Distribution characteristics, exploration and development, geological theories research progress and exploration directions of shale gas in China

The shale gas resources in China have great potential and the geological resources of shale gas is over 100 x10(12) m(3), which includes about 20x10(12) m(3) of recoverable resources. Organic-rich shales can be divided into three types according to their sedimentary environments, namely marine, marine-continental transitional, and continental shales, which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic. The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas, and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas, with a shale gas production of up to 20x10(9) m(3) in 2020. China has seen rapid shale gas exploration and development over the last five years, successively achieving breakthroughs and important findings in many areas and strata. The details are as follows. (1) Large-scale development of middle-shallow shale gas (burial depth: less than 3500 m) has been realized, with the productivity having rapidly increased; (2) breakthroughs have been constantly made in the development of deep shale gas (burial depth: 3500-4500 m), and the ultradeep shale gas (burial depth: greater than 4500 m) is under testing; (3) breakthroughs have been made in the development of normal-pressure shale gas, and the assessment of the shale gas in complex tectonic areas is being accelerated; (4) shale gas has been frequently discovered in new areas and new strata, exhibiting a great prospect. Based on the exploration and development practice, three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China. (1) in terms of deep-water fine-grained sediments, organic-rich shales are the base for the formation of shale gas; (2) in terms of high-quality reservoirs, the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation; (3) in terms of preservation conditions, weak structural transformation, a moderate degree of thermal evolution, and a high pressure coefficient are the key to shale gas enrichment. As a type of important low-carbon fossil energy, shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality. Based on the in-depth study of shale gas geological conditions and current exploration progress, three important directions for shale gas exploration in China in the next five years are put forward. (C) 2022 China Geology Editorial Office.