Thermal History and Hydrocarbon Kitchen Evolution in the Jianghan Basin
Li, Zongxing; Zhao, Yue; Liu, Chenglin; Zhao, Ping
Pre-Cenozoic marine residual basin is the second main direction of oil and gas exploration in China. Thermal history and hydrocarbon maturation evolution have a close relationship with hydrocarbon generation, migration, accumulation, and dynamics process; the study of thermal regime and hydrocarbon kitchen evolution may offer valuable informationfor further exploration.
The present geothermal gradient and terrestrial heat flow was calculated of 18 wells in the Jianghan Basin. We report nine measured terrestrial heat flow values based on the data of detailed thermal conductivity and systematical steady-state temperature. Thermal history analyses based on vitrinite reflectanceand apatite fission track data indicate that: Before the Indosinian event, the heat flow of the Jianghan Basin was low. After 240Ma, the heat flow started to increase. The basin's heat flow was up to maximum of~68mW/m2 in 157Ma, and then it started to fall, the descending rate increased since 43Ma. Furthermore, tectonic subsidence analysis reveals that the tectonic subsidence of the Jianghan Basin in the Cretaceous to early Miocene was characterized by synrift initial subsidence followed by the subsequent thermal subsidence. The thermal history and tectonic subsidence history of Jianghan Basin are of great significance to petroleum exploration and hydrocarbon source assessment, because they bear directly on issues of petroleum source rock maturation.The maturation and the hydrocarbon generation intensity evolution history of the P2d source rocks are modeled.The results show that the P2d source rocks are in a higher degree of maturation at present, and the Yuan'an and Herong Sags are the two most important kitchens in the Late Jurassic, Xiaoban Sag is another most important kitchen during the Late Cretaceous to late Paleogene, and the Zhijiang and Mianyang Sags are other two important hydrocarbon kitchens in the Late Cretaceous. The Mianyang Sag and Yichang Ramp are the favorable exploration targets in the future. This study may provide new insight for the understanding of the oil and gas exploration potential for the Jianghan Basin.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013