RU2485285C1 - Preparation method of backfill compound for repair insulation work - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: preparation method of backfill compound for repair insulation work involves mixing of acetone-formaldehyde resin with caustic soda and water. At that, there preliminarily prepared is water solution of caustic soda by mixing the latter with water; water solution of caustic soda is divided into two equal portions; the first portion of water solution of caustic soda is introduced to acetone-formaldehyde resin; the obtained mixture is mixed till indiscrete mass is obtained and exposed for 60-120 minutes. While mixing, the second portion of water solution of caustic soda is introduced at the following reagent ratio, wt %: acetone-formaldehyde resin 80-95, caustic soda 1-2, water is the rest.

EFFECT: improving efficiency and quality of repair insulation work owing to controlling curing periods of backfill compound at simultaneous reduction of influence of exothermic effect of reaction at its preparation; increasing strength of cured backfill compound.

5 ex, 1 tbl

Description

The invention relates to the oil and gas industry and is intended for the preparation of grouting composition for repair and insulation works in oil and gas wells.

A known method of isolating and restricting water inflow into wells, including injecting into the well an insulating material containing urea-formaldehyde or acetone-formaldehyde resin, a polymerization initiator, a filler, an additive, water, pushing it and holding it for the time of curing and curing, the insulating material additionally contains ethoxylated isononylphenols, hydroxyethylated monoalkylphenols or a mixture thereof, natural or synthetic rubber, or a mixture thereof. Injection and sale of this material is carried out cyclically (patent RU No. 2349731, IPC E21B 33/13, C09K 8/512, publ. 08.27.2003, bull. No. 24).

This method has several disadvantages. It is technologically difficult to prepare the insulation composition at the place of work due to its multicomponent nature, which requires a large amount of machinery and equipment. In addition, the effectiveness of insulating work is reduced during cyclic injection of the insulating composition and squeezing liquid, because dilution of the insulating composition with squeezing liquid is not excluded, as a result, the initial concentration of the insulating material is violated, the yield of the polycondensation product is reduced, and the curing time is increased.

The closest technical solution to the proposed proposal is a polymer composition for isolating water inflow and absorption zones in the well, containing acetone-formaldehyde resin, alkaline hardener, urea, water. The polymer composition is prepared as follows: urea is introduced into the acetone-formaldehyde resin, heated to 50-60 ° C, after cooling, water and an alkaline hardener are introduced. The composition is stirred for 15 minutes (a.s. No. 1040121, IPC E21B 33/138, publ. 09/07/1983, bull. No. 33).

The disadvantage of this method is the difficulty of regulating the curing time of the cement composition due to the high exothermicity of the curing process of the composition, because when alkaline hardener is added to the resin, a sharp increase in temperature (up to 70 ° C) of the reaction mass of the grouting composition occurs, which, in turn, leads to a rapid increase in the rheological parameters of the composition to technologically unacceptable for the use of the grouting composition for its intended purpose (during preparation, injection and pushing into the well), to the low strength properties of the resulting cement stone. In addition, when preparing the composition, it is necessary to heat the acetone-formaldehyde resin to 50-60 ° C, which leads to a number of difficulties in preparing the composition in the field.

The technical objectives of the proposal are to increase the efficiency and quality of repair and insulation works by adjusting the curing time of the grouting composition while reducing the influence of the exothermic effect of the preparation, and increasing the strength of the cured grouting material.

The technical problem is solved by the proposed method for the preparation of grouting composition for repair and insulation works, including mixing acetone-formaldehyde resin with caustic soda and water.

It is new that an aqueous solution of caustic soda is prepared beforehand by mixing caustic soda with water, the aqueous solution of caustic soda is divided into two equal portions, the first portion of the aqueous solution of caustic soda is introduced into the acetone-formaldehyde resin, the resulting mixture is stirred until a homogeneous mass is held for 60- 120 min, then with stirring, a second portion of an aqueous solution of sodium hydroxide is introduced in the following ratio of reactants,% wt .:

acetone formaldehyde resin 80-95 sodium hydroxide 1-2 water rest.

Acetone-formaldehyde resin is a light to brown homogeneous liquid according to TU 2228-006-48090685-2002.

Technical caustic soda according to GOST 2263-79.

Water with a density of 1000 kg / m ³ .

A method of preparing the proposed grouting composition in the field is as follows: in advance using standard equipment for the overhaul of wells (with a mixing device), an aqueous solution of caustic soda is prepared, for this caustic soda is mixed with water; divide an aqueous solution of caustic soda into two equal portions; then, to the acetone-formaldehyde resin using mixing devices, a first portion of an aqueous solution of sodium hydroxide is introduced; the mixture is thoroughly mixed until a homogeneous mass; then the mixture can withstand 60-120 minutes; then a second portion of an aqueous solution of sodium hydroxide is introduced with stirring; then the mixture is thoroughly mixed until a homogeneous mass; after mixing, the grouting composition is pumped into the well.

The curing of acetone-formaldehyde resin is accompanied by heat (exothermic reaction). The introduction into the acetone-formaldehyde resin of an aqueous solution of sodium hydroxide in portions (in two portions) in equal amounts, exposure to the mixture after introducing the first portion of an aqueous solution of sodium hydroxide can reduce the effect of the exothermic effect of the reaction and obtain a cement stone for the technologically necessary time for repair and insulation works and , therefore, to exclude emergencies in the preparation, injection and sale of grouting composition. Reducing the exposure time of the mixture less than 60 minutes does not reduce the influence of the exothermic effect of the reaction, and with increasing exposure time of the mixture more than 120 minutes it is impractical from an economic point of view due to the increase in the cost of repair work.

Studies of the proposed method for the preparation of grouting composition for repair and insulation work is carried out in laboratory conditions with the following ratio of reagents,% wt .:

acetone formaldehyde resin 80-95 sodium hydroxide 1-2 water rest.

An example of a specific implementation 1.

An aqueous solution of caustic soda is prepared in advance by diluting caustic soda with 2% wt. in water with a density of 1000 kg / m ³ 18% wt. Divide the aqueous solution of caustic soda in two equal portions.

Then to acetone-formaldehyde resin 80% wt. enter the first portion of an aqueous solution of caustic soda (caustic soda 1% wt., water 9% wt.). The mixture is thoroughly mixed until a homogeneous mass for 10 minutes and incubated for 120 minutes Then, a second portion of an aqueous solution of caustic soda (caustic soda 1% wt., Water 9% wt.) Is introduced with stirring and mixed until a homogeneous mass for 10 minutes

The curing time of the composition is determined visually. The prepared grouting composition is placed in a glass cup according to the above sequence. The glass is kept in a thermostat. The time from the start of introducing a second portion of an aqueous solution of sodium hydroxide into the reaction mixture of cement composition is noted. By periodically tilting the glass, the time is fixed when the meniscus of the grouting composition ceases to shift. The time thus determined is the curing time of the test cement composition. Cure time is defined as the arithmetic average of three measurements. The results of laboratory tests are shown in the table.

To determine the effectiveness of the method of preparing the grouting composition in laboratory conditions, measure the temperature of the reaction mixture in time, since the curing process of the grouting composition is accompanied by heat. With an increase in the temperature of the grouting composition, curing times are reduced. The starting point is the moment of introduction into the acetone-formaldehyde resin of the first portion of an aqueous solution of sodium hydroxide.

Example 2 is produced analogously to example 1. The exposure time of the mixture is 60 minutes.

Examples 3-5 produce analogously to example 1.

Strength characteristics of obtained cement stones are determined according to GOST 26798.1-96.

Table No.
p / p The grouting composition,% wt. temperature tamp. composition, ° C Curing time depending on the volume of the prepared cement composition, h-min Compressive strength, MPa, after 28 days Shrink after 28 days aceto-nofor-malde-hydro resin sodium hydroxide water urea after 15 min after 60 min 500 cm ³ 2000 cm ³ one 80 2.0 18.0 - 23.6 31,0 2-30 2-10 15.43 Shrinkage not
is watching
sya 2 85 2.0 13.0 - 25.0 29.0 1-30 1-15 16.52 3 85 one 14.0 - 22.1 24.4 7-00 6-45 12.21 four 90 1,5 8.5 - 24.4 28.5 2-00 1-40 15,56 5 95 1,0 4.0 - 22.5 25,2 5-50 5-20 13.74 prototype 6 55 one 38 6 35 * 45.2 * 2-15 * 0-55 * 0.89 * Shrinkage not
observed 7 67 0.3 26.7 6 29 * 37.1 * 2-40 * 1-10 * 3.02 * 8 80 one 13 6 57 * - 0-30 * 0-05 * 8.87 *

Note: Values with a dash (*) are defined by the applicant.

The table shows that the preparation of the grouting composition in the proposed sequence allows you to get the grouting composition with an adjustable curing time from 1 h 15 min to 6 h 45 min. The batch introduction of an aqueous solution of caustic soda into an acetone-formaldehyde resin leads to a monotonous (gradual) rise in the temperature of the grouting composition in comparison with the grouting composition prepared according to the prototype, which makes it possible to prepare the grouting composition within a technologically necessary time, pump it and push it into the well. In addition, a slight change in the curing time of the grouting composition with increasing volume (from 500 cm ³ to 2000 cm ³ ) of the grouting composition being prepared indicates a decrease in the influence of the exothermic effect of the reaction.

The content in the grouting composition of acetone-formaldehyde resin in an amount of 80-95% wt. compared with the grouting composition prepared according to the prototype, leads to the formation of a more durable grouting stone. The compressive strength after 28 days of storage of the cured samples in produced water was 12.21 ÷ 16.52 MPa compared with the prototype 0.89 ÷ 8.87 MPa. The study of cement stones obtained during their long-term storage in produced water showed that their size did not change, i.e. no shrinkage.

Thus, in this proposal, the result is achieved - increasing the efficiency and quality of repair and insulation works by adjusting the curing time of the cement slurry while reducing the influence of the exothermic effect of the reaction during preparation and increasing the strength of the cured grouting material.

Claims (1)

A method of preparing a grouting composition for repair and insulation works, comprising mixing acetone-formaldehyde resin with caustic soda and water, characterized in that the aqueous solution of caustic soda is prepared by mixing caustic soda with water, the aqueous solution of caustic soda is divided into two equal portions, introduced into acetone-formaldehyde resin, the first portion of an aqueous solution of caustic soda, mix the resulting mixture until a homogeneous mass, incubated for 60-120 minutes, then with stirring, inject a second portion of aqueous p sodium hydroxide solution in the following ratio of reactants, wt.%:
acetone formaldehyde resin 80-95 sodium hydroxide 1-2 water rest