Preliminary prediction and evaluation on source rock in low exploration basin—A case study from the northeast depression, South Yellow Sea basin, East China

Low exploration activity fields (e.g., deep formation, deep water, and new exploration areas) are of great importance for petroleum exploration. The prediction of source rocks is critical to the preliminary evaluation of low exploration activity fields, which will determine the early strategic electoral district and decision of exploration activity. The northeast depression is a new exploration area at the South Yellow Sea basin at present. Based on lots of seismic data in the study area and a few of well data in adjacent homologous depression, the early evaluation of source rock in the northeast depression was finished by comprehensively using the techniques of geological analogy, geophysical inversion and basin modeling, and an integrated methodology about preliminary evaluation of source rocks to low exploration activity fields is also presented. The methodology consists of three aspects: (1) prediction of the main formation of major source rocks, based on analogy analysis of seismic reflection characteristics and quality of source rocks in adjacent homologous depression; (2) method of seismic attribution to determine the thickness of source rocks; and (3) prediction of vitrinite reflectance, based on basin modeling technique to determine the maturation of source rocks. The results suggest that the source rock of the Taizhou (泰州) Formation is the most important interval for hydrocarbon generation in the northeast depression, which is characterized as high TOC, fine OM type, huge thickness, and high maturity. The western subdepression is the most important hydrocarbon kitchen in the northeast depression.