Criteria of Geologic Risk Evaluation for Traps in Jiyang Depression

Differences exist in petroleum geologic conditions a-mong the three oil - bearing sequences of pre - Teriary, Paleogene and Neogene in Jiyang depression. Criteria of trap geologic risk evaluation are established based on study of the recent drilled traps. The newly established criteria can completely reflect current features of exploration and improve the accuracy of evaluation. Geologic elements of trap evaluation have two types , namely trap accumulation and trap quality respectively. The former directly determine whether an accumulation can form in a trap and can be established based on success rate of exploratory wells ; while the latter are mainly used to describe the scale and quality of traps and can be established by using cumulative probability grading methods.