WAG reinstated in 12 hours
Platelets® seal 0.35mm equivalent outer annulus to conductor leak
- Client Major Operator
- Leak Location Outer Annulus - Conductor
- Location North Slope, Alaska
- Nominal Bore 9 5/8 inch casing
Challenge
A water and gas (WAG) injection well was downgraded to water injection only, following the identification of shallow leak from the outer annulus to the conductor, resulting in annulus fluid discharge to the environment. Costly and time-consuming work would normally be required to excavate and remove the conductor casing in order to patch the leaking casing.
Solution
A set of tailored diagnostic flow tests using Telepath® were carried out to profile the leak, confirming a leak of 0.35mm equivalent diameter. A solution containing specific Platelets®, designed to seal leaks of that size and cope with the environmental conditions they would be subjected to in the coming years, was injected into the system via the annular wing valve. Because of the minimal flow rate through the leak the annulus was charged, closed in and then left to allow the Platelets® to migrate to and seal the leak.
Outcome
The operation successfully terminated the annulus to conductor communication and the well passed an MIT at 1,700 psi to reinstate full service qualification. This was achieved without having to excavate and remove the surface conductor, or pull the tubing and cut and pull the casing.
The upside
The well was certified to resume hydrocarbon injection (WAG) to regain optimum reservoir support operation. Costly excavation workover was avoided and the operation was not dependent on seasonal conditions. The well was reinstated by a simpler and much safer process than excavation and brought back to a serviceable state in a much shorter time frame than conventional processes: twelve hours, compared to six weeks for excavation, the only other alternative approach to repairing the integrity of the well.
