甲烷吸附前后高煤级煤孔隙结构粒径效应  

The grain size effect on pore structure characteristics of high-rank coal before and after the methane adsorption

作　　者：李腾 吴财芳[3,4] LI Teng;WU Cai-fang(College of Petroleum Engineering,Xi’an Shiyou University,Xi’an 710065,China;Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil&Gas Reservoirs,Xi’an Shiyou University,Xi’an 710065,China;School of Mineral Resources and Geosciences,China University of Mining&Technology,Xuzhou 221116,China;Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,Xuzhou 221116,China)

机构地区：[1]西安石油大学石油工程学院,陕西西安710065 [2]西安石油大学陕西省油气田特种增产技术重点实验室,陕西西安710065 [3]中国矿业大学资源与地球科学学院,江苏徐州221116 [4]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221116

出　　处：《天然气地球科学》2021年第1期125-135,共11页Natural Gas Geoscience

基　　金：国家科技重大专项“多煤层煤层气甜点选区选段技术”(编号:2016ZX05044-001);陕西省自然科学基础研究计划(编号:2019JQ-527);陕西省教育厅科研计划项目(编号:20JS116)联合资助。

摘　　要：针对3种不同粒径的高煤级煤开展了甲烷高压等温吸附测试,并对不同粒径煤样甲烷吸附前后的孔隙结构特征进行了对比研究。结果表明,不同粒径煤样的等温吸附曲线没有显著的差异,随着煤岩粒径的减小,煤岩的吸附速率和最大过剩吸附量呈逐渐增加的趋势。甲烷吸附前后,不同粒径煤样的孔隙结构发生了不同的变化。甲烷等温吸附前,随着煤岩粒径的减小,低温液氮吸附滞后环开度呈逐渐减小的趋势,等效吸附率曲率则先减小后增大;甲烷吸附后,DY-5煤样的低温液氮吸附滞后环开度减小,而DY-6煤样和DY-7煤样的低温液氮吸附滞后环开度有所增加,说明甲烷吸附对小粒径煤样中孔和大孔的影响较为显著。甲烷的吸附作用对各阶段孔隙均有影响。大粒径煤样在甲烷吸附作用影响下,孔隙连通性得以改善,而小粒径煤样在甲烷吸附作用后孔隙分布更加的集中。Methane isothermal adsorption experiments were carried out on the high rank coal samples with three different particle sizes,and dynamic change of the pore structure was measured with the low temperature N2 adsorption and the low temperature CO2 adsorption before and after the methane adsorption. The results show that the adsorption isothermal curves of the various grain sizes coal samples present no significant differences,the adsorption rate and maximum excess adsorption capacity increase with the decreasing particle sizes. Before the methane isothermal adsorption,the d( ’qde-qad)decreases with the decreasing grain sizes,while that for the equivalent desorption rate curvatures decrease first and then increase. After the methane adsorption,the d( ’qde-qad)for DY-5 coal sample decreases,while that for the DY-6 and DY-7 coal samples feature the contrary characteristics,indicating that the methane adsorption has a significant influence on the meso-and macropore structure for the small grain size coal samples. In fact,the methane adsorption could change the pore structures in the coal at all stages. For the coal samples with larger grain size,the pore connectivity is enhanced,while that for the coal samples with smaller grain sizes,the distribution of the pores would be more concentrate after the methane adsorption.

关 键 词：高煤级煤 甲烷吸附 粒径效应 孔隙结构 

分 类 号：TE122[石油与天然气工程—油气勘探]