RU2268360C1 - Well bottom zone treatment method - Google Patents

Abstract

FIELD: oil industry, particularly methods for stimulating oil production.

SUBSTANCE: method involves killing well with the use of aqueous emulsifier solution; forcing acid solution in productive formation zone with light-weight oil at rate of 24-35 m³/day and under 0.8 - 1.5 MPa pressure at tubing string head; performing technological time delay for not less than 3 hours and performing well bottom depression by swabbing thereof up to obtaining pressure of not less than 3 MPa and pH value of 6-7; lowering pumping equipment and developing well.

EFFECT: increased efficiency of well bottom zone treatment.

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Description

The present invention relates to the oil industry and may find application in the stimulation treatment of the bottomhole zone of the well.

A known method of processing the bottom-hole zone of a well, which includes injecting acid into the formation (Sh.K. Gimatudinov. Oil production reference book. M: Nedra, 1974, p. 420-432).

The known method allows to increase the permeability of the bottom-hole zone, however, the effectiveness of the method is low due to secondary colmatation of the bottom-hole zone by reaction products.

Closest to the proposed invention in technical essence is a method of processing the bottom-hole zone of a well, which includes injecting an acid solution into the zone of a productive formation, carrying out technological exposure and extracting the spent chemical reagent by creating depression (RF Patent No. 2140531, publ. 10.27.1999 - prototype).

The known method allows you to extract due to depression from the bottom zone of the reaction products and to a large extent to avoid secondary colmatation of the bottom zone of the reaction products, however, the effectiveness of the method remains low.

The proposed invention solves the problem of increasing the efficiency of cleaning the bottom-hole zone of the well.

The problem is solved in that in the method for treating the bottom-hole zone of a well, which includes injecting an acid solution into a zone of a productive formation, technological exposure and depressing effect, according to the invention, the well is first pre-killed by an aqueous emulsifier solution, and the acid solution is injected into a zone of a productive formation by light oil at a rate of 24 -35 m ³ / day and at a pressure in the mouth on a column of tubing 0.8-1.5 MPa exposure process is carried out not more than 3 hours, the depression effect perform swabbing to depression downhole not lower than 3 MPa and the hydrogen to achieve pH in the range 6-7, and then drained pumps and master hole.

The features of the invention are:

1. selling acid solution into the zone of the reservoir;

2. technological exposure;

3. depressive effects;

4. preliminary killing of the well with an aqueous emulsifier solution;

5. injection of acid solution into the productive formation zone with light oil at a flow rate of 24-35 m ³ / day and at a pressure at the mouth of the tubing string of 0.8-1.5 MPa;

6. technological exposure no more than 3 hours;

7. Depression effect by swabbing to depression at the bottom of the well not lower than 3 MPa;

8. the same until a pH of 6 to 7 is reached;

9. descent of pumping equipment and well development.

Signs 1-3 are common with the prototype, signs 4-9 are the salient features of the invention.

SUMMARY OF THE INVENTION

During the operation of oil producing wells, deposits of mudding elements occur, which reduce the permeability of the bottomhole zone and, as a result, reduce the productivity of the wells. The traditionally used technology for treating the bottom-hole zone with a solution of hydrochloric acid leads to a minimal effect. Even a technology with a combination of hydrochloric acid treatment and depressive effects has low success and effectiveness. The proposed invention solves the problem of increasing the efficiency of processing the bottom-hole zone of the well due to its more complete cleaning from clogging deposits. The problem is solved as follows.

When processing the bottom-hole zone of the well, killing the well is carried out with an aqueous emulsifier solution. As an emulsifier use an emulsifier Ringo-EM according to TU 2413-003-52412574-01. The Ringo-EM emulsifier is a 40% solution of complex esters of higher unsaturated fatty acids (linoleic, oleic, linolenic, etc.) and resin acids in diesel fuel with the addition of an organosilicon stabilizer, 2% alkyldimethylamine oxide and a nonionic surfactant. In appearance, the Ringo-EM emulsifier is an oily viscous liquid from light brown to black. The emulsifier Ringo-EM has an acid number in the range from 2 to 4 mg KOH / g and the pour point is not higher than minus 35 ° C. When a Ringo-EM emulsifier is mixed with mineralized water, an increased viscosity liquid is formed. Silencing a well with such a composition helps to eliminate the negative effect of killing water on the reservoir properties of the bottomhole zone. Well production is not reduced. To ensure the necessary viscosity properties, the ratio of emulsifier and water in the range of 2-10: 90-98 (by weight) is optimal.

Through the tubing string, an acid solution is pushed into the productive formation zone with light oil at a rate of 24-35 m ³ / day and at a wellhead pressure of 0.8-1.5 MPa on the tubing string. Such a low flow rate and low pressure facilitates the flow of an acid solution even into an initially non-receiving well. When part of the acid solution enters the bottom-hole zone, the flow rate and pressure are increased as much as possible, avoiding a decrease in injectivity.

Technological exposure is carried out for no more than 3 hours. During this time, the acid manages to react with the carbonate component of the reservoir and increase the permeability of the bottomhole zone. Exposure for more than 3 hours contributes to the formation of mudding deposits, which reduce the permeability of the bottomhole zone and minimize the effect of acid treatment.

As an acid solution, a 6-15% aqueous hydrochloric acid solution is used.

Depression effect is performed by swabbing the plunger along the tubing string until depression at the bottom of the well is at least 3 MPa and until the pH reaches a pH value of 6-7. By swabbing, the reaction products are removed from the bottomhole zone. Restrictions on downhole depression are due to oil degassing pressure, below which downhole pressure cannot be reduced. When swabbing, the pH of the liquid is determined. As a rule, it decreases from 2-3 at the beginning to 6-7 at the end of swabbing. According to the pH of the swab fluid, a pH within 6-7 judges the removal of acid from the bottomhole zone and the well and the possibility of completing swabbing. After that, the pumping equipment is lowered and the well is mastered.

Concrete example

Bottom-hole treatment of an oil well is carried out. Well depth 1200 m. Casing string diameter 146 mm. The interval of the productive carbonate formation is located at depths of 1171-1193 m. The well is equipped with a tubing string with a diameter of 73 mm. The wells are jammed with an aqueous solution of Ringo-EM emulsifier in the following ratio of components, parts by weight: emulsifier: water = 7:93. Through the tubing string, a 12% hydrochloric acid solution is pushed into the productive formation zone with light oil at a rate of 30 m ³ / day and at a mouth pressure of 1 MPa in the tubing string. Technological exposure is carried out for 3 hours. Depression is performed by swabbing the plunger along the tubing string until depression at the bottom of the well is not lower than 3 MPa and until the pH reaches a pH value of 6.5. After that, the pumping equipment is lowered and the well is mastered.

As a result, the flow rate of the well increased from 1.1 to 12 m ³ / day. The treatment of the bottom-hole zone according to the prototype in similar conditions leads to the effect of up to half of the achieved.

Claims (1)

A method of treating a bottom-hole zone of a well, which includes injecting an acid solution into a zone of a productive formation, technological exposure and a depressing effect, characterized in that the wells are pre-milled with an aqueous emulsifier solution, and an acid solution is injected into the zone of a producing formation with light oil at a flow rate of 24-35 m ³ / day and when the pressure at the wellhead on the tubing string is 0.8-1.5 MPa, the technological exposure is carried out for no more than 3 hours, the depressive effect is performed by swabbing until depression at the bottom of the well not lower than 3 MPa and until the pH reaches a pH of 6 -7, after which the pumping equipment is lowered and the well is mastered.