Pressure Transients Due to Near-Wellbore Screenout

Abstract This study aims to model and analyze pressure transients caused by near-wellbore screenouts during hydraulic fracturing operations. It focuses on characterizing the dynamic response of the well system, the propagation of pressure waves, their impact on surface and downhole pressures, and the role of pressure relief mechanisms. The study adapts the classical water hammer model, considering fluid compressibility and deriving the governing equations from first principles. A proprietary numerical model using the method of characteristics was developed to simulate pressure transients in a 1D discretized space-time framework. Key boundary conditions, including pump performance curves, valve dynamics, and pressure relief valve (PRV) behavior, were incorporated. Sensitivity analyses were conducted to assess the effects of screenout duration, hydraulic fracture location, and PRV functionality on system responses. The simulation results demonstrate that short-duration screenouts produce significant pressure surges that exceed a pressure differential of 6,000 psi at the bottomhole location and propagate to the surface with up to 80% of the peak surge. PRV actuation effectively mitigates excessive pressure increases, while PRV failure can trap high pressures in the well, jeopardizing its integrity. Longer screenout times allow greater fluid loss to the formation, reducing peak pressures and enhancing system stability. The findings highlight the critical role of PRVs in managing rapid transients. In addition, they can be used to establish survival loads caused by hydraulic fracturing operations and the well integrity evaluated using reliability-based design (RBD) acceptance criteria. The work introduces a novel pressure transient model that extends classical water hammer theory by incorporating fluid compressibility, realistic pump and valve dynamics, and time-dependent boundary conditions. By integrating this model into a RBD framework, the study offers a probabilistic approach to evaluating well integrity under extreme yet plausible loading conditions. This methodology provides new insights into the critical role of PRVs in managing screenout-induced transients, ultimately supporting safer well designs.