Drilling deeper wells with high angles are becoming the norm in the Gulf of Mexico. As time passes these wells require some type of intervention. Coiled tubing intervention being an economic option creates new challenges by pushing existing coiled tubing technology to its limits. Deeper holes increases string weights requiring stronger coiled tubing pipe, injector heads and surface equipment. Friction must also be addressed with improved fluid designs for reducing circulating pressures without compromising good solids transport capabilities or temperature stability.
Success of these deep interventions greatly depends upon proper equipment; job design, planning and execution of the plan to improve the original objectives achieved.
Evaluation of the objectives, well details, location concerns, and logistics are keys to designing the right coiled tubing string, selecting proper (BHA) bottom hole assemblies, fluids and procedures in these deep wells.
This paper describes the design, planning and execution of a record-depth job with 1½" coiled tubing in a 25,200 ft deep high-pressure gas well in the Gulf of Mexico. The objective of the job was to clean sand from the well, retrieve down-hole pressure and temperature gauges, and prepare the well for the re-completion with the rig.
Several steps were taken to ensure a successful job: A 28,700 ft 110,000 psi minimum yield strength coiled tubing string was designed and manufactured. A special hydraulically optimized fluid with high solids carrying and suspension capacity and relative low circulating pressures was designed and tested. In depth pre job planning was conducted. All these factors played key roles in success of the job.