The Well Drilling Geologic Risk Evaluation Methods in Jiyang Depression:An Example of Glutenite Bodies at Steep Slope Belt

Jiyang Depression has entered into subtle reservoir exploration stage at present. The main geological risks in present exploration include the identification of different type subtle reservoirs, judgment of hydrocarbon existence and the scale of the same type subtle oil and gas reservoirs. In this paper, well drilling geologic risk evaluation methods have been established for the key glutenite bodies at steep slope belt. Through analysis of the geologic conditions for HC accumulation and the failure reasons for well drilling, the geological risk analysis has been conducted, the main controlling factors for HC accumulation have been summarized, and the geological factors for geological risk assessment have been determinated. Through analysis on the geological conditions and statistical analysis, the grade scale of the geological elements has been established. With the success rate of exploration method, the weight coefficients have been obtained, and the geological risk evaluation criteria have been established. These geological risk evaluation criteria have been proved with exploration wells drilled in 2009, and the evaluation results match well with the drilling results, with matching rate of 80%.