Numerical Sedimentary Simulation Of Braided Delta Of Huagang Formation In Xihu Depression

Oligocene Huagang Formation of Xihu Depression in the East China Sea found to be a thick braided delta deposit and good gas reservoir,which can be divided into six members: H1,H2,H3,H4,H5,and H6.Due to this study area located in deep water,with few wells drilled and limited data extracted,the sediment source location and reservoir distribution remain unclear.For this reason,we conducted numerical sedimentary simulation in this area.With seismic data,well logging and core analysis etc.,we re-established the sedimentary processes in Xihu Depression during Oligocene and predicted total sediment,sand,silt and shale distribution and evolution and sedimentary facies distribution.In this study,we found that the main controllers of the braided delta deposit in Xihu Depression are its ancient landform before the sedimentary processes,sediment supply,source location,and sea level changes etc.With the help of the numerical sedimentary simulation platform Dionisos,this study shows good results.1.It affirmed three sediment source location: western Haijiao Uplift and Yushan Uplift,northern Hupijiao Uplift and eastern Diaoyu island folded-uplift Belt;2.This study reconstructed the distribution extent and evolution of total sediment,sand,silt and shale.The braided delta is mainly located on the west and east slopes,the sediment thickness decrease from north to south.In the early stage,with terrigenous clastic debris was transporting into the depression,the total sediment was prograding into the lake center.Sand and silt mainly formed the braided delta front.Silt can transport further than sand.In the middle stage,with abundant sediment,sand and silt formed thick continuous braided delta front,which could be treated as good reservoir.In the late stage,lake area was reducing,sand and silt formed braided delta plain.Shale is mainly distributed in the middle of the lake.3.Huagang Formation of Xihu Depression mainly has sedimentary subfacies like braided delta plain,braided delta front and deep lake.This is the first time to apply numerical sedimentary simulation into natural gas study of Xihu Depression.Applying numerical simulation reconstructed sedimentary processes and analyzed sedimentary evolution.The research provides an insight into future hydrocarbon exploration and development.