RU2597907C1 - Method of producing grouting composition for waterproofing structure in rocks of water-soluble salts - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining, specifically to methods of producing grouting compositions for waterproofing structures in rocks of water-soluble salts. Method of producing grouting composition for waterproofing structure in rocks of water-soluble salts involves preparation of a mixture containing an aqueous solution of polyacrylamide and a cross-linking agent, in mixture is prepared using a concentrated aqueous solution of low-molecular weight of polyacrylamide, prior to addition of a cross-linking agent, saturated salt solution is added, in which there is a waterproofing structure, and in addition salt of same composition in an amount required for saturation of aqueous solution of polyacrylamide. Volume of added salt solution is defined by required viscosity of grouting composition. Salts for saturation of aqueous solution of polyacrylamide are added in milled form.

EFFECT: technical result is preparing a grouting composition, improving reliability of waterproofing of underground structures in conditions of water-soluble salts by waterproofing surface of structure in a wide range of controlled time, temperature and degree of water mineralisation.

1 cl, 2 tbl

Description

The invention relates to the mining industry, and in particular to methods for producing grouting compositions for waterproofing structures in rocks of water-soluble salts.

A known method for producing hydrolyzed polyacrylamide (GPAA) for gel-forming compositions, comprising preparing a reaction mixture containing an aqueous solution of acrylamide and alkali metal salts of carbonic acid, deoxygenation, polymerization of acrylamide with combined hydrolysis by heating the reaction mixture under the action of radical initiators, before deoxygenation is prepared the mixture is kept for 2-4 hours at a temperature of 25-40 ° C (Pat. 2175975 Russian Federation, IPC ⁷ C08L 101/14, E21 In 43/22, C08F 220/56, C08F 220/04. A method of producing hydrolyzed polyacrylamide for gel-forming compositions - Z. No.2000106083/04, declared 13.03.2000, publ. 20.11.2001, bull. No. 32).

The disadvantage of this method is that it does not provide the reliability of plugging in water-soluble rocks.

Closest to the proposed technical solution is a viscoelastic composition for insulation work in wells, including polyacrylamide (PAA), a crosslinker, hydrochloric acid, a filler and water, which contains urotropine or formalin as a crosslinker, and lignin or softwood flour as a filler (Pat. 2147672 Russian Federation, IPC ⁷ Е21В 33/138, Е21В 43/32. Viscoelastic composition for insulation work in wells. - Z. No. 98119387/03, decl. 10.26.1998, publ. 04.20.2000).

The disadvantage of this composition is that after plugging the gaps during crosslinking, an aqueous solution of polyacrylamide will dissolve the salts with which it comes into contact, resulting in the formation of new voids (gaps) and the goal of plugging, namely the complete filling of voids and gaps will not be achieved.

The technical result of the invention is to obtain a grouting composition that increases the reliability of waterproofing of underground structures in rocks of water-soluble salts by waterproofing the surface of the structure in a wide range of adjustable time, temperature and degree of mineralization of water.

The specified technical result is achieved by the fact that in the method of producing a cement slurry for waterproofing structures in water-soluble rocks, comprising preparing a mixture containing an aqueous solution of polyacrylamide and a crosslinking agent, a concentrated aqueous solution of low molecular weight polyacrylamide is used to prepare the mixture, and a saturated solution is introduced before adding the crosslinking agent salts in which the waterproofing structure is located, and additionally salts of the same composition in quantity, is necessary ohm to saturate the aqueous solution of polyacrylamide.

The volume of injected salt solution is determined by the required working viscosity of the cement composition. Salts to saturate an aqueous solution of low molecular weight polyacrylamide are added in crushed form.

In underground mines, the need for waterproofing works periodically arises. For the waterproofing of underground structures in conditions of water-soluble rocks (salt, potash mines), in particular in the conditions of potassium-magnesium salts, it is necessary to have a waterproofing composition that swells in aqueous solutions of low molecular weight hydrogel electrolytes in combination with resistance to salt.

To ensure a selective change in the water permeability of underground structures, the surface of underground structures is sealed using materials whose particles, after entering the reservoir, increase their geometrical dimensions and are firmly held due to this in the rock. At the same time, an insulating screen of a sealed gel-like polymer layer of the required volume is formed on the surface of the reservoir or underground structure depending on the permeability of the rock surface. The required gelation rate is achieved by changing the concentration of the polymer dispersion, the size of the polymer particles and their swelling rate in water.

The implementation of the proposed method is given for the conditions of the Verkhnekamsk deposit of potassium and magnesium salts.

The plugging of the waterproofing structure in the sylvinite reservoir, consisting of NaCl (71%) and KCl (29%) salts, was carried out in the following sequence.

Initially determine the time spent on grouting. The required tamping time is at least 20 hours. It was accepted with a margin that gelation time should be 25-28 hours.

The following composition of 1 m ^{3 of} grouting composition with the required gelation time was experimentally established.

An aqueous solution of 31% polyacrylamide (PAA) - 510 liters.

The solution saturated with NaCl and KCl is 398 l.

A finely divided mixture of salts of NaCl (71%) + KCl (29%) - 137 kg.

37% formalin solution - 25.5 liters.

The grouting composition was prepared in the following sequence.

Formalin was mixed with a solution of NaCl + KCl, after stirring, an aqueous solution of 31% PAA and a finely divided mixture of salts of NaCl + KCl were added to it and stirred for 10-15 minutes.

The efficiency of using acrylamide polymers in gel-forming compositions was evaluated by gelation time and dynamic viscosity values of the compositions.

Concentrated aqueous solutions of acrylamide polymers were tested at temperatures from 10 to 50 ° C in aqueous gelling formulations containing crosslinking agents.

Examples.

The effectiveness of the proposed structure for waterproofing structures in rocks, water-soluble salts, having the form of a gel, is confirmed by the results of laboratory tests.

The dependences of the gelation time on the parameters of aqueous gelling compositions were determined: the concentration of PAA, GPAA and crosslinking agents, the pH of the initial aqueous solutions of PAA, water salinity and gelation temperature.

17 gels of various compositions (Table 1) were subjected to laboratory tests upon their contact with water and dissolution of salts.

The tests were carried out as follows.

Crosslinked gel samples with an initial volume of 80 ml were placed in a vessel and 300 ml of liquids of various compositions were poured into it. At certain intervals, the liquid was poured, its volume was determined and again poured into the vessel. The experimental results are shown in table 2.

From table 2 it follows that the gels prepared on water in contact with a salt solution decrease in volume, which does not provide sealing, and the gels prepared on a salt solution with the addition of salt powder increase in volume, which ensures reliable sealing of plugging of salt rock.

In addition, laboratory tests found that the gelation time of an aqueous solution of PAA increases:

- with a decrease in temperature (from 50 to 10 degrees - 10-20 times);

- with a decrease in the concentration of PAA (from 20 to 5% - 10-20 times);

- a decrease in the concentration of formalin (from 3.5 to 1% - 10 times);

- increasing the pH-gelling water composition (from 3 to 10 - 10 times);

- increase the salinity of the aqueous gelling composition (in the presence of sodium chloride with a mass concentration of 15% - 2 times);

- increase in the intrinsic viscosity of PAA (from 1.4 to 0.4 dl / g - 4-8 times).

To obtain a form-stable polymer gel within 24 hours at 10 ° C, it is necessary to use a gel-forming composition with a high degree of mineralization and with a pH of less than 6, containing 1.7% of the mass. formalin and 20% of the mass. polyacrylamide having an intrinsic viscosity of less than 0.5 dl / g.

Using the proposed technical solution allows to obtain a waterproofing composition that ensures the reliability of the waterproofing of underground structures in rocks of water-soluble salts due to the waterproofing of the surface of the structure in a wide range of adjustable time, temperature and degree of mineralization of water.

Claims (2)

1. A method of producing a grouting composition for waterproofing a structure in water-soluble salts, comprising preparing a mixture containing an aqueous solution of polyacrylamide and a crosslinking agent, characterized in that a concentrated aqueous solution of low molecular weight polyacrylamide is used to prepare the mixture, and a saturated salt solution is added before adding the crosslinking agent, in which there is a waterproofing structure, and additionally salts of the same composition in the amount necessary to saturate the aqueous solution and polyacrylamide, while salts for saturation of an aqueous solution of low molecular weight polyacrylamide are added in powdered form. 2. The method according to p. 1, characterized in that the volume of the injected salt solution is determined by the required working viscosity of the cement composition.