Unconventional gas resources in China

Abstract

Coalbed methane, tight and shale gas are three important unconventional gas resources in China. ‘‘According to data from the Ministry of Land and Resources, at the end of 2013, China had 11, 12 and 25 trillion cubic meters, respectively of remaining technically recoverable resources of coalbed methane, tight gas and shale gas which are still in the early stage of development’’. (Source CNPC and ARA International Limited). China is developing its shale gas exploration and exploitation strategies for economic reasons and social aspects (so-called ‘‘shale gas revolution’’). Huge shale gas reserves provide a reliable source for sustaining China’s economic development and contributing to China’s ‘‘Energiewende’’. Zhao et al. (2015a) analyze the strategic measures and advantages for a safe and vigorous development of shale gas in China and review the developments of hydraulic fracturing technologies in China. Economic exploitation for shale gas is highly dependent on the complexity of the fracture network caused by hydraulic fracturing technology, so it is necessary to accurately assess the effect of the fracture network on gas flow behavior and productivity (Li et al. 2015c). This thematic issue is particularly dedicated to recent researches in unconventional gas resources in China related to the reservoirs indicated in Fig. 1 in order to substitute coal by ‘‘clean’’ gas energy resources as a transitional technology towards renewable energy resources. The thematic issue compiles theoretical, experimental as well as field studies in China. Different reservoir types are under investigation such as tight and shale gas reservoirs as well as coal mines with coalbed methane resources. Fundamental aspects on process understanding in unconventional gas reservoirs as well as the international context of research and technology deployment are discussed in this volume. Tight gas reservoirs have become an important resource for the world’s gas supply. Such reservoirs have very low permeability (usually below 0.1 mD) and show a strong stress sensitivity to fluid transport properties and a considerable productivity decline during the production process due to decreasing reservoir pressure as well as increasing effective stress. In an experimental study by Albrecht and Reitenbach (2015) several measurement series were performed on plugs from the North-German Rotliegend tight gas reservoirs to determine the effects of changing stress and pore pressure conditions on reservoir & Olaf Kolditz olaf.kolditz@ufz.de