煤中可溶有机质对瓦斯赋存及煤与瓦斯突出特性的影响

Soluble organic matter is an important part of the coal and large amounts of methane dissolved in it. This is an important morphological of gas occurrenceone. Soluble organic matter has some impact on coal gas occurrence, migration and emission of gas, and even coal and gas outburst. The project is based on geochemistry, surface and interface physics chemistry, fluid mechanics, gas dynamics etc. With the combination of several methods such as theoretical analysis, experimental simulation and experimental test, differences between the physical parameters mechanics parameters and gas adsorption-desorption characteristics of the raw coal and the extraction residue coal were researched，components of soluble organic matter within coal were examined. By gas dissolution experiments on the extraction of soluble organic matter and experimental analysis of assembling form of methane molecules and soluble organic matter in solution， to obtain influence of soluble organic matter within coal on coal seam gas reservoir and migration，and reveal coal skeleton structure-soluble organic matter-gas system interaction mechanism.The effect of soluble organic matter within coal on gas seepage under different ground stress and gas pressure was studied, and the coupling relationship between diversified gas outburst parameters and soluble organic matter within coal was analyzed, to reveal the effect of soluble organic matter on coal and gas outburst characteristics.

可溶有机质是煤的重要组成部分，可溶解大量甲烷，是煤中瓦斯赋存的重要形态之一，对煤的瓦斯赋存、瓦斯运移和放散、乃至煤与瓦斯突出均有一定影响。本项目基于地球化学、表面及界面物理化学、流体力学、瓦斯动力学等多学科交叉理论，采用理论分析、实验模拟和实验测试相结合的方法，分析原煤和抽提残煤的物性参数、力学参数及瓦斯吸附-解吸特性的差异，化验煤中可溶有机质成分，对抽提的可溶有机质进行瓦斯溶解实验，观测溶液中甲烷分子与可溶有机质的聚集形态，从而获得煤中可溶有机质对煤层瓦斯储集和运移的影响规律，揭示煤骨架结构-可溶有机质-瓦斯体系的相互作用机理。研究不同地应力、瓦斯压力条件下，煤中可溶有机质对煤体瓦斯渗流的影响，实验分析多元瓦斯突出参数与煤中可溶有机质的耦合关系，最终可以揭示可溶有机质对煤与瓦斯突出特性的影响。

煤是一种复杂的有机岩石，除含大分子固体骨架外，还含大量可溶于有机溶剂的小分子有机物，它们存在于煤基质的孔隙甚至大分子网络结构中，必然会对煤层瓦斯储运及突出危险产生一定影响，但其影响规律及机理还缺乏深入研究。本项目立足于煤体结构及其物质组成，采用理论分析、实验模拟和实验测试相结合的方法，在分析原煤和抽提残煤的孔隙结构、吸附、扩散及渗流特性差异的基础上，深入分析了可溶有机质对煤孔隙作用机理，进而探讨其对煤吸附特性以及扩散与渗流特性的影响机理。测试研究了可溶有机质对突出参数的影响，进而揭示了其对煤与瓦斯突出危险的作用机制。通过3年的研究，获得以下研究成果：.1）分别采用扫描电镜、压汞法及气体吸附法系统地观察和测试了原煤与残煤孔隙表面特征及其孔隙结构参数，对比分析了原煤与残煤孔隙特征及结构参数的变化规律；并应用分形理论定量化分析了它们的变化规律。抽提后，简化了煤孔隙结构，降低了煤中微小孔比例。.2）开展了原煤、残煤及含油煤甲烷等温吸附实验，分析了原煤和残煤吸附甲烷特征参数的变化规律；选择合适的可溶有机质模型化合物进行了甲烷溶解实验，发现可溶有机质可溶解定量甲烷；最终揭示可溶有机质可提高煤吸附瓦斯能力。.3）开展了原煤和残煤瓦斯放散实验和径向渗透率测试实验。深入分析了原煤和残煤的瓦斯放散量、放散速度、放散系数和渗透率变化规律。表明可溶有机质被溶出后，简化了煤的孔隙结构，减少扩散阻力，增扩煤的渗流通道，减少渗流阻力，有利于瓦斯在煤层中运移出来。.4）测试了原煤和残煤的多种突出参数，可溶有机质被抽提后，煤体蠕变能力减弱、结构单一化，抗压及抗拉强度增大；同时K1值及△h2等突出参数降低，瓦斯放散初速度减小，结合瓦斯含量变化趋势，认为煤中可溶有机质的存在对煤与瓦斯突出有一定的促进作用。项目研究成果对矿井瓦斯抽采及突出预测提供了新的拓展手段。