| Among many coal mine accidents,gas accident is the main threat to coal mine safety in China.In order to deal with the occurrence of gas accident,gas drainage is usually carried out in coal seam of gas mine to solve the high concentration of gas in the roadway of gas mine.However,the sealing quality of gas drainage borehole directly affects the drainage effect.In China,the research on plugging materials started relatively late,and the study learned from many foreign experiences.The traditional plugging materials have certain limitations,and the chemical gelling plugging technology,as an international frontier plugging technology,has been paid attention to.Therefore,in this paper,polyvinyl alcohol,diethanolamine(triethanolamine)titanate isopropyl ester,carboxymethyl cellulose three components through chemical cross-linking reaction to prepare a new polyvinyl alcohol gel as mining drilling plugging material,and study the gel performance,laboratory simulation drilling plugging to evaluate its plugging effect.First,polyvinyl alcohol,isopropyl titanate(triethanolamine)and carboxymethyl cellulose using chemical crosslinking reaction preparation of PVA gel,gel strength and gel time of polymer,cross-linking agent in the gel and the type of retarder concentration screening,to determine the best proportion of gel component that polyvinyl alcohol solution concentration was 7%,crosslinking agent 2 isopropyl titanate(triethanolamine)concentration was 2.2%,the retarder CMC concentration was 1.2%.The effects of temperature,p H,polyvinyl alcohol cross ratio and moisture on the properties of polyvinyl alcohol gel.The gel properties were more stable when the temperature range was 15? to 30?.The polyvinyl alcohol gels are sensitive to p H,and the polyvinyl alcohol gels have a cross ratio of 2 to 5.At the same time,tap water was selected as the solvent to increase the performance of polyvinyl alcohol gel.The physical and chemical properties and mechanical properties of the polyvinyl alcohol gel plugging material show that the water content of the gel is up to 81%,and the swelling rate of the gel is 21.5% after 200 min and remains stable.After the polyvinyl alcohol gel was placed at 5?-35? for 24 h,the water retention rate of the gel decreased from 99.47% to 94.22%,and the water loss rate was also lower at higher temperature,and no serious dehydration occurred.At the same time,the polyvinyl alcohol gel has the properties of wettability,adhesion and flame retardancy.Under the action of grouting pressure, the polyvinyl alcohol solution can penetrate into the coal-rock cracks and effectively seal the filling coal-rock cracks.TG and DSC analysis of the polyvinyl alcohol gel showed that the weight loss process of the polyvinyl alcohol gel was a heat absorption process,and the heat came from the evaporation of water in the early stage and the gasification of the polymer in the late stage.SEM analysis showed that there was no crack on the surface of the polyvinyl alcohol gel and it had a good sealing effect.Finally,polyvinyl alcohol gel was used to simulate gas drilling plugging experiment.The gel plugging process was mainly divided into two parts: glue injection and plugging.The glue injection was mainly used in double-liquid grouting method,and the plugging process used glue injection while plugging.The plugging experiment results show that the gel is stable when the negative pressure is 0.052 MPa.Meanwhile,the water retention rate of the gel is higher than 90% 50 days after the plugging and glue injection,and the plugging effect is excellent,which meets the requirements of coal rock fissure plugging materials.In this paper,there are 50 figures,14 tables and 89 references. |
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