**Preface to "Advances in Methane Production from Coal, Shale and Other Tight Rocks"**

Unconventional natural gas, including shale gas, tight gas, and coalbed methane, looks set to have an important role in the present and future clean energy structure. Technological advancements in horizontal drilling and hydraulic fracturing have spurred a rapid increase in unconventional energy production over the past decade. The application of new technologies has enabled natural gas and shale oil to be economically produced from shale and other unconventional formations. Further, various methods have been adopted to improve gas recovery, including but not limited to high-precision characterization of coal and shale reservoirs at multiscales, fast drilling and completion of wells with long laterals as well as large-scale volume fracturing. Numerous new techniques have emerged, such as multiple well-type development, fluid injection, nano-flooding, and enhancing biogenic methane generation methods.

This collection reports on the state of the art in fundamental discipline application of these techniques to methane production and associated challenges in geoengineering activities. Zheng et al. (2022) report on an NMR-based method for multiphase methane characterization in coals, which is helpful for understanding methane occurrence within deep coals. Wang et al. (2022) studied the genesis of bedding fractures in Ordovician to Silurian marine shale in the Sichuan basin, China, which is significant for shale gas production. Kang et al. (2022) proposed research focusing on the differentiation and prediction of shale gas production from horizontal wells, which can be applied in the Weiyuan Shale Gas Field, Sichuan Basin, China. Liang et al. (2022) studied the pore structure of marine shale from the terms of molecular interaction via the adsorption method. Zhang et al (2022) focus on the coal measures sandstone reservoir in Xishanyao Formation, at the Southern Margin of the Junggar Basin, and its sandstone diagenetic characteristics are fully revealed. As with the exploration on marine areas, Yao et al. (2022) report on the source-to-sink system in the Ledong submarine channel and the Dongfang submarine fan in the Yinggehai Basin, South China Sea.

There are 4 papers focusing on the technologies associated with hydrocarbon production from the tight rocks. Wang et al. (2022) report the analysis of pre-stack inversion in carbonate karst reservoir, which shows good application potential. Chen et al. (2022) conducted an inversion study on parameters of cascade coexisting gas-bearing reservoirs in coal measures in Huainan, south China, which is useful in the coal measure gas accumulation prediction and production. To ensure the safety of carbon capture and storage (CCS), Zhang et al (2022) report their analysis of available conditions for InSAR surface deformation monitoring in CCS projects. Additionally, to ensure the safety of coal mine production, Zhang et al. (2022) report the properties and applications of gel materials for coal gangue control.

All 10 papers featured focus on successful unconventional hydrocarbon production. We hope that the collection can be beneficial for readers in the field of unconventional oil and gas geology, and also to energy-related scholars.

**Acknowledgments:** We thank the representative colleges of the China University of Mining and Technology (Beijing) for supporting the compilation of this Special Issue. Editor Qisheng Su helped to coordinate this Special Issue.

> **Yong Li, Fan Cui, and Chao Xu** *Editors*
