Control Line Isolations on a North Sea Wellhead – Mac-Seal

 Ensuring we are providing robust and efficient solutions is our key focus when supporting our clients.

Our client requested our help to provide an isolation for three control lines which were operating downhole injection valves. We were required to provide a solution that would be reliable and safe, but quick to install so the well could be back online as fast as possible.

Results

When approached by the client, we identified our unique Mac-Seal product to support the isolation of the control lines.

We deployed the product within two hours of arriving on site and, once the product had cured (overnight), the well was brought back online safely with minimal downtime after we carried out our standard testing.

All control lines were vented, and no pressure build up was witnessed, and the tests confirmed that there were no leaks on any of the isolated control lines.

The value-adding, rigless isolation operation saved the well owner from a potentially time consuming and costly workover or long-term suspension.

Challenge

The client became aware of three severed control lines on one well which operate downhole injection valves. The lines were severed at 6,800ft due to high pressure water injection flow, with a reservoir pressure of 3,000psi.

C-77 double block and bleed valves were fitted to the wellhead and control lines.

The client needed a solution that would bring results quickly, whilst still maintaining a focus on quality and safety.

We needed to create an isolation and clear the C-77 block valves of sealant so that essential monitoring and wellhead maintenance could be carried out in the future.

Solution

The control lines in question were flushed with Transaqua HT2 to remove any obstructions to determine if the lines held any problems.

We then deployed 500ml of Mac-Seal into each control line creating a 140ft plug to isolate the lines. A high viscosity fully synthetic grease was deployed behind the Mac-Seal, displacing the sealant past all working parts of the C-77 block valves and tubing bonnet stabs.

The product was then left overnight to cure before the lines were pressure and leak off-tested.