A Parameter Optimization Workflow of Fractured Horizontal Well in Unconventional Reservoir: Case Study

Abstract

Abstract The application of fractured horizontal wells has become an effective mean to improve the ultimate recovery of tight gas reservoirs. However, there still lacks of a complete and systematic approach to optimize the fracturing-treatment parameters of multi-stage fractured horizontal wells (MFHW), like fracturing-fluid volume, stage spacing, and proppant volume. In this paper, a transient flow model of horizontal wells in tight gas reservoirs is developed with considering complex fracture network generated by large-scale fracturing. Based on this model, an optimization workflow of fracturing-treatment parameter is presented by coupling rate transient analysis, performance forecast, and multivariate nonlinear fitting method. First, the reservoir/fracture parameters are evaluated using the rate transient analysis. Then, performance forecasts are performed by using the transient flow model. With multivariate nonlinear fitting, a relationship model between production volume and fracturing-treatment parameters is found, including average fracturing-fluid volume per stage (AFV), average stage spacing (ASS), and average proppant volume (APV). To demonstrate the reliability and practicality of the parameter optimization workflow, a field case is studied. The results show that in the field case the optimal AFV and ASS are respectively ranging from 900-1100 m3 and 60-120 m, while the optimal APV is ranging from 200-500 t. In this situation, the average cumulative gas production can reach 2.73×108 m3, increasing by an average percent of 28.26%. This study provides a new and feasible way for parameter optimization of fractured horizontal wells in tight reservoirs.