DIFFERENCES OF HYDROCARBON ACCUMULATIONS IN THE DONGYING AND THE ZHANHUA DEPRESSIONS OF THE BOHAIWAN BASIN AND THEIR CONTROL FACTORS

Closely neighbouring in the Bohaiwan Basin, the Dongying and the Zhanhua Depressions have distinct discrepancies in the composition of hydrocarbon source rocks and the distribution of oil and gas pools. The master source rocks of the Dongying Depression consist of the Upper Sha 4 and the Lower Sha 3 Members, and the oil and gas pools mainly distributed in the Eogene(accounting for 91%)are dominated by lithological, structural anticline and fault block ones. However, the wource rocks of the Zhanhua Depression consist of the Sha 3 and the Sha 1 Members, and the oil and gas pools mainly distributed in the Neogene(accounting for 90%)are dominated by buried hill draping structure ones. The analyses of subsi dence processes and fault depression extension features showed that the distribution of hydrocarbon was controlled by fault depression tectogenesis, depocenter wandering and effective source rocks.