Advancing Well Integrity Preservation in Workover Rig Intervention Via Instrumented Coiled Tubing and Through-Tubing Inflatable and Retrievable Packer Deployment: A South Kuwait Case Study

Abstract

Abstract The purpose of this paper is to present a case study of a pioneering step taken in restoring well integrity for workover rig intervention through the utilization of instrumented coiled tubing (CT) and through-tubing inflatable and retrievable packer (TTIRP) in South Kuwait Field. In this particular instance, mechanical constraints at the christmas tree tubing hanger hindered the ability of the operator to install the blowout preventer (BOP) of the workover rig through conventional means. As a result, a custom-fit approach was implemented to enable the required number of pressure barriers to intervene the well. The intervention approach employed the use of instrumented CT for barrier restoration, well killing and temporary well suspension. CT real-time downhole telemetry was utilized to ensure accurate placement and setting of the TTIRP within the production tubing. Once the packer integrity was pressure tested in both directions, CT was disconnected, and a sand plug followed by an acid soluble cement plug were placed on top of the TTIRP. Upon confirmation of cement plug integrity, the workover rig was utilized to install the BOP for intervention. The instrumented CT was then rigged up and run back-in-hole to clear the cement plug, circulate the sand out, and retrieve the TTIRP to the surface. The candidate well where this innovative intervention workflow was implemented had a maximum potential wellhead pressure of nearly 1,500 psi and a plug-back true depth (PBTD) of 4,000 ft. The well was completed with 3 ½-in. production tubing set close to 3,500 ft MD and 8 5/8-in. casing until PBTD. An e-line through-tubing puncher was carried out in the production tubing before the first CT run to enable circulation of killing fluid. The TTIRP setting depth was conditioned via instrumented CT and high-pressure rotary jetting tool, resulting in a shut-in wellhead pressure near zero psi. The results of this innovative intervention workflow were substantial, with an estimated saving of 195,000- bbl in deferred production (as the well was shut-in for at least 10 months). The lessons learned from this case study can now serve as a reference for operators in the Middle East with wells that present similar challenges.