Characteristics of Oil and Gas Reservoir Systems in China's Main Marine Residual Basins
Zhou Liqing//Geological Department of Northwest University, Xi'an, Shanxi Prov. 710065, Yang Shengliang, Zhang Huai//East China Petroleum Bureau of Star Petroleum Company of Sinopec, Nanjing , Jiangsu Prov. 210000
This paper is focused on the characteristics of oil and gas reservoir systems in the marine residual basins, such as Ordos basin, Sichuan basin, Tarim basin, Bohai Bay basin the middle and lower reaches of Yangtze River and DianQian-Gui area. It is concluded that the main elements of the oil and gas reservoir systems in China's main marine residual basins are related to their geotectonic locations and structural evolution history. There are the following characteristics. The structural subsidence effect of original basins controlled the types and distribution of main hydrocarbon source rock. Three effective types of source-reservoir-caprock assemblage formed under the control of the original basin structural evolution cycle. The structural effect in the late stage controlled the hydrocarbon source center of the residual basins in the late stage. The successive large-scale palaeohighs formed in the Caledonian, Hercynian and Indosinian periods are the main areas for oil and gas migration. The peak time for hydrocarbon source in the Paleozoic source area must be matched with the trap formation period. In the late structural transformtion, there are some compressional uplifts, providing the necessary reservoir space, traps and migration dynamics for oil and gas abundance and accumulation while keeping the oil and gas reservoirs undamaged. After the late structural transformation, the late sourcing period and the late oil and gas migration in the basin are controlled by post-transformation structural configuration.