Riserless Subsea Completion with Disappearing Plug Technology

The installation of a subsea tree from a floating drilling rig is one of the most complex and time-consuming portions of a deepwater subsea well completion. Removing subsea tree installation from the rig "critical path" would yield a step-change reduction in the time and cost to complete a subsea well. Disappearing plug technology holds the key to achieving this improvement. Regulations (and good practice) dictate the use of a plug set in the tubing hanger of a completed well to provide a barrier to well flow. Until recently, most subsea trees were installed from the drilling rig on a completion riser, after the BOP stack and marine riser were removed. The completion riser also provided the conduit to remove the tubing hanger plug. "Disappearing plug" technology eliminates the need for the completion riser and drilling rig during subsea tree installation because it acts as a well barrier, performing the same function as the tubing hanger plug, until it is opened remotely from the host facility. This paper discusses the application of disappearing plug technology to a subsea project, the synergies created between downhole completion operations and subsea installation activities, and the resultant time and cost savings.