--> Abstract: Characterization and Quantitative Assessment of Petroleum Source Rocks for Fault-Fracture Mesh Petroleum Plays in the Zhanhua Depression, Bohai Bay Basin, by Yongshi Wang, Maowen Li, Xiongqi Pang, Dishi Shi, Shanwen Zhang, and Dongxia Chen; #90039 (2005)

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Characterization and Quantitative Assessment of Petroleum Source Rocks for Fault-Fracture Mesh Petroleum Plays in the Zhanhua Depression, Bohai Bay Basin

Yongshi Wang1, Maowen Li2, Xiongqi Pang3, Dishi Shi1, Shanwen Zhang1, and Dongxia Chen3
1 SINOPEC Shengli Oilfield Company, Dongying, China
2 Geological Survey of Canada, Calgary, AB
3 Petroleum University (Beijing), Beijing, China

In the prolific Zhanhua Depression of the Bohai Bay Basin, eastern China, over 76% of the proven petroleum reserves occur in the Neogene Guantao and Minhuazhen formations. Detailed geological and geochemical mapping of the Phanerozoic strata in this area reveals that oil shales and dark mudstones in the Es4, Es3 and Es1 members of the Eocene-Oligocene Shahejie Formation have excellent potential as petroleum source rocks. Regional distributions of total organic carbon content, kerogen type and thermal maturation indicate that abundant mature source rocks are present in several discrete sag areas bounded by extensive basement-related fault networks. In contrast, source rocks along the paleo-topographic highs are currently immature with respect to the generation of conventional oils. This study examined the key molecular characteristics in relation to source facies variations in lacustrine sediments. The hydrocarbon source potential and expulsion efficiency for each of the source rock units were evaluated, which integrated the source rock characteristics with regional thermal subsidence and sediment burial. An important observation made during this study is the striking contrast between the source potential and proven oil reserves within each stratigraphic section, illustrating how significant the migration of hydrocarbon fluids derived from deep mature source kitchens through over 2000 m of fine-grained formations must have been to form several giant oil accumulations in the shallow strata. These results support the concept of the “Neogene fault-fracture mesh petroleum plays” proposed by Zhang et al. (2004) and the vital role that the faults and fracture systems have in controlling hydrocarbon migration conduits and accumulation habitat in this rift basin.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005