School of Geoscience;
China University of Petroleum;
Qingdao;
Shandong 266580;
China;
Strategic Research Center of Oil and Gas Resources;
Ministry of Natural Resources of the People’s Republic of China;
Beijing 100034;
China;
Department of Earth Sciences;
Durham University;
Durham DH13LE;
UK;
distribution characteristics of natural gas; accumulation model; coal-formed gas; Permo-Carboniferous coal measures; Bohai Bay Basin;