CASE STUDY: Double Success for ISO 14310 V0 HETS Packer/Hanger in Offshore Straddle Application

Two HETS solid expandable packers provide an ISO-qualified gas-tight seal across a casing leak.

THE CHALLENGE

A long-term, fully gas-tight repair of a 9 5/8" casing string was required for an oil and gas producing well on a well in the Norwegian North Sea, to avoid having to plug back and redrill the well.  The well was undergoing completion with gas lift when a leak was discovered. Further investigation established the leak location within the 9 5/8" casing string, in a damaged casing coupling. A multifinger caliper survey also revealed a further area of significant metal loss about sixty metres below the leak site.

THE SOLUTION

Alternatives reviewed included the cutting and removal of the damaged 9 5/8" and using a HETS External Patch to reconnect new casing.  This would have avoided any loss in ID, but the cut would have been made in open hole, which introduced an undesirable level of risk to the operation.

The optimum solution was evaluated as an ISO 14310 V0-qualified straddle (or patch) across the damaged area of 9 5/8"casing with the HETS packer providing to be the only product available on the market to meet the requirements of the application.

• A straddle was constructed by installing two HETS solid expandable packers, one at each end of a seventy-meter long section of 29.7 ppf 7 5/8" casing
• The HETS packer/liner-hanger is qualified to ISO14310 V0 at 5000 psi with simultaneous 200-ton  tension / compression load capabilities.
• The straddle assembly was deployed on drill pipe and located in the 9 5/8" casing using a conventional hanger (without packer) with a PBR assembly above it to act as an entry guide.
• A HETS expansion tool was deployed on drill pipe to successfully  expand each of the two HETS packers
• The straddle was tested in situ to 345 bar (5000 psi) - with a positive seal confirmed

THE VALUE TO CLIENT

• The leak was successfully repaired, thus restoring the original objective of a V0 (gas tight) primary well integrity barrier.
• The use of the ISO 14310-V0 certified 7 5/8"x 9 5/8" READ hanger saved the Operator the considerable cost of redrilling the well, as well as the deferred production this would have incurred.
• The drift diameter of the 7 5/8" patch solution was adequate to run a modified gas lift completion