RU1792483C - Method for declaying the bottomhole formation zone - Google Patents

Description

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The invention relates to the oil and water industry, in particular to the volume of chemical exposure to the near-field zone.

The most common formulations for chemical exposure

various acid solutions with

surfactant eavacs

lavic acid 1.

Closest to the proposed drilling is a method of acid working wells, including injection into

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He believes that a substance with a viable dissolution temperature is introduced into the solution in order to lower its temperature.

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This method can be used in tenge in carbonate reservoirs, since a high content of hydrochloric acid in combination with a substance having a positive dissolution temperature in an aqueous medium causes inhibition of clay particles and prevents them from being emitted from the pore space of the reservoir.

In order to increase the production rate of the product from the well, it is necessary that the pore space of the reservoir does not contain clay particles that enter it either during sedimentation or from the drilling fluid during drilling of the well. At the same time, water entering the pore space containing clay particles causes dispersion and peptization of the latter, which sharply affects the reservoir properties of the formation.

The purpose of the invention is to increase the efficiency of claying of the bottomhole formation zone by destroying clay particles present in the pore space of the formation. An additional object of the invention is to reduce the consumption of salt

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acid, increase, if necessary, the density of the solution m decrease the time of wedging.

The goal is achieved by the fact that in the solution of hydrochloric acid with a concentration of 1-5%, an ammonium-containing substance from 5 to 50% is introduced and the solution is heated at temperatures from 50 ° C to boiling point. I ...;;. „. ,. . -. ... .

The essence of the invention consists in the following, ammonia ions formed during dissociation of an ammonium-containing substance at a solution temperature of 50 ° C or higher affect an aluminum atom located in the center of the crystal lattice of a clay particle, and structural bonds are weakened therein. Hydrogen ions formed during the dissociation of hydrochloric acid finally destroy the structure of clay formation. Gases formed during the reaction also contribute to the destruction and dispersion of particles.

In order to verify the effectiveness of this method, laboratory tests were carried out to determine the time of destruction of samples at different concentrations of reagents and at different temperatures. A solution of hydrochloric acid with a concentration of 0.5-10%, heated from 20 ° C to the boiling point of the solution, with the addition of carbamide, ammonium nitrate and ammonium chloride in an amount of 1-500 g per 1 liter of solution, spherical clay samples with a diameter of 20 mm were processed and weighing 10 g. The time of destruction of the sample was recorded with an accuracy of ± 0.5 min. Fig. 1 shows the dependence of the time of sample destruction on the concentration of hydrochloric acid at a constant temperature and the concentration of an ammonium-containing substance; in FIG. 2 - dependence of the sample destruction time on the concentration of ammonium-containing substance at constant temperatures and the concentration of hydrochloric acid; in FIG. 3 - dependence of the paspVuieHHfl time of the sample on the solution temperature at constant concentrations of hydrochloric acid and ammonium-containing substance.

When implementing this method, an aqueous solution of hydrochloric acid and a powdered ammonium-containing substance (or its aqueous solution) are used, for example: urea, ammonium nitrate, ammonium chloride, etc. A solution is prepared immediately before use on

well. The required volume of water for preparing the solution is determined on the basis of 0.4 -1m3 of solution per 1 running. m. of the treated area. If the formation temperature is below 50 ° C, then the water is heated to a temperature depending on the formation. At reservoir temperatures up to 20 ° C, the water is heated to boiling, in the temperature range 20 - 30 ° C - up to 60 - 80 ° C, in the range

at temperatures of 30-50 ° C, the water is heated to 50-60 ° C. At reservoir temperatures above 50 ° C, the solution is heated directly in the well. Hydrochloric acid is introduced into the water to obtain a total concentration

solution of 1 - 5%. At the same time as hydrochloric acid, an ammonium-containing reagent is introduced into the solution in an amount of 50-500 kg per 1 m3 of solution.

The method is carried out as follows. After the solution is prepared, it is pumped into the treatment zone and squeezed into the formation with a depression of 1.5 - 4.0 MPa, maintained for 3 to 4 hours and then the pressure is sharply relieved, after which

well development is carried out by traditional methods,

When implementing this method, the consumption of hydrochloric acid is more than halved; if necessary, the density of the solution can be increased without changing its technological properties to 1150 kg / m3. With an increase in the temperature of the solution from 50 ° C and above, the reaction rate for the destruction of clay particles and the time sharply increase.

well development is reduced from 16 - 20 hours with basic technologies to 3 - 4 hours according to the proposed.,

Claims (1)

SUMMARY OF THE INVENTION A method for wedging the bottom of a formation, comprising injecting a solution of hydrochloric acid, ammonium-containing material and water into the formation, characterized in that, in order to increase the efficiency of wining of the bottom of the formation, to reduce the consumption of hydrochloric acid, increase the density of the solution and reduce the time of wedging, Before injection into the formation, the solution is heated at temperatures from 50 ° C to the boiling point, while the solution contains components in the following ratio, May. %: Solution of hydrochloric acid 1-5 Ammonium-containing substance 5-50. Water Else 1  AND I Щ® t  th Ifi "S I feI a 05 12 5 h 5 y innnt spawn will destroy- sample, pin.  . % 2 2 , 90 t “I; a I | , S b- 50 "  hell I 2 3 H 5 6 7 B / w / destruction. , 9 SE II / 2/5 14 soup, pin