Analysis of gas migration patterns in fractured coal rocks under actual mining conditions

Thermal Science

卷:21

Ai Ting¹  Qiu Zhiqiang²  Zhang Zetian²  Xie Jing²  Gao Mingzhong² 

[1] Sichuan University, College of Architecture and Environment, Chengdu, China;

[2] Sichuan University, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu, China + Sichuan University, College of Water Resources and Hydropower, Chengdu, China;

关键词: gas-flow;    field test;    fracture network;    evolution characteristics;   

DOI  :  10.2298/TSCI17S1275G

来源: DOAJ

【 摘 要 】

Fracture fields in coal rocks are the main channels for gas seepage, migration, and extraction. The development, evolution, and spatial distribution of fractures in coal rocks directly affect the permeability of the coal rock as well as gas migration and flow. In this work, the Ji-15-14120 mining face at the No. 8 Coal Mine of Pingdingshan Tian’an Coal Mining Co. Ltd., Pingdingshan, China, was selected as the test site to develop a full-parameter fracture observation instrument and a dynamic fracture observation technique. The acquired video information of fractures in the walls of the boreholes was vectorized and converted to planarly expanded images on a computer-aided design platform. Based on the relative spatial distances between the openings of the boreholes, simultaneous planar images of isolated fractures in the walls of the boreholes along the mining direction were obtained from the boreholes located at various distances from the mining face. Using this information, a 3-D fracture network under mining conditions was established. The gas migration pattern was calculated using a COMSOL computation platform. The results showed that between 10 hours and 1 day the fracture network controlled the gas-flow, rather than the coal seam itself. After one day, the migration of gas was completely controlled by the fractures. The presence of fractures in the overlying rock enables the gas in coal seam to migrate more easily to the surrounding rocks or extraction tunnels situated relatively far away from the coal rock. These conclusions provide an important theoretical basis for gas extraction.

【 授权许可】

Unknown