Petro China Huabei Oilfield Company Jiangsu Provincial Key Lab of Coal-Based CO2 Capturing and Geological Storage, Research Institute Low Carbon Energy, China University of Mining and Technology Key Laboratory of Coalbed Methane Resources & Reservoir Formation Process, Ministry of Education, School of Mineral Resource and Geosciences, China University of Mining and Technology Institute of Petroleum Engineering, Heriot-Watt University Research Institute of Oceanographic Instrumentation, Shandong Academy of Sciences(SDIOl)

为准确测试煤岩甲烷扩散系数,通过采用片状煤基质作为检测样品,测试并分析了不同气体压力、煤阶与水分对甲烷扩散系数的影响。结果表明:片状样品保持了煤基质特有的空间结构,煤基质甲烷扩散系数(数量级10-1110-9m2/s)更符合实际;当温度一定时,无论是干燥样品、饱和水样品,还是低、中、高煤阶样品,煤基质甲烷扩散系数均随气体压力的增加而增大;而不同变质程度煤的吸附能力不同,随着煤的变质程度增加,煤岩吸附能力增强,但是煤基质的扩散系数随着变质程度增加呈现先降低后增加的趋势;水分的增加降低了基质对甲烷的吸附能力,难以形成较大浓度梯度,导致饱和水样品煤岩基质甲烷扩散系数比干燥样品低,干燥样品扩散速率快。

In order to discuss the pore interconnection features of the high rank coal, based on No.3 anthracite seam at the south part of Qinshui Basin as a study o bject, the 3D digitalized modeling method of the coal reservoir structure was applied to establish the multi grade pore crack network structure model of the seam and topick up the key parameters. In combination with the observation of the scanning electron microscope, the pore crack interconnection relationship and the contribution of the different origin type pore crack to the coal reservoir interconnection were further confirmed. The results showed that the pore throat of the high rank coal was fine a nd small and the high rank coal was mainly with the medium pores with a pore diameter less than 50 nm. the tortuosity of the crack was low, the section was mainly withthe square and regular triangle and the capillary resistance was low. The interconnection of the crack was poor and the medium pore with the pore diameter less than 50 nm would play the main function to the interconnection. The differential shrinking pores were the main nano interconnected pores. The pore development could formt he seepage network structure with a certain network topological property. The pore crack network structure could characterize the pore crack distribution features and t opological relationship and could release the digitalized and visualized characteristics of the coal and rock internal space.

国家科技重大专项资助项目(2016ZX05042-002)；国家自然科学基金资助项目(41530314,41272175)；