To overcome the challenges of drilling depleted reservoirs, a new technology was needed as part of a cost-effective solution. An innovation campaign was facilitated by a major oil company R&T (research and technology) department in the North Sea to identify concepts enabling high depletion in drilling through reservoirs. Several concepts were evaluated, and a packer in the drillstring was defined as a necessity by the major oil company. Drilling through depleted reservoirs has become more and more common in operations run by both oil operators and drilling companies, in fields that have matured. Drilling these wells introduces an increased risk for crossflow and losses and a series of mitigating actions have been put in place to obtain an acceptable risk level.

This paper will focus on describing the steps taken to develop a packer that provides a seal between the drillpipe and the production casing, being part of the drilling BHA and spaced out to stay inside the casing. It's large bore through allows high flow rates and deployment of intervention tools through it. By setting the packer, it becomes a qualified V3-barrier, validated as per ISO14310 and/or API11D1, enabling the operator to cement and sidetrack efficiently, saving additional trips and rig time. This successful technology cooperation will help oil operators and drilling companies to expand its capabilities for drilling depleted and complex reservoirs and further increase the overall recovery factor for its mature fields.

Rising to the challenge, means to improve the confidence in drilling with limited drilling window and avoid uncontrolled risks by using a Drillstring Annulus Sealing Packer that when set, provides a seal between the drillpipe and the casing, the packer activation is meant to be the last option in a series of mitigating measures as the wellbore will be abandoned if activated.

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