Shell U.K. Limited Teal P1 subsea well was completed in July 1996 with a peak flow rate of 40,000 bopd. During the completion phase there were a number of problems and failed attempts in setting the production packer, which subsequently resulted in debris in the wellbore. To prevent this debris damaging the turret assembly in the FPSO, a debris barrier, consisting of a perforated tail pipe and a 3 ½” bridge plug, was installed in the production tubing 50 ft below the TRSSSV. Problems with the TRSSSV and the subsea tree valves resulted in a completion workover being scheduled. Prior to pulling the production tubing, the A-annulus was pressurised to 3500 psi to reduce the differential pressure across the tubing. At 2850 psi there was a sudden loss in pressure indicating a leak in the outer casing string. The workover was suspended and the well left in a safe condition. Planning for a full abandonment was then implemented.

Two abandonment options were possible: remove the debris barrier and abandon the well using coiled tubing, or drill a secondary well which would intercept the reservoir section of Teal P1 allowing it to be isolated. The coiled tubing option was only given a 30% chance of success, but due to the potentially large cost saving if successful, this became the primary option. The main hazard in the coiled tubing intervention would be removing the 3 ½” bridge plug from the debris barrier which had been in place for over 12 years. To address this a number of onshore trials were carried out to determine if the plug could be milled if fishing was not achievable.

After a total of 52 coiled tubing runs with a variety of customised BHA's, the requirements of the coiled tubing intervention were met allowing full abandonment of the reservoir. This paper discusses the well history, requirements of the coiled tubing intervention, the onshore trials and the offshore operation.

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