Hydrocarbon accumulation and key exploration & development technologies of Changning-Weiyuan marine shale gas field, southern Sichuan

Abstract

China is rich in shale gas resources and has broad prospects for development. However, the quality of shale gas resources in China is different from that in the United States, so independent unique technologies are urgently required in China. In this regard, PetroChina has carried out theoretical and technical researches systematically on shale gas in Longmaxi Formation in southern Sichuan according to its geology-engineering characteristics. Guided by the “three-control” theory for marine shale gas enrichment and high yield (i.e. sedimentary diagenesis controls reservoir, preservation conditions control accumulation, and continuous thickness of Type I reservoir controls production), six key exploration and development technologies in southern China have been innovatively developed for marine shale gas which experienced multi-stage tectonic evolution. The technologies include comprehensive geological evaluation technology, development optimization technology, optimal and fast drilling technology for horizontal well, volume fracturing technology for horizontal well, factory-like operation technology, and efficient clean production technology. These technologies have enabled the large-scale commercial recovery of shale gas. By the end of 2019, PetroChina had obtained proved geological reserves of 1.06 × 1012 m3, had built production capacity of 10 × 109 m3, and had cumulative gas production of 20 × 109 m3 in southern Sichuan. The remarkable results of application are of great significance for vigorously developing shale gas industry to reduce external dependence, ensure national energy security, and realize the strategy of “ecological priority and green development".