Gas charging history of the Yingcheng Formation igneous reservoir in the Xujiaweizi Rift, Songliao Basin, China

Systematic analysis of fluid inclusions was carried out on 34 samples from the Yingcheng Formation igneous reservoir of the Xujiaweizi rift, Songliao Basin, China. On the basis of petrographic characterization, the results of the microthermometric analyses indicated that the Yingcheng Formation igneous reservoir trapped six clusters of pure aqueous inclusions, and only four of them have the coeval gas-bearing aqueous inclusions been detected in the analyses. So the Yingcheng Formation igneous reservoir experienced four gas charging events during its evolutionary history. Combined with the research results of burial history and cap rocks, the four gas charging events happened during the time interval from 120 to 85 Ma, and every charging time is no more than 10 Ma. The main gas charging is the third, which happened during the time interval from 105 to 95 Ma.