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Reservoir Prediction in Deep Lacustrine Turbidites, Liaozhong Depression, Liaodong Bay Basin, China

Jiang, Shu 1; Weimer, Paul 1; Cai, Dongsheng 2; Zhu, Guanghui 3; Zhu, Xiaomin 4; Hu, Xiaolin 3
1 Department of Geological Sciences, University of Colorado, Boulder, CO.
2 CNOOC China Ltd, Zhanjiang, China.
3 CNOOC Research Center, Beijing, China.
4 School of Geo-resources and Information, China University of Petroleum, Beijing, China.

Liaozhong Depression, located in the central Liaodong Bay basin of China, is a Tertiary rifted lacustrine basin with later superimposed strike-slip deformation. Cenozoic strata are 6-7 km thick consisting of fluvial-deltaic-fan deltaic and shallow to deep lacustine deposits. Most production in the past is from structural traps. The main exploration play currently is stratigraphic traps in the lacustrine turbidite sandbodies of the Oligocene Dongying Formation. The regional sequence stratigraphic framework was established in different parts of the basin by using 2D and 3D seismic data, well logs, paleontologic and geochemical data to identify prospective areas. The strata then were scanned to identify prospective turbidites with specific reflection patterns within the sequence stratigraphic framework. Some of the turbidite reservoirs have been drilled, so a good well-to-seismic tie is possible. RMS attribute analysis, 3D visualization, AVO, Poisson ratio and seismic inversion were then used to characterize the stratigraphic aspects of these turbidites in undrilled areas. Most of the turbidites developed associated with different order sequence boundaries and were controlled by location of sediment input, configuration of the faults (synsedimentary faults, and later strike-slip fault) and resulting topography, and abrupt gradient changes in the lakes. These turbidite traps are nearby to lacustrine source rocks. In addition, long-lived strike-slip faulting has acted as migration pathways for the generated oil and gas. Petroleum system modeling of the basin indicates that these turbidite traps have good potential. A recent discovery of one turbidite gas field confirms these predictions.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009