Key Laboratory of Coalbed Methane Resources and Reservoir Formation on Process;
Ministry of Education;
China University of Mining and Technology;
Xuzhou 221008;
Jiangsu;
China;
School of Resources and Geosciences;
China University of Mining and Technology;
Xuzhou 221116;
Jiangsu;
China;
organic-rich shale; molecular structure; kerogen; HRTEM; Sichuan Basin;