Geochemical Characteristics and Implications of Shale Gas in Jiaoshiba, Eastern Sichuan, China
Lin Junfeng
Hu Haiyan
Li Qi
Abstract：The Wufeng-Longmaxi shales in Jiaoshiba is rich in natural gas.However, the research on the geochemical characteristic of the shale gas is weak, and its geological significance is still unclear.This article discusses the origin type and the "full reversal" carbon isotopic composition of shale gas from Wufeng Formation-Longmaxi Formation based on the analysis of the shale gas component and its isotope.The high hydrocarbon generation potential of Wufeng-Longmaxi shales, the positive correlation of the abundance of organic carbon and the content of gas, the similar carbon isotope distribution between methane and kerogen and the overpressure in Wufeng Formation-Longmaxi Formation suggest the shale gas should be generated from and preserved in the Wufeng Formation-Longmaxi Formation.The content of methane and its isotope indicate the stage of thermal maturity for shale gas has reached the overmature phase and the shale gas is mainly dry gas.The shale gas is mainly formed from the cracking of oil generated early based on the ratio of ln(C1/C2) and ln(C2/C3).The"full reversal" carbon isotope distribution of shale gas resulted from the oil cracking in a relatively closed system and it also reflects a favorable preservation and accumulation conditions for shale gas.
Keywords：carbon isotopeshale gasWufeng FormationLongmaxi FormationJiaoshibapetroleum geology
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 1124-1133 )