Successful High-Angle Through-Tubing Cement Packer Deployment and Reperforation Using Coiled Tubing: Offshore Niger Delta

Abstract Most economically feasible production optimization plans for brown fields include deploying rigless technologies for accessing reserves originally considered marginal and were, therefore, bypassed during the early stages of field development. Because these bypassed reserves were not considered significant, most of the wells were completed leaving behind potentials above the production packer that were not considered economically recoverable. Within the Niger Delta mature fields, a greater percentage of the remaining recoverable reserves have been overlooked as bypassed hydrocarbon volumes. Redeveloping the bypassed pay in highly deviated high-angle wells presents challenges, and accessing them usually necessitates pulling the tubing through a major rig workover. Such operations use far greater resources than rigless well interventions offshore and can often consume unaccounted for time in milling. Rigless through-tubing cement packer technology and reperforations have been deployed to access marginal/bypassed pay in mature fields. Cement packers typically provide a means of zonal isolation of the last reserves in an existing wellbore above the production packer. The success of these operations has historically been low in highly deviated wells primarily because of poor cement bonding in the annulus between the tubing and production casing and issues with pulling the coiled tubing (CT) out of hole while maintaining differential pressure between the wellhead and casing head pressures. This paper presents the successful deployment of through-tubing cement packer rigless reperforation without sand exclusion for accessing bypassed hydrocarbons in high-angle (72 to 80°) deviated wells through CT, offshore Niger Delta. This paper reviews design considerations and precautions for placing the high-angle cement packer through CT as well as production results. Post-operation shut-in tubing and casing pressure, quantity of cement slurry pumped, and extended flow testing have proven the success of the design and procedure implemented.