Characteristics of Petroleum Systems and Plays in the Dongying Depression, Shandong, China

Youlu Jiang¹, Hua Liu¹, Le Zhang¹, Shanwen Zhang², and Ning Wang^2
1 China Petroleum University, Dongying, Shandong, China
² Shengli Petroleum Bureau, SinoPec, Dongying, Shandong, China

The Dongying depression, a typical petroliferous lacustrine basin in the Bohai Bay, China, is now in a high exploration maturity stage. However, understanding of its petroleum systems remains very important for future exploration. Two petroleum systems exist in the depression corresponding to two effective source rock units deposited in the Eocene sedimentary section. However, the source rocks occur across four different intra-basinal sags, with each of them exhibits distinct generation and expulsion history, making the overall petroleum system picture more complex. The two petroleum systems share the same geological elements for petroleum accumulations, although petroleum generation, migration and accumulation processes are independent from one another.

Within the two petroleum systems, eight petroleum plays can be identified based reservoir distribution, structural/stratigraphic configuration, and their relationship to petroleum source rocks. Within each play, hydrocarbon accumulation is closely related to hydrocarbon migration pathways from source rock sags. Although vertical hydrocarbon migration predominates, and was very active in areas where intensive faulting occurs, short-distance lateral migration is also demonstrated by existing hydrocarbon accumulations. Petroleum accumulations occur in areas direct adjacent to or within individual petroleum-generative sags.

The petroleum system and play analysis provides insights into future exploration directions within the maturely explored basin, and the results could be used in exploration of similar basins around the world.