Experimental Study on the Cement-Based Materials Used in Coal Mine Gas Extraction for Hole Sealing

Abstract

Gas drainage is an important method to prevent and control gas disasters. Sealing materials have an important impact on the gas drainage effect. To improve the extraction rate, the configuration and related characteristics of sealing materials were studied in this study. It was found that the fluidity increased gradually with the increase of the dosage of the suspension concentrate (SC). The water−cement ratio was directly proportional to the setting time of the slurry. Also, the mixing amount of the special cement was inversely proportional to the setting time of the slurry. The influence of the amount of foaming agent, special cement, and suspending agent on the expansion rate of the slurry was positive, and the influence gradually weakened. When the water−cement ratio of cement-based materials was 0.6, the special cement content percentage was 6, the suspension agent content percentage was 3, the plasticizer content percentage was 0.7, the early strength agent content percentage was 1.2, and the foaming agent content percentage was 0.2, the sealing effect was the best. The research results suggest that the porosity and pore length of the cement-based material are smaller than those of polyurethane, and its sealing property was better. This could further increase the sealing effect of the gas borehole, thereby facilitating gas extraction.

Air Leakage Characteristics of Gas Boreholes in Deep Coal Seams and Application of Short-Hole Grouting and Plugging

“…16 Meanwhile, cementitious materials are widely used owing to their good fluidity and supportive nature. 17,18 To achieve efficient gas drainage from boreholes, Hu et al proposed a particular bag-type borehole sealing device. 19 Fu et al developed a material with dual expansion sources to seal boreholes via bag grouting sealing, which improved gas drainage efficiency in boreholes.…”

“…Although convenient, polyurethane is not effective in sealing drill holes due to its irritating odor and the fact that it can only fill large fissures near the well wall . Meanwhile, cementitious materials are widely used owing to their good fluidity and supportive nature. , …”

“… 16 Meanwhile, cementitious materials are widely used owing to their good fluidity and supportive nature. 17 , 18 …”

The Hole Sealing Technology of Solid–Liquid Materials with Three Pluggings and Two Injections for Gas Extraction Hole in the Coal Mine

“…After years of continuous optimization, it efficiently solves water segregation and consolidation fissuration problems. Therefore, it has become the most widely used sealing material . Barkman and Abrams proposed the famous one-third rule: the particles with sizes equal to or larger than 1/3 of the mean pore size can virtually plug cracks, namely the “3D principle” .…”

“…Therefore, it has become the most widely used sealing material. 25 Barkman and Abrams proposed the famous one-third rule: the particles with sizes equal to or larger than 1/3 of the mean pore size can virtually plug cracks, namely the “3D principle”. 26 Due to the large particle size of the existing CB material, it is difficult to plug the fine cracks of coal strata.…”