Modeling Transient Pressure Behaviors of Multi-Fractured Horizontal Wells in Multilayered Tight Gas Reservoirs with Crossflow and Stress Sensitivity
摘要
Tight sandstone gas reservoirs are characterized by heterogeneity and multi-layers, and multi-stage fracturing horizontal wells (MFHWs) are commonly adopted to achieve efficient exploitation. The inter-layer cross flow and stress sensitivity during production make it challenging to accurately characterization of the pressure behaviors of MFHWs. This work presents for the first time an analytical model to investigate the transient pressure behaviors of MFHWs in stratified tight gas reservoirs, incorporating the vertical heterogeneities of layer properties, cross-flow between adjacent layers, and the stress sensitivity. The point-source function, Laplace transformation coupled with Pedrosa’s transformation and perturbation technique are adopted to obtain the analytical solution of transient pressure responses. The proposed model is validated against a commercial software designed for transient pressure analysis, and the transient pressure behaviors of MFHWs in multi-layered tight gas reservoirs are analyzed. Sensitivity analysis reveals that larger cross-flow coefficient causes an earlier start of the crossflow regime in the transient pressure behaviors. The influence of stress sensitivity is more pronounced during intermediate-time and late-time productions. The model and corresponding conclusions can be used to interpret pressure data more accurately for multilayered tight gas reservoirs with crossflow and stress sensitivity and provide more accurate dynamic parameters which are important for gas reservoir exploitation.