Fracture-matrix flow diagnostics for CCUS-oriented fractured gas reservoirs: a simplified analytical method and field application

Introduction Fractured gas reservoirs are promising candidates for carbon capture, utilization and storage (CCUS), but their pressure response is strongly affected by fracture connectivity, matrix storage, and near-wellbore effects. Methods A simplified dual-continuum pressure-buildup model was developed to separate matrix-to-fracture recharge, fracture-network redistribution, and near-wellbore pressure relaxation using three exponential components. Results Application to two horizontal wells in a Bohai Sea CCUS pilot block yielded effective fracture-controlled volumes of 2,058.2 and 2,289.1 m 3 and matrix-controlled volumes of 11,039.85 and 11,982.52 m 3 , respectively. Both wells showed consistent attenuation behavior, with rapid near-wellbore relaxation, intermediate fracture redistribution, and delayed matrix–fracture equilibration. Discussion The results indicate that fracture-controlled communication dominates short-time pressure behavior, whereas delayed matrix participation governs longer-term storage response. The proposed workflow provides a practical diagnostic for CCUS-oriented well-test interpretation and pressure-management evaluation.