Spatial differentiation of submarine fans and distribution patterns of high-quality reservoirs in Miocene Meishan Formation, block 13-2, Lingshui Sag, Qiongdongnan Basin

Since the discovery of high-yield gas flows from the Miocene Meishan Formation in well LS13-C of block 13-2 in the Lingshui Sag, Qiongdongnan Basin, subsequent exploration drilling has failed to achieve commercial breakthroughs. Previous exploration practices indicate that the distribution of favorable reservoir facies belts controlled by sedimentary systems is the key to successful exploration in this area. To address problems such as a weak understanding of spatial differentiation and unclear exploration directions in previous studies of submarine fans in the Meishan Formation of block 13-2, the study integrated drilling data and 3D seismic data, combined with sequence stratigraphic analysis, paleogeomorphology restoration, and sedimentary microfacies identification. The sedimentary spatial differentiation characteristics and reservoir development controlling factors of submarine fans in the low-stand systems tract (LST) of the second member of the Meishan Formation were systematically revealed. The results showed that the submarine fans in the Meishan Formation in this area primarily developed in the LST of the second member, and could be further divided into four types based on differences in sedimentary characteristics: eastern trench-confined type, central channelized type, western fault-controlled slope-break type, and lobate-shaped submarine fans. The development of submarine fan reservoirs was jointly controlled by sedimentary facies belts and dissolution modification. Among them, the western fault-controlled slope-break submarine fan developed in the downthrown block of the synsedimentary fault F2 exhibited favorable reservoir development conditions (thickness and physical properties) and natural gas accumulation conditions, and should be the next primary exploration target. The proposed multi-type submarine fan development model controlled by multi-stage slope-break zones provides a theoretical basis and exploration support for deep-water submarine fan exploration in the Qiongdongnan Basin.