CFD simulation on the generation of turbidites in deepwater areas: a case study of turbidity current processes in Qiongd
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CFD simulation on the generation of turbidites in deepwater areas: a case study of turbidity current processes in Qiongdongnan Basin, northern South China Sea JIANG Tao1,2*, ZHANG Yingzhao3, TANG Sulin1, ZHANG Daojun3, ZUO Qianmei3, LIN Weiren2,WANG Yahui3, SUN Hui1, WANG Bo1 1
Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China 2 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi 783-8502, Japan 3 Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China Received 20 June 2014; accepted 28 September 2014 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2014
Abstract Turbidity currents represent a major agent for sediment transport in lakes, seas and oceans. In particular, they formulate the most significant clastic accumulations in the deep sea, which become many of the world’s most important hydrocarbon reservoirs. Several boreholes in the Qiongdongnan Basin, the northwestern South China Sea, have recently revealed turbidity current deposits as significant hydrocarbon reservoirs. However, there are some arguments for the potential provenances. To solve this problem, it is essential to delineate their sedimentary processes as well as to evaluate their qualities as reservoir. Numerical simulations have been developed rapidly over the last several years, offering insights into turbidity current behaviors, as geologically significant turbidity currents are difficult to directly investigate due to their large scale and often destructive nature. Combined with the interpretation of the turbidity system based on highresolution 3D seismic data, the paleotophography is acquired via a back-stripping seismic profile integrated with a borehole, i.e., Well A, in the western Qiongdongnan Basin; then a numerical model is built on the basis of this back-stripped profile. After defining the various turbidity current initial boundary conditions, including grain size, velocity and sediment concentration, the structures and behaviors of turbidity currents are investigated via numerical simulation software ANSYS FLUENT. Finally, the simulated turbidity deposits are compared with the interpreted sedimentary bodies based on 3D seismic data and the potential provenances of the revealed turbidites by Well A are discussed in details. The simulation results indicate that a sedimentary body develops far away from its source with an average grain size of 0.1 mm, i.e., sand-size sediment. Taking into account the location and orientation of the simulated seismic line, the consistence between normal forward simulation results and the revealed cores in Well A indicates that the turbidites should have been transported from Vietnam instead of Hainan Island. This interpretation has also been verified by the planar maps of sedimentary systems based on integration of boreholes and seismic data. The identification of the turbidity provenance will benefit the
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