Distribution rule and main controlling factors of the marine facies hydrocarbon substances in the middle and upper parts of Yangtze region, China
Under the guidance of the tectonic-sequence stratigraphy, sedimentology and lithofacies palaeogeography and dynamic evolutionary view, the authors reappraise the distribution of the Sinian-Paleozoic hydrocarbon source rocks in the middle and upper parts of the Yangtze region. The vertical distribution of carbonate reservoirs is correlated well to the sequence stratigraphic framework, that is, to the transgressive system in the second order sea-level change cycle. The muddy source rocks are dominant in the main hydrocarbon source rocks and the carbonate, siliceous source rocks secondary. Their layers are good and a singl layer thickness is thinner. The hydrocarbon source rock types of parent materials and the organic evolution regularly change with the time. The Doushantuo Formation, Qiongzhusi Formation, Longmaxi Formation and the Upper Permian source rocks with better quality contribute a greater accumulation of oil and gas. The horizontal distribution and development of the favorable source rocks have differences in the sequence stratigraphic framework. The hydrocarbon source rocks are widely distributed over Sichuan Basin, only the lower-assemblage of source layers is residually preserved in Jianghan basin, however, the lower-assemblage of source layers has remained in the western border region of Xuefeng and all levels of source rocks have relatively developed in the Guizhou-Guangxi region. The distribution of the muddy source rocks are most wide with the most stable horizons, thickness and lithofacies and better organic geochemical indicators. Through the comprehensive analysis, the authors conclude that the gathering of hydrocarbon source rocks is controlled by the tectonic setting, the nature of the basin, paleoclimate, depositional environments and palaeogeography, and related to the rising of sea level with different causes. The hydrocarbon substances are always aggregated in the coastal coal-bearing system, stranded in shelves, restricted in bays, restricted in platforms, basins, continental slopes and deep-water basins.
国家科技期刊平台
NSTL
万方数据
维普
