Novel Technique Applied to Lock Open SCSSV Installed in Monobore Subsea Completion in Deepwater GoM

Abstract

This paper highlights a unique technique used to overcome the specific challenge of locking open a failed-closed surface controlled sub-surface safety valve (SCSSV) in a monobore completion without a landing nipple profile above the SCSSV. The technical details of both the problem (inability to use conventional SCSSV lock open tools) and solution are discussed, with specific focus on the solution hardware and technique applied to deliver the objectives of the intervention. Several techniques were considered and a matrix was developed to weigh the advantages and disadvantages of each. The technique selected utilized wireline to install a through-tubing expandable hanger assembly in the tubing pup joint above the SCSSV, with tubular extensions to "hold open" the flapper. The internal bore of the tubular extensions served as a conduit for the conveyance of the intervention tools required to be deployed deeper into the wellbore. This technique was successfully applied to two different wells to achieve the desired results. The technique described in this paper for locking open a SCSSV is not limited to the monobore completion scenario with no available nipple profile. It is suitable for use on any SCSSV, regardless of the completion type or environment. This technique may prove to be a beneficial alternative when conventional lock open tools are not available or prove problematic in their application.