Set offshore (North Sea) from a semi-submersible platform without active Heave Compensator, the Patch successfully isolated a leaking coupling.
Saltel Patch successfully isolated a leaking coupling, in a 10-3/4in – 60.7 ppf casing. The patch had to be set from a semi-submersible rig giving no guarantee of accurate positioning at depth, due to the heave. The rig did not have an active heave compensation system available (to maintain the BHA at a constant depth).
A customized (6mm steel thickness) 10-3/4in Patch – 5m long was selected, to maximize the differential service pressure rating. The semi-submersible rig was constantly moving up/down, (no active heave compensator) which would have resulted in an inaccurate positioning of the BHA for each expansion step and in uncontrolled forces transmitted downhole on the Patch and the BHA.
The solution to meet such challenge was to modify the setting process by adding a no-go approximately 60ft above the BHA, landing on the tree wear bushing to position and anchor the Patch. The tools were then POOH, and the distance between the no-go and the setting tool was adjusted for the next steps.
Once positioned at the right depth, the Patch was successfully installed.
A total of 8 expansion runs was performed and a final drift run (#9) was done to confirm the Patch drift ID was >8.75in [222 mm].
Once the Patch was set and drift ID confirmed, the well was pressure-tested. The test was solid: <0.5 psi loss per min, versus 3 psi/min before the Patch setting.