Archived, originally published in March 2018
The platform was located on an old depleted oil field in the Dutch Continental Shelf. Oil production had ceased. The condition of the platform was such that the owner decided to abandon the wells and to remove the platform. Hydraulic workover was identified as the most efficient way to cut the casings and conductor of each well below the seafloor.
The objective was to cut the 13-5/8” casing, the 20” casing and the 30”conductor at 6 meter below the sea-floor and prepare the casings for removal for 11 wells.
- HWU was required in order to deal with the extreme small space present on the platform and the limited load bearing capacity of the platform.
- The cut was made utilizing a mechanical tubing conveyed rotating cutting device.
- Hydraulic cylinders where used to apply pre-tension on the conductor while cutting.
- The 3 casings were retrieved in one lift utilizing the same crane vessel as used to remove the platform.
- Successfully cut all casings and conductors.
- Technical challenges were the eccentricity of different sizes of casing and the interference of loose sand and items travelling from the sea floor into the wellbore by the open cut.
- No support vessel was required during the cutting operation.
- All tubular was successfully retrieved.
- Zero incidents and accidents.
- Operation was conducted to full customer expectation.