Casing Hanger Mandrel Isolation with Mac-Seal – Wellhead Seal Isolation  

The Client

We were requested by a major oil and gas operator in the UK to provide an isolation on a Vetco wellhead due to A to B Annulus communication. The well was a gas lift design, and the A annulus gas pressure was responsible for charging the B annulus. 

The Results

We successfully isolated the well, bringing it back online safely. The customer was extremely satisfied with our approach to safety and the efficiency of the isolation. The work we conducted on this asset saved the customer from a potentially time consuming and costly workover and prevented any lost production associated with a long-term suspension of the asset

The Challenge

Severe freezing was causing a significant gas leak in the external body of the 9 5/8” casing spool when venting down the B Annulus. This gas leak was causing ice to develop externally on the wellhead. This challenge meant that the client had to shut the well, resulting in downtime for repairs to be carried out.   

The Solution

We were deployed to provide a solution to the challenges and stop further problems arising in the future. We did this by injecting test medium fluid into the casing hanger assembly to pinpoint the exact leak path. 

 In total, 1.8 Litres of Mac-Seal was injected into the 9 5/8” casing hanger mandrel void to establish the isolation. We then injected 0.5 litres of Mac-Seal (thinnest viscosity) to isolate the split or damaged BT seal assembly. 

 Once the Mac-Seal had cured the 9 5/8” casing, the hanger mandrel void was tested using the A & B Annuli pressures. With full gas lift pressure on the A annulus, the B annulus was successfully vented off with no pressure build-up or external freezing witnessed on the external body of the wellhead. 

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