 4221-76;

as a water-soluble polymer, for example:

- polyacrylamide (PAA), for example, according to TU 6-16-2531-81, TU 6-01-1049-81;

- sulfacell according to TU 2233-013-32957739-01;

- DKS-ORP F40 NT;

- Accotrol S622.

For the preparation of an acid solution as nonionic surfactants use, for example:

- ethoxylated alkyl phenols AF9-6, AF9-12 according to TU 2483-077-05766801-98;

- syntanol DS-10 according to TU 6-14.577-88;

- OP-10 according to GOST 8433-81.

To prepare the acid solution, 25% hydrochloric acid according to GOST 3118-77 or inhibited hydrochloric acid is used according to TU 39-05765670-OP-212-95.

DN-9010 is taken according to TU 38-40127-95.

SNPCH-9021 is taken according to TU 2458-OP-248-05765670-98.

The polymer-alkaline and acidic solution is injected in alternating mode. With a low injectivity of the injection well, an acid solution is first injected, which dissolves the rocks that make up the bottomhole formation zone, and then a polymer-alkaline solution, which neutralizes the remains of the acid solution. The injection of working agents is carried out in several cycles to ensure complete interaction of the reagents.

The polymer-alkaline and acidic solution is injected with an injection of buffer fluid between them in order to avoid premature gas formation on the surface or in the well. As the injected solutions move into the reservoir, CO ₂ will continuously form. The acid solution is pumped in excess in relation to the polymer-alkaline solution due to the fact that a certain amount of the acid solution is spent on interaction with the rock. To achieve the greatest effect, the polymer-alkaline solution is last injected. Next, pump water.

The use of the proposed method leads to a complex effect on the reservoir. Firstly, the injection of a polymer-alkaline solution, which mainly penetrates into water-saturated zones, leads to an increase in the coverage of the formation by exposure, and secondly, when two solutions interact, an oil-displacing agent is formed - carbon dioxide, which is pushed into the depth of the formation by injected water and promotes oil displacement . The effectiveness of the process of oil displacement by carbon dioxide is determined by its solubility in oil, causing a decrease in its viscosity. In addition, the dissolution of CO ₂ in water and oil leads to a decrease in interfacial tension at the boundary of these phases.

A new set of claimed essential features allows you to get a new technical result, namely: due to the integrated impact on the reservoir to increase the coefficient of oil displacement.

An analysis of the known solutions selected in the search process showed that there is no object in science and technology that is similar to the claimed combination of features and has high performance in the development of an oil deposit, which allows us to conclude that the claimed invention meets the criteria of "novelty" and "inventive step".

The method in the field is as follows. Depending on the injectivity of the injection well, an acid solution is sequentially pumped into a heterogeneous oil reservoir with a water cut of more than 60%, which is composed of terrigenous rock, and then a polymer-alkaline solution, or first a polymer-alkaline solution, then an acid solution and again a polymer-alkaline solution. After injection of each solution, buffer liquid is pumped in an amount of 3-5 m ³ . The indicated reagent injection sequence is one cycle; in total, 1-5 reagent injection cycles are carried out. The total number of injected reagents and the number of cycles depend on the injectivity of the wells and the thickness of the reservoir. Next, pump water.

To prove the conformity of the claimed invention to the criterion of "industrial applicability", we give specific examples of determining the effectiveness of the proposed method in laboratory conditions by indicators: an increase in the oil displacement coefficient and relative filtration rate.

Efficiency studies are carried out on bulk linear and paired models with a length of 20 cm and a cross section of 1.5 cm ² filled with quartz sand. Mineralized water with a salt content of 130 and 270 g / l and Devonian oil are used as saturating fluids. When conducting research on paired models, a given value of permeability is obtained by a certain set of quartz sand fractions. The injection of solutions and their displacement from the porous medium of the models is carried out at constant pressure.

During the research, the volumes of the rims of the solutions, the ratio of the components, the sequence of injection of solutions varied. The filtration rate is determined by the change in the expiration time of 1 cm ³ liquid at constant pressure. The relative filtration rate is calculated by the formula:

W = Wf / Ww, where:

Wf = V / t — fluid filtration rate after injection of solutions, cm ³ / min;

V = 1 cm ³ is the volume of liquid;

t is the expiration time of 1 cm ³ min;

Wв = V / t - water filtration rate before injection into the model of solutions, cm ³ / min. The research results are shown in the table.

Example 1 (the inventive method). First, an acid solution consisting of 10% wt. HCl based on dry matter (40 g of 25% HCl), 1.0% wt. nonionic surfactant AF9-12 and 89% wt. water in an amount of 10% PO, pushed with water, and then injected polymer-alkaline solution, consisting of 0.05% wt. PAA and 5.0% wt. sodium carbonate and 94.95% wt. water, in an amount of 30% PO. Next, pump water. The increase in oil displacement coefficient is 14.29%, and the relative filtration rate is 1.35 (see table, example 1).

Examples 2-9 are carried out analogously to example 1.

Example 10. In a model of a heterogeneous reservoir (paired models), a polymer-alkaline solution consisting of 0.5% wt. PAA, 10% wt. soda ash and 89.5% wt. water in an amount of 10% PO, the solution is pushed with water, then an acid solution is pumped, consisting of 25% wt. from HCl based on dry matter (99.9 g of 25% HCI) and 0.1% wt. nonionic surfactant - AF9-12 in the amount of 10% PO. Then pump water and then a polymer-alkaline solution in an amount of 20% PO, consisting of 0.5% wt. PAA, 10% wt. soda ash and 89.5% wt. water. Next, pump water. The increase in oil displacement coefficient on the runway 2.61%, and on the runway 22.86%, and the relative filtration rate on the runway 1.50%, and on the runway 0.83% (see table, example 10).

Example 11 is carried out analogously to example 10.

Example 12 (known method). A polymer solution consisting of 10.0 g of sodium carbonate, 1.0 g of surfactant sulfanol, 0.1 g of PAA and 88.9 g of water is sequentially injected into the linear model of the formation, then an acid solution of 40 g is pumped HCI (25%) and 60 g of water

Hold for 5 hours. Then the displacing agent is pumped. The growth rate of oil displacement is 10.61%, and the relative filtration rate is 0.28 (see table, example 12).

As can be seen from the table, the increase in oil displacement coefficient increases significantly, and the relative filtration rate indicators indicate that as a result of processing the oil reservoir with the declared solutions, the permeability of the formation increases, and when processing heterogeneous formations, by blocking highly permeable layers, the permeability of the highly permeable layer decreases , and the permeability of the low permeability layer - increases.

Using the proposed method allows you to:

- increase the coverage of the heterogeneous formation by exposure;

- increase the growth rate of oil displacement;

- effectively develop oil deposits by creating an oil displacing agent directly in the reservoir.

Claims (1)

A method of developing an oil deposit, comprising alternating injection of an acid solution and a polymer-alkaline solution containing a water-soluble carbonic acid salt, a water-soluble polymer and water, with the formation of carbon dioxide, followed by pushing the carbon dioxide rim with the injected water, characterized in that the acid is first pumped solution, which is used as a composition DN-9010 - an aqueous solution of hydrochloric acid, lignosulfonate, solvent and nonionic surface-act vnogo substance or nonionic surfactant SNPCH-9021 - aqueous solution of hydrochloric acid and / or hydrofluoric acid, solvent and nonionic surfactant, or a composition comprising, in weight%:. Hydrochloric acid  10.0-25.0 Nonionic surfactants  0.05-1.0 Water  Rest and then a polymer-alkaline solution, including, wt.%: Water soluble carbonic acid salt  5.0-15.0 Water soluble polymer  0.05-1.0 Water  Rest