Adaptive Stress Sensitivity Study of Fractured Heterogeneous Tight Reservoir

Fractured tight reservoirs are characterized by their strong heterogeneity and stress sensitivity. To understand with better clarity the influence of reservoir heterogeneity and fracture stress sensitivity on production, we employed the projection-based embedded discrete fracture model to characterize complex fractures. On this basis, a numerical stress sensitivity model considering matrix and multi-scale fracture heterogeneity was built by using the quantitative characterization model of stress sensitivity, and thus the stress sensitivity curve was obtained adaptively. The simulation results demonstrated that the stress sensitivity of the matrix could not be ignored in highly heterogeneous tight reservoirs because it had a great impact on production in the early stages, primarily with respect to hydraulic fractures. It was noted that the stress sensitivity of reservoirs decreased gradually as the production gradually transitioned from fractures to the matrix. Large differential production pressures in the early stages of production would cause a stress damage in the reservoir which was not conducive to long-term production. Moreover, the distribution pattern of multi-scale fractures with different filling degrees in reservoirs had a direct influence on productivity, as a less filled fracture in larger scale would provide higher productivity. The research results can provide a theoretical basis for rational production allocation and development scheme optimization of fractured tight reservoirs.