Seismic and sedimentary facies analysis and prediction of favorable Permian source rocks in the South Yellow Sea basin

The Permian source rock is one of the high-quality hydrocarbon source rocks in the South Yellow Sea basin. However, the seismic data available is so poor in quality that the distribution pattern of Permian source rocks is not clear. Based on the recently acquired and processed seismic data, integrated with old seismic data and well log datafrom the basin, by means of single well facies and seismic-sedimentary facies analysis, we discerned the distribution pattern of sedimentary facies and favorable source rocks of early and late Permian. It is revealed that duringthe period of early Permian, the western part ofLaoshan uplift and the western part of Qingdao depressionare both dominated byplatformfacies, while the eastern part of Laoshan uplift and the eastern part of Qingdao depression dominated by basin facies. During late Permian, however, the western part of Laoshan uplift and the northwestern part of Qingdao depression are covered by deltaic front facies, and the southern part of Qingdao depression by delta plain facies, whereas the northeastern part of Qingdao depression and the eastern part of Laoshan uplift are occupied by littoral-shallow facies. Combining the favorable sedimentary facies together with the residual stratigraphic thickness, we suggest thatthe middle part of the Laoshan uplift and the northeastern part of the Qingdao depression bethe favorable source rocks distribution area of lower Permian; the mid-eastern part of the Laoshan uplift and the northeastern part of the Qingdao depression be favorable source rocks distribution area of upper Permian.