ECP/DV Tool to prevent gas migration the 9-5/8" x 13-3/8 annulus?
29 August 2009
Hess Libya is drilling a deepwater subsea well that has the potential to experience significant losses when cementing our pay zone behind 9-5/8" casing. Our concern is that if the pay zone is not fully isolated, gas may migrate up the 9-5/8" x 13-3/8" annulus. We are looking for mechanical options for isolating the 9-5/8" x 13-3/8" annulus after the cement job to prevent gas migration.
1. Has any one used an ECP / DV tool in subsea applications and if so, could you share the generalized information on how you functioned the tool and which company supplied the equipment.
2. Has anyone used Swell Packers on 9-5/8" casing x 12-1/4" hole or 9-5/8 " casing x 13-3/8" casing for this purpose? If so, which company provided the equipment and how reliable was the performance of the equipment?
3. Any other mechanical options that the forum would recommend? We are looking at running the 9-5/8" as a liner as well, but this is not our preferred option at this point.
What about an expandables run in the liner string to mitigate this risk?
These exist for such an application that can be set simply by pumping up as soon as plug bumps with cement in place.
There should be little problem coming up with a viable 2 stage job and there are some choices in stage tool/annulus packer type. The well paramaters and conditions would need to be looked at in some detail. The complexities associated with running a 2 stage system on the 9 5/8 sub sea casing or on a liner are similar. Weatherford can supply equipment to do this. A vaible 2 stage system with conventional swell packers or indeed other products that feature swelling element as additional assurance may be a consideration. The best way forward would be a face to face meeting
We (BP Azerbaijan, platform ops) have used swell packers form Halliburton in 9 5/8" x 13 3/8" annuli. However, we may move away from this, as all you are doing is masking the problem - the potential for gas migration to the shoe, and exceeding MAASP at the shoe is still there - you just can't monitor it. If your equipment can handle gas to seabed, it may be better to be able to monitor it. We have one well with a swell packer installed that has annulus pressure - we have still to confirm if this is just trapped pressure, or if the packer has failed.