State-Of-The-Art Combined Off-Bottom Liner and Lower Completion Systems: Engineering Optimization and Operational Excellence

Abstract The integration of off-bottom liners and lower completions has emerged as a critical strategy in well completion engineering, aimed at mitigating operational inefficiencies and reducing costs. While conventional methods often employ sequential runs, recent advancements advocate for combined operations to streamline workflows. This paper synthesizes industry practices and presents a successful filed deployment detailing the engineering design and methodology workflow with a focus on collaborative planning, advanced modeling, and proactive risk mitigation. Existing research highlights the importance of integrated torque and drag modeling, hydraulic simulations, and drilling fluid optimization in validating combined run feasibility. Single-run strategies significantly reduce operational time by eliminating intermediate trips, with success contingent upon precise wellbore conditioning and mud design (e.g., high-performance fluids to combat differential sticking in high-permeability zones). Pre-job risk assessments, as documented in multiple examples, are critical in anticipating challenges such as fluid losses or stuck pipe. Field deployment demonstrates that combined off-bottom liner and lower completion operations reduced the completion time by 30–50% compared to conventional two-run methods, with typical execution times ranging between 24–30 hours. Key technical and operational success factors identified across examples include controlled running-in-hole (RIH) speeds to minimize downhole friction and ensure smooth deployment. Reliable setting mechanisms, such as dropped-ball-activated liner hangers and open-hole packers, which enhance reliability in complex wellbores. Advanced drilling fluid and cementation engineering designs and real-time monitoring to achieve effective zonal isolation in high-permeability formations. The study highlights that cross-functional collaboration between drilling engineers, completions teams, and rig personnel is critical to balancing efficiency gains with stringent safety standards. Standardized workflows, supported by torque/drag modeling and pre-job risk assessments, have proven instrumental in mitigating nonproductive time (NPT) and fluid-loss incidents.