Research on Identification Method of Dominant Seepage Flow Channel of Fractured Horizontal Wells in Tight Oil Reservoir Based on Fuzzy Synthetic Evaluation Model

Fuzzy synthetic evaluation method has become increasingly crucial in deciphering reservoir dynamics by using an enormous amount of data that field operators acquire. These data contain valuable information about the subsurface process. Dominant seepage flow channel which can not be effectively evaluated and identified in fractured horizontal well–vertical well combined injection–production pattern is one of the most significant aspects of subsurface characterization in tight oil reservoir which can impact a project success. In this study, we present novel techniques to quantify dominant seepage flow channel by applying fuzzy synthetic evaluation method. First we construct dynamic and static indexes that affect the producing and developing of dominant seepage flow channel based on the characteristics of the relationship between fractured horizontal well and injection–production well. Second combined with the comprehensive fuzzy evaluation theory and the analytic hierarchy process, we build up a system to identify dominant seepage flow channel between fractured horizontal well and vertical water injection well and obtain the weight of the index evaluation to determine the S-type or inverted S-membership of each index function. The validity of using fuzzy synthetic evaluation to determine dominant seepage flow channel is verified by the interference well testing analysis results of fractured horizontal well pairs SP6 in Changqing oil field. The dominant seepage flow channel information based on the above method can provide strong basis for the comprehensive water control scheme of developing tight oil reservoir with water injection.