Oil and Gas Exploration Risk Evaluation and Screening of Favorable Areas for Future Exploration in Shenxian Sag, Bohai Bay Basin, China

摘要

Geological risk evaluation is essential for successfully improving exploration. A new method is proposed to evaluate geological risk objectively. Firstly, based on the study of petroleum system elements, the proposed method extracts major factors controlling petroleum accumulations and establishes a geological parameter set and corresponding values for each geological parameter. Secondly, with die calibration of exploration well outcome, it applied Mahalanobis distance and fuzzy logic approach to generate values of favorability for each exploration well and then established a template to convert the favorability to a probability of petroleum occurrence. At last, the model is applied to the study area, giving the exploration risk value. As an example, the proposed method is used in third member of the Oligocene Shahejie Formation (Es3) in Shenxian Sag, Bohai Bay basin. Data from exploration drilling, seismic interpretations and petroleum system models of previous studies are integrated to yield a probability map of petroleum occurrence that visualizes the geological risk. Several prospective areas, such as Sherman and Yuke, are highlighted in the probability map by low geological risk values, providing conceptional information for future exploration planning. The proposed method overcomes the subjectivity in conventional methods and provides a means for a consistent and reproducible estimation of geological risk in the whole play. The successful application indicates the significance and indispensability in reducing exploration risk of this proposed method.