Building on a track record of previous gas shut off (GSO) successes Welltec Angola recently completed another GSO along with separate water shut off (WSO) operation. The purpose of the recent operation was to install a multi-segmented straddle packer isolation system in the same well but over a completely different interval. The GSO system, consisting of five packers and 13 straddles, was 482 ft long whereas the WSO system had a length of 295 ft and was made up of three packers and eight straddles.
This most recent operation required 30 consecutive runs in the hole to build the two straddle packer isolation systems. The first and deeper isolation system was installed across the water entry zone; the second and shallower isolation system was installed across the gas entry zone of this high profile well. Each operation saved the operator a potential side track, costing in the range of $50 to 60 million.
To date, Welltec Angola, working with our service partners, has performed four GSO installations for this operator with a combined total of 80 runs. The stellar production results and outstanding service quality have led the operator to commit to another six to eight similar GSO/WSO operations over the next 12 months.
The successes of these operations has become paramount to both the operator and the National Oil Company. They have created substantial production increases, huge cost savings and dramatic decreases in deferred production. Another benefit is the OPEX cost savings from the facilities to handle the produced gas and water only to have to re-inject them into another well.
A complete case story of the first well intervention is available here .