A NEW APPROACH FOR TIGHT OIL RESERVOIR QUALITY EVALUATION USING A COMPREHENSIVE EVALUATION FACTOR

The evaluation of reservoir quality pre-fracturing treatments is one of the most important jobs faced by oilfield engineers. However, reservoir quality relates to the quantitative complicated evaluation of factors for individual members as well as to their comprehensive influence. It is difficult to describe the nonlinear relationship of various factors. A novel and original combination of the analytic hierarchy process (AHP) and grey relation analysis (GRA) method was proposed in this study to solve the problem. First, based on the parameters of the constructed wells, several elements were chosen as appraisal factors. Then, GRA was used to determine the weights of the main factors. Finally, comprehensive evaluation factor (CEF) was applied to determine the classification threshold and evaluate reservoir quality comprehensively with considering the various factors at the same time. The new method was successfully applied to 13 wells of an actual tight oil reservoir in Northeast China and finally the reservoir quality was ranked in order of the CEF. Practical application results demonstrated a good agreement between the measured initial cumulative production and the comprehensive evaluation factor. The new approach can be used to evaluate reservoir quality quickly and economically, the study provides important reference for hydraulic fracturing optimization design.