Quantitative Characterization of Brittle Minerals in Shale Gas Reservoir, Jiaoshiba Area, China

Abstract

Jiashiba area is the first industrialized area of shale gas in China. The Wufeng formation and the lower of Longmaxi formation belonging to the Ordovician and the Silurian respectively are primary exploration interval. The methods and technology of exploration and development in Jiashiba area will be a good example for shale gas development in China. The prediction of the brittle minerals distribution in the shale based on the geological and geophysical data is a important technique in the shale gas development because the brittle minerals have important effect on fracture generation in the shale gas development. Laboratory test data of 421 were collected and analyzed. The results show that the minerals composition of the shale gas reservoir in the lower of Longmaxi formation is composed of quartz, feldspar, pyrite, clays and carbonate minerals, and that the brittle minerals and clays are about 45-55% and 40-50% respectively. The content of brittle minerals in the Jiaoshiba area is higher than that in the Barnett shale. Based on the laboratory test data and geophysical data, the statistics shows that Young's modulus and Poisson ratio in the interesting interval is negatively correlated with the content of quartz, so the high Young's modulus and low Poisson's ratio indicate the high brittle zone. The pre-stack inversion of 3D seismic data was carried out to calculate Young's modulus and Poisson ratio. The distribution maps of Young's modulus and Poisson ratio indicate a high brittle zone, which has a good agreement with the fact indicated by the drilling wells.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016