Well Abandonment: DHSV Line Block UK Subsea Wellhead with Mac-Seal 02
The Client
Industry: Oil & Gas
Location: United Kingdom
Operator: Confidential UK Subsea Operator
The Results
A hydraulic system leak at the DHSV feed line was successfully isolated, preventing further hydrocarbon discharge into the sea. The isolation was tested at 2100 psi and passed successfully. A second pressure test carried out 24 hours later also confirmed a good seal.
The successful isolation allowed the planned well abandonment to continue safely, with no environmental risks. The operator was extremely satisfied with KCI’s safe, effective, and efficient isolation solution, ensuring environmental protection and operational success.
The Challenge
A subsea wellhead in the UK sector faced an issue during a planned well abandonment operation. The downhole safety valve (DHSV) feed line was leaking at a hydraulic coupling on the subsea tree, which had backed off, resulting in hydrocarbon fluids leaking into the sea. The wellhead retrievable downhole safety valve had already been recovered, leaving the DHSV control line system open to the tubing bore. The operator needed a solution to isolate the leak at the loose connection to prevent further environmental discharge and allow the well abandonment to proceed safely.
The Solution
KCI engineered a customised solution using Mac-Seal, bespoke tooling, and technical expertise to isolate the leak in the subsea wellhead. The solution involved deploying Mac-Seal into the control line hot stab, using a remotely operated vehicle (ROV) to block the hydraulic system leak and create an isolation.
Steps taken:
KCI’s team deployed Mac-Seal through the control line hot stab, using an ROV to place the sealant at the leaking hydraulic coupling accurately.
Mac-Seal successfully blocked the hydraulic system leak and was fully cured within eight hours, forming a robust isolation.
After the Mac-Seal was fully cured, the isolation was tested by raising the wellbore pressure, which was in communication with the DHSV control line at the surface. A positive pressure test of 2100 psi confirmed the isolation's success.
Conclusion
KCI's expertise ensured not only the prevention of further hydrocarbon discharge but also the seamless continuation of the abandonment process. With rigorous testing confirming a robust seal, the operator achieved their objectives without environmental compromise. This case highlights KCI's commitment to safety, efficiency, and environmental stewardship, delivering reliable outcomes in critical offshore scenarios.