Successful Coiled Tubing Catenary Cement Packer and SAS Installation in a Horizontal Well for Developing Bypassed Reserves: Offshore Niger Delta

Abstract

Rigless coiled tubing (CT) operations with CT operated from a floating anchored vessel are deployed for well intervention operations where crane limitations and deck loading constraint present multiple challenges for accessing the marginal/bypassed pay in offshore locations. This operation involves operating the CT unit with the reel located on the floating vessel and the injector head positioned on the offshore platform. The CT catenary design was successfully deployed for developing behind casing reserves through efficient zonal isolation, cement packer installation, perforations, and sand control. This paper presents the use of 1.75-in. CT on a 125K unit catenary system in a highly deviated horizontal well (>85°) to develop the shallower reservoir. The well is located on a platform with insufficient deck space and load bearing capacity to accommodate the intervention spread. The through-tubing CT operations involve installation of mechanical isolation plugs, cement retainer (CR)/stinger; tubing punch, cement packer installation, perforation, and stand-alone-screen (SAS) installation. The depleted reservoir interval presents challenges with declining production amidst gas lift support and intermittent production attributed to liquid loading. 152 bbl (2,420 ft) of 15.9-lbm/gal cement packer was installed through CT in the 4 1/2- and 9 5/8-in. casing annulus and 656 ft of cement plug on the CR in the 4 1/2-in. tubing. The use of 1.75-in. OD CT and catenary system effectively overcame the deck space and load bearing constraint of the platform while the 125K unit was used for improved CT reach and higher injector snub/pull capacity. Post-job shut-in tubing and casing pressures, quantity of cement slurry pumped, and extended flow test have proven the success of the design and procedure implemented. The operation was executed successfully using CT compared to the more expensive option of workover rig options for field redevelopment.