1. School of Geoscience and Technology, Southwest Petroleum Univ., Chengdu, Sichuan 610500, China.
2. School of Geoscience and Technology, Southwest Petroleum Univ., Chengdu, Sichuan 610500, China; Natural Gas Geology Key Laboratory of Sichuan Province, Sothwest Petroleum Univ., Chengdu, Sichuan 610500, China (corresponding author).
3. PetroChina Coalbed Methane Co., Ltd., 9 Chaoqian Rd., Science Park, Changping District, Beijing 100020, China.
4. Exploration, Development and Construction Branch, PetroChina Coalbed Methane Co., Ltd., No. 115 Laodong Rd., Lianhu District, Xi’an, Shaanxi 710000, China.