Setting environmental cement plug from vessel
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Perigon’s Cement Support Tool (CST) was used by Oceaneering during a campaign in 2018. Oceaneering was contracted by two major North Sea operators to plan and execute an eight well plug and abandonment (P&A) and well severance.
Oceaneering provided a unique solution to set an environmental cement plug in one of the wells. To prevent cement slumping inside the well, it is normal practice to set a retainer inside the wellbore (typically a mechanical plugging device such as a bridge plug) at the lowest elevation the cement plug will be set. However, this method can be both complex to run and expensive due to the one-time use of the component, additional equipment requirements and need for additional personnel offshore.
To avoid such issues, Oceaneering's team of decommissioning specialists (including Perigon) deployed an existing CST in a new way. The CST was placed inside a deployment stinger that was crossed over to a deployment hose. The assembly was run down to setting depth and the team pumped water down the hose and into the stinger, which in turn pumped out the CST tool, allowing it to open and set at the required depth. The tool was easy to use and run from the dynamically positioned vessel, required no additional equipment or personnel offshore, and was effective in operation, allowing the environmental cement plug to be set in the well.
Oceaneering accomplished the work without the use of divers, guide wires or explosives, maintaining its 100% success rate for severing wellheads.
You can read the original case study from Oceaneering here.