Advances in sliding sleeve technology combined with improved coiled tubing services have resulted in the successful completion of an abnormally pressured, multi-zone horizontal producer. An operator was planning to develop a horizontal completion in the Gulf of Mexico and required a design that would successfully address certain unusual reservoir conditions; i.e., the primary zone was abnormally pressured, and below the primary zone, there was a secondary reservoir that could not be accessed unless an additional well was drilled or the initial well depleted and a sidetrack performed.
To enhance the economic and operational feasibility of the completion, the operator needed a well design that would address the above pressure conditions and allow production from either or both zones.
This paper will discuss the methods and equipment that were used to successfully provide the project needs.
The completion configuration that was finally adopted utilized a concentric production string with pre-packed gravel pack screens, an external casing packer and multiple sliding sleeves in the concentric production string to provide the zonal isolation as well as wash-down capability since wash pipe would not be run. Significant in the success of the completion was the use of computer simulation of the coiled tubing operations to confirm capability to provide the required forces, and the use of a new sliding sleeve device that only required 500 pounds of shifting force to operate as opposed to three to five times that amount normally required to shift conventional sleeves. In addition, the sleeve had demonstrated superior operational integrity in conditions similar to those expected in this completion in which shifting forces usually caused premature equipment erosion.
The case history will provide information concerning the development of the completion as well as the actual completion scenario and how the completion design allowed fluid losses to the formation to be minimized during the completion phase.
This success demonstrates the capability to complete in several zones with isolation potential in abnormally pressured reservoirs and in completions with depths in excess of 13,000 ft. The use of advanced coiled tubing techniques and the new sliding sleeves that could maintain operational integrity in extremely corrosive environments enabled the job parameters to be met.
