RU1795083C - Plugging-back solution - Google Patents

Abstract

SUMMARY OF THE INVENTION: the solution contains components, wt.h .: grouting cement 100; self-scattering aluminum slag - waste from the production of high alloy aluminum 1-6; polyvalent metal salt of 0.5-10.0; water 45-100. The waste contains free aluminum, in the reaction of which hydrogen is generated with calcium hydroxide. Copper sulfate, iron sulfate, etc. are used as the salt. The dry mixture of the components is closed on an aqueous solution of salt. The solution has a high sedimentation and suffosion stability. 2 tab.

Description

The invention relates to deep drilling, in particular, cement slurries intended for cementing casing strings in oil and gas, geothermal and special wells under conditions of oil and gas flow and high temperatures.

Well cementing slurries for cementing wells prepared by incorporating calcium oxide into the cement slurry are known. These grouting mortars have a slightly increased, compared to non-additive, plugging ability, due to the expansion of the structure of the cement mortar.

The disadvantage of these grouting solutions is accelerated hardening under conditions of moderate temperatures and the associated intense drop in pore pressure of grouting slurry. In addition, intensive hydration of a portion of the calcium oxide at elevated temperatures and its conversion to calcium hydroxide prior to the start of the structure formation process does not cause the expansion of the grout.

Thixotropic cement mortars are also known containing cement, water, a titanium complexing compound, and a cross-linked water-soluble resin. These grouting compositions have improved insulating characteristics (plugging ability) compared to the well-known grouting mortar.

However, these grouting compositions are also subject to a decrease in pore pressure during the hardening process, and the required value of the static shear stress (240 Pa), at which the formation fluid does not begin to migrate to the tampon. achieved after a considerable time after the end of the cement mortar and the space is riveted, and the probability is f / iCli-.

Xi

U 01

about

00

with

the skeleton of the cement slurry with high-pressure formation fluid is known to be higher in the initial period of hardening of the cement slurry.

The closest to the proposed technical solution in terms of technical nature and the achieved result is cement slurry including, maeh,:

Grouting cement 64.6. Water 32.3. Water glass 1.55 Sodium chloride 1.29 Aluminum powder 0.13 This cement composition is capable of expanding due to hydrogen evolution. Its disadvantage is that the gas evolution process is accompanied by a sharp loss of mobility, which makes it impossible to use it for fastening wells under conditions of elevated and high temperatures.

The purpose of the invention is to preserve the initial feather pressure during the period of formation of the grout during grout during high and high temperatures, as well as to increase its tamping ability.

This goal is achieved in that the tempering solution contains self-scattering aluminum slag (SRPC) formed during the smelting of highly alloyed aluminum, and as an additive, a gel-forming salt of polyvalent 1 metal in the following ratio of components, wt.h .:

Grouting cement 100. Self-scattering

aluminum slag (SRCH) 1-6 Polyvalent metal salt 0.5-10 Water 45-100 Grouting Portland cement, slag cement, and various grouting mixtures based on these cements are used as grouting material.

As an aluminum-containing component, self-scattering aluminum slag (SRPC) is used, which is formed during the smelting of high-alloyed aluminum grade AK21MZN at a temperature of 680-900 ° C. During cooling of the melt in the air, a dark gray slag of sufficiently high dispersion is formed. In case of violation of the melting technology, lumpy metal aluminum forms in the slag, which is easily subjected to crushing and grinding to the required size.

The average chemical composition of SRSH is as follows, wt.%:

A 20z50.03

CaO3.73 SI02 16.95

MnO0.109

P.P.P. 9.24

A1 „e26.5

MdO 9.21 KZO 7.15

NaaO, 5.94

P20s0,135

The density of SRSH ranges from 2380-2500 kg / m3.

5 Chlorides, sulfates, nitrates of iron, zinc, and copper are used as the salt of the polyvalent metal. They form insoluble gel systems in the viscoelastic pores of the cement slurry during the chemical reaction with calcium hydroxide released during the hydrolysis and hydration of minerals in cement cement.

The combined use of these components within the scope of the claims 5 contributes to the achievement of the objectives of the invention. The following mechanism of action of the proposed additives is proposed.

The long-term maintenance of the pore pressure 0 and the increase in the tamping ability of the cement slurry in the annular space during the period 03C is achieved due to the gaseous component formed upon exposure to calcium hydroxide and calcium with the aluminum part of CPPP, the total reaction of which can be represented as follows:

2AI + 3Ca (OH) 2 + 6H20 -

- (OH) b 2 + 3H2 I

0 Calcium hydroxoaluminate (OH) formed in the pore space of a cement slurry is a sparingly soluble gel which is stable in an alkaline environment. Due to the colmatization of the threshold 5 space in the viscoelastic gel of calcium hydroxoaluminate, the filtration characteristics of the grouting slurry are reduced, thereby increasing the tamping capacity coefficient. 0 In addition, a significant increase. plugging ability occurs due to volume expansion of the structure of the grouting test as a result of hydration of the magnesium oxide contained in SRPC. 5 This effect is especially noticeable at high temperatures.

The role of the salt additive is to impart the viscoelastic, thixotropic properties of the grouting slurry in order to self-heal the channels formed

upon evolution of a gaseous agent. In addition, additives of polyvalent metal salts regulate the rate of thickening and setting of grouting suspensions, i.e. adjust the start time of the CPRCH reaction with the cement hydration components,

The results of comparative tests are presented in table. 1 and 2.

The preparation of grouting mortar is carried out as follows.

Example. It is required to prepare a cement slurry from PCT-D50-100 with increased sedimentation and suffusion resistance (increased plugging coefficient) for cementing a well with a bottomhole temperature of 90 ° C, and 5. Curing time of the solution for at least 2 hours 40 minutes. For the preparation of said grouting mortar, 100 m.h. cement cement is mixed with 4 wt.h. SRASH until complete homogenization of the mixture. The resulting mixture was closed on a liquid into which 1.5 parts by weight were previously added. copper sulphate at 5.

In a similar manner, grout formulations are prepared with other cement materials and additives for various cementing conditions.

The composition and properties are given in table. 1 and 2, respectively.

The limits of the content of SRSP and gel-forming components (salts of polyvalent metals) are selected from the following considerations. When the content of these components is less than 1 and 0.5 wt.h. accordingly, a decrease in initial feather pressure is observed, and the plugging ability is small. With an increase in the content of components of more than 10 and 10 parts by weight, the technological properties of the cement slurry (flowability, rheological properties, etc.) deteriorate, and the coefficient of the plugging ability remains practically unchanged.

The composition of the developed grouting mortar is selected in such a way that allows to maintain and maintain the initial pore pressure in the OZC process until the formation of a strong structure of the cement slurry is completed. In addition, the gas evolution that begins after the cement slurry is pushed into the annulus prevents the occurrence of suffusion channels formed by the action of the filtration flows due to a decrease in the peroral pressure. The polyvalent metal salt contained in the grouting mortar, as a result of interaction with the cement, forms a viscoelastic, thixotropic gel, which gives it the ability to self-heal suffusion channels, if for some reason they are formed,

All of the above contributes to an increase in the insulating characteristics of the cement slurry (sedimentation and suffusion stability, the coefficient of plugging ability).

The use of the developed grouting mortar will improve the quality of well fixing and increase the well overhaul period.

Claims (1)

SUMMARY OF THE INVENTION A grouting mortar comprising grouting cement, an aluminum-containing component, an additive, and water, characterized in that, in order to maintain the porous pressure during the period of formation of the mortar and hardening of the stones while increasing the tamping ability, it contains as an aluminum-containing component self-scattering aluminum slag is a waste product of high-alloyed aluminum, and as an additive it is a salt of a polyvalent metal in the following ratio of components, parts by weight: Grouting cement 100 Self-scattering aluminum slag - waste from the production of high-alloyed aluminum 1-6 Polyvalent metal salt 0.5-10.0 Water 45-100 Note. Coefficient of plugging ability and relative nopotoe pressure were determined by the Soloviev-Guerenim method. Table 1 Table 2 .