Oil-Gas Inclusions and Reservoir Formation in Bozhong Depression of the Bohaiwan Basin
LI Rong xi 1,2 JIN Ku li 2 ZHONG Wen wen 3 1 (Open Lab of Ore Deposits Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002) 2 (China University of Mining and Technology, Beijing 100083) 3 (China Offshor
Two types of oil gas inclusions, the primary and the secondary, were recognized in the Tertiary clastic rocks in Bozhong Depression of the Bohaiwan Basin in Northeastern coastal area of China. These two types of oil gas inclusions recorded two stages of oil migration and accumulation in the region. The secondary porosity and fractures, filled with abundant secondary oil gas inclusions, are the kind of dissolution pore formed by the eluviation due to the uplift of the region at the end of the early Tertiary. Data from temperature measurements and analysis to compositions together with biomarkers of the oil gas inclusions indicate that the oil trapped in secondary porosity and fractures originated from the lower Tertiary lacustrine source rocks and the oil accumulations were controlled by the Tertiary tectonics and diagenesis. It is proposed that targets for oil exploration in the region should focus on the Tertiary sediments rather than the Pre Teriary depositions. Tectonics, sedimentary discontinuity between lower and upper Tertiary and reservoir prediction are the key subjects for oil prospecting in the region.