Pressure Transient Analysis for Vertically Fractured Wells in Tight Stratified Reservoirs: Accounting for Nonuniform Fracture Conductivity and Fracture Face Damage

Separate-layer fracturing is a critical stimulation technique for enhancing productivity in tight stratified reservoirs, yet conventional pressure transient analysis (PTA) models for vertically fractured wells in such reservoirs often overlook the combined effects of nonuniform fracture conductivity (caused by uneven proppant placement) and fracture-face damage (induced by fracturing fluid leak-off). Individual investigations of these two factors have been well documented, but their coupled impacts on PTA responses of multilayer fractured wells remain unaddressed. To fill this gap, this study develops a semianalytical PTA model that simultaneously incorporates nonuniform fracture conductivity and fracture-face damage for each layer of tight stratified reservoirs. The model is derived by coupling reservoir and fracture flow equations and solved via Laplace transformation, superposition principle, and Stehfest numerical inversion. Key findings show that nonuniform fracture conductivity introduces an additional transition flow regime between classical bilinear and linear flow, while fracture-face damage suppresses bilinear flow and extends linear flow, and their coupled effects form a unique diagnostic signature for flow regime identification. Sensitivity analysis reveals that fracture-face skin factor, propped segment length, and propped/unpropped fracture conductivity dominate flow behavior, with more pronounced impacts in high-permeability layers. Field applications to Wells A1 and A2 validate the model’s practicability: it accurately matches field pressure-buildup data, quantifies layer-specific fracture closure and damage, and provides actionable insights for targeted remedial stimulation measures. Related findings provide a unified PTA framework for layer-specific parameter interpretation of vertically fractured wells in tight stratified reservoirs and improve the accuracy of fracturing effectiveness evaluation.