Innovative Technologies Deliver Operational Objectives in a Multi-Well, Ultra-Deepwater, Managed Pressure Drilling and Completions Campaign

The deepwater development field in the western Gulf of Mexico (GoM) presents an array of complex challenges for ultra-deepwater drilling operations. The four well campaign was particularly challenging due to extreme water depths, remote location, well trajectory and a narrow pressure environment, 350-100 kpa (50-150 psi), for extended reservoir laterals. The authors highlight the use of innovative technology employed to drill and complete wells in the western GoM deployment, coupled with the first-ever use of controlled mud level (CML), managed pressure drilling technology in the Gulf of Mexico. The approach of selecting the fluid systems to achieve the objectives and the use of hydraulics modeling software with CML modeling capability in the design, planning and execution phases of the project allowed for fluid design optimization. The results were a successful drilling and completion campaign managing multiple fluids systems and operations on an ultra-deepwater, dual-activity drill ship in water depths more than 8,500 ft (2,591 m). The authors discuss the initial use of a low equivalent circulating density (ECD), flat-rheology synthetic based fluid (SBF) designed for narrow margin drilling applications and the transition to the deployment of a newly developed high-performance water-based mud (HPWBM) optimizing the operations to drill the intermediate intervals for final two wells. The authors also will discuss use of the reservoir drill-in fluid (RDF) and solids-free screen running fluids (SF-SRF), designed specifically for use in these open holes, gravel pack completions at hole angles upwards of 90°. Operational efficiencies derived from use of these fluids include ECD management, hole cleaning, directional performance, reduction in downhole losses, and the elimination of non-productive time (NPT) in a narrow margin environment with no loss of rate of penetration (ROP). Additional efficiencies include the seamless transition from derived from use of water-based fluids for drilling and completion phases. Use of the CML technology allowed for precise control of the hydrostatic pressure on wells that previously would not have been technically feasible to drill or complete. The novel use of the newly developed HPWBM on this campaign enabled reduced health, safety and environmental (HSE) exposure impact, increased tank and rig cleaning efficiency, and the elimination of a wellbore cleanout run since the entire well was drilled with only water-based fluids. The fluids were successfully employed in the four wells drilled and completed in a managed pressure environment utilizing CML technology.