Shorten the Learning Curve Through Technological Innovation: A Case Study of the Fuling Shale Gas Discovery in Sichuan Basin, SW China

Abstract

Based on a comparison of geological conditions for shale gas in China and those in America, combined with geological properties and surface conditions, we conclude that marine strata in south China having similar properties to those of America are targets for shale gas exploration, and the Sichuan Basin and its surrounding area is a favorable exploration area. Improved geological understanding and technological innovation are among the key factors that have helped Sinopec to shorten the learning curve in shale gas resource exploration and exploitation. After six years of research and exploration, the Fuling Shale Gasfield, which is the first major commercial shale gas play in China, was finally found in the Sichuan Basin in 2012 and successfully developed. Fuling Shale Gasfield is located in the Jiaoshiba structure, a broad box-shaped, faulted anticline. The shale gas producing layers are the Upper Ordovician Wufeng Fm. and Lower Silurian Longmaxi Fm. Comprehensive analysis of the shale gas reservoir indicates that organic matter content is the principal control on shale gas enrichment, the organic micropores are the main reservoir space, horizontal bedding fractures ensure horizontal seepage, and the high siliceous mineral content ensures good fracturing ability. Integration of those four properties in the Wufeng-Longmaxi shales is conducive to enrichment and exploitation of shale gas. The shale gas potential of the Wufeng-Longmaxi formations is mainly controlled by the original depositional environment which determines organic matter content and postdepositional conditions that promote shale preservation and gas retention within the shale after thermal maturation. Deposition and distribution of the shales are controlled by the platform depression environment, while thickness and high TOC content are the primary indicators for play evaluation. The late preservation conditions control the enrichment of shale gas, and the high pressure coefficient in the Sichuan Basin is the basis for evaluation of preservation conditions.