Structural controls on joint development in the so

Authors: Linlin Wang Bo Jiang Jilin Wang Zhenghui Qu Run Chen

Publish Date: 2016/04/22

Volume: 9, Issue: 5, Pages: 352-

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Abstract

The permeability of a coal reservoir fundamentally depends on joint development which is primarily structurallycontrolled However it is difficult to obtain joint data of underground coal seams Therefore in order to provide a theoretical basis for predictions of joint development and the location of highpermeability zones of underground coal seam joint orientation and intensity in beds outcropping above the coal seams were measured The study area is located on the southeastern margin of the Ordos basin of central China Field work shows that five subvertical joint sets are developed in the study area Sets III striking 145° and V striking 45° are the most dominant It is found that joint characteristics ie orientation and intensity are controlled by the structure For any particular lithology joint intensity not only shows a negative power function relationship with bed thickness but also is largely affected by structure and varies from high–low–high–low when traced from east to west across the area reflecting the location of the deformation belts ie fold and fault belts The Yanshan and Himalayan tectonic events which occurred after the Middle Jurassic are critical periods for joint formation Sets I and II are induced by an early EW oriented Yanshan compression Sets III and IV are the outcome of a later NWoriented Yanshan compression set V the result of a NEoriented compression linked to the Himalayan event The permeability of the No 5 coal seam of the Shanxi Formation is found to increase with increasing joint intensity in the overlying sandstone bedsThe research reported here was supported by Natural Science Foundation of Jiangsu Province No BK20150177 National Natural Science Foundation of China Nos 41430317 41572138 Scientific Research Foundation of Key Laboratory of Coalbased CO2 Capture and Geological Storage Jiangsu Province China University of Mining and Technology No 2015B04 and China International Science and Technology Cooperation Project No 2013DFB6014008

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