An Analytical Approach to Optimize Shut-In Time Based on Oil Saturation Rebalancing for Production Performance Improvement

Abstract To address the challenges of inconsistent shut-in performance, unclear effectiveness, and uncertain optimal duration in fractured reservoirs, this study develops an integrated numerical model coupling fracture closure, oil-water imbibition, and fracturing fluid retention during the fracturing-shut-in-production sequence. Model validation confirms its reliability in characterizing fluid migration and determining optimal shut-in duration. Key findings include: (1) Shut-in fluid migration exhibits temporal stage characteristics—fracture closure, imbibition replacement, and energy equilibrium—spatially correlated with fracture complexity; (2) While extended shut-in (30–45 days) enhances initial production through capillary imbibition, prolonged fracturing fluid retention exacerbates oil-phase permeability damage, necessitating balanced duration optimization based on cumulative oil gain; (3) Incorporating operational constraints, the "fracturing + shut-in duration" metric is proposed to reduce well-to-well variability while improving time efficiency. This work establishes an evaluation methodology and workflow for post-fracturing shut-in optimization in volume-fractured horizontal wells.