Case Study of a Rigless Intervention for the Completion of an Offshore Multi-String Producing Well Using Slimhole Sand Jet Perforating

Abstract

Abstract Cost effective methods for completing new zones in existing offshore wells present challenges for operators that wish to extend the life of their wells by adding production with new zone completion and stimulation. Workover rigs add significant cost to service operations that often challenge the feasibility of the desired work. Challenges for rigless intervention work include running tools through the existing production tubing for perforating and other functions, having to perforate multiple tubing and casing strings while in the production tubing, and logistical constraints on the platform. This paper examines the completion and stimulation of an upper zone in a Gulf of Mexico offshore well using a commercially viable program with rigless recompletion where a traditional recompletion was not cost effective. The objective of the project was to utilize a rigless intervention with coiled tubing for the perforation and stimulation of an upper zone above a production packer while sand jet perforating through two cemented casings. This paper explores a successful and cost effective method used to complete and stimulate an upper well zone. Factors that added to the complexity of the project include running tools through the production tubing and production packer, perforating a 2-7/8" production tubing Y block assembly, a 7" casing string, and a 11-7/8" casing string with cement in the annular space, and logistics for offshore equipment rig up and operation. Multiple rounds of surface bench testing were performed to refine the perforating process and develop procedures for well completion. This paper identifies the challenges for the operation, frac design considerations, and optimizing well production during the initial flowback. The results of the frac, initial injection, and flow testing are included. Cost comparison between the traditional recompletion and this new approach are also important results that help determine overall success of the project. The project was a success in its ability to achieve the technical goals while also being commercially viable. Without this novel rigless approach, recompletion of this zone would not have been feasible. By completing the new zone, the overall production from the well is increased and the life of the well is extended, maintaining its value as an asset instead of a potential P&A liability.