Permeability Jailbreak: A Deep Simulation Study of Hydraulic Fracture Cleanup in Heterogeneous Tight Gas Reservoirs

Abstract

Ultra-tight gas reservoirs present severe flow constraints due to complex interactions between rock-fluid properties and hydraulic fracturing. This study investigates the impact of unconven-tional capillary pressure correlations and permeability jail effects on post-fracture cleanup in multiple fractured horizontal wells (MFHWs) using high-resolution numerical simulations. A novel modelling approach is applied to represent both weak and strong permeability jail phe-nomena in heterogeneous rock systems. A comprehensive suite of parametric simulations evalu-ates gas production loss (GPL) and produced fracture fluid (PFF) across varying fracture fluid volumes, shut-in times, drawdown pressures, and matrix permeabilities. The analysis leverages statistically designed experiments and response surface models to isolate the influence of rock heterogeneity and saturation-dependent flow restrictions on cleanup efficiency. Results reveal that strong jail zones drastically hinder fracture fluid recovery, while weak jail configurations in-teract with heterogeneity to produce nonlinear cleanup trends. Notably, reducing the pore size distribution index in Pc models improves predictive accuracy for ultra-tight conditions. These findings underscore the need to integrate unconventional Kr and Pc behaviour in hydraulic fracturing design to optimise flowback and long-term gas recovery. This work provides critical insights for improving reservoir performance and supports ambitions in energy resilience and net-zero transition strategies.