Subsea Valve Stem Seal Isolation
Isolation of leaking stem seals on a subsea tree valve Product: Mac-Pac
The Client
A UK-based major oil and gas operator approached KCI with a critical subsea issue. Facing a potential fugitive gas leak from a subsea production wing valve (PWV) tell-tale weep hole, the client required an effective isolation solution to avoid a worst-case scenario of plugging and abandoning the well, which could result in costs exceeding £14 million in loss of production.
The Results
The operation was a success, with KCI’s Mac-Pac deployment immediately isolating the leaking stem seals. This low-cost intervention is estimated to have saved the client between £4 million and £14 million by extending the well’s operational life. The solution effectively stopped gas leakage, lubricated the valve stem, and provided ongoing protection for the gate and seat interface, ensuring smooth valve operation well into the future.
The Challenge
The client sought an innovative solution to isolate a fugitive gas leak from a subsea PWV tell-tale weep hole. The challenge involved addressing the leakage in a manner that:
Prevented further environmental impact.
Required minimal downtime and operational disruption.
Extended the valve’s operational life without compromising functionality.
KCI proposed deploying its Mac-Pac technology into the valve cavity, targeting the stem seal area to energise and lubricate the seals, effectively stopping the external leak. The valve cavity would be completely filled with Mac-Pac to ensure long-term effectiveness.
The Solution
KCI provided a comprehensive solution that included engineering expertise, special subsea deployment equipment, product delivery, and on-site personnel. KCI’s bespoke manifold was attached to the PWV grease injection port, and the deployment tool containing Mac-Pac was connected for operation.
A total of 11 litres of Mac-Pac were deployed into the PWV cavity, completely filling the available space and energising the stem seal area.
Gas bubbles stopped almost immediately upon deployment, and the operation continued seamlessly. Mac-Pac coats the stem when the valve is operated, providing ongoing lubrication and isolation for the seals. This approach ensures long-term protection and does not compromise valve operation or functionality.
Testimonial
“KCI have always provided personable, professional, and value-adding service in both surface and subsea wellhead issues. They don’t just provide a product; they complete the required engineering on each job to ensure the highest chance of success. KCI are interested in helping where they can but will also clearly outline any limitations when planning a job. If you have a leak, we highly recommend giving them a call.” Major North Sea Oil and Gas Operator