FAVORABLE LITHOFACIES AND SWEET SPOT OPTIMIZATION OF THE Ek21 SHALE OIL IN CANGDONG SAG, BOHAI BAY BASIN

To optimize the favorable lithofacies of shale and predict the sweet spots of shale oil distribution in the first sub-member of the second member of Kongdian Formation (Ek₂¹), the principal component analysis (PCA) is used to analyze three main geological components of shale oil, including resources (retained hydrocarbon), physical properties (porosity and permeability) and engineering properties (brittleness index and rock mechanics parameter). The results show that the lamellar felsic shale facies and lamellar mixed shale facies have high retained hydrocarbon content, with good porosity and permeability, and high brittleness index. Areas such as Wangguantun, south of Qilidian and southeast of Shenjiapu are all sweet spots of shale oil distribution with good oil-gas show.