Source–reservoir relationships and hydrocarbon charging history in the central uplift of the south Yellow Sea basin (East Asia): Constrained by machine learning procedure and basin modeling

Abstract

The South Yellow Sea Basin (SYSB) is an area for oil and gas exploration in eastern China. The previous geological studies were mainly about the Mesozoic–Cenozoic strata, but no commercial hydrocarbon resource has been discovered up to now. This study focuses on the Silurian–Lower Triassic source-reservoir relationships and hydrocarbon charging history in the Central Uplift of the SYSB using the first scientific drilling well (CSDP-2). The well is drilled through the Paleozoic–Mesozoic deposits and yielded approximately 2736 m of cores. Multiple sets of effective source rocks and reservoirs with good source–reservoir relationships are identified and classified by means of support vector machines. The reservoir rocks are dominated by tight sandstone and dolomite with ultralow porosity and permeability. Hierarchical cluster analysis shows that the oil sources of the multiple reservoirs are mixed. Results of basin modeling and fluid inclusion analysis show that the hydrocarbon charging generally occurred during the Triassic to Late Jurassic, which is almost simultaneous with the densification of the Late Paleozoic reservoir rocks. This study indicates immense oil and gas resource potential of the study area. The Mesozoic tectonic thrust, uplift, and long-term denudation occurred in the East Asian continental margin, which are related to the Sulu collisional orogen and the Paleo-Pacific subduction, may have had significant impact on the hydrocarbon preservation and accumulation in the Central Uplift of the SYSB.