Don’t get stumped by corrosion: Middle East slot recovery solutions

Author: Ben Griffiths 

Offshore infrastructure owners in the Middle East have long been looking for ways to extend the production of their assets where the reservoir still has life. However, they are often faced with integrity challenges associated with those assets reaching the end of their design life.

If the operator’s platform has not reached its fatigue life end, then instead of involving costly design, fabrication, and offshore installation of a new platform, one of the existing well slots can be recovered by performing a conductor recovery operation followed by a new well installation.

This blog will explore some of the challenges and outline the cost-effective slot recovery methodologies which have been proven over several years with multiple operators in the Arabian Gulf.

Current challenges of slot recovery in the Middle East

Slot recovery enables production to continue after the existing well has ended its useful life due to corrosion at the splash zone or internal completion or casings issues. However, developing a new well from old infrastructure does not come without its challenges.

Corroded conductors and casings

Prior to undertaking any conductor recovery operation, it is imperative to understand the condition of the conductor and internal casings. Corrosion can affect the conductor only or one or more of the internal casings or conductors and casings. Specialist systems and methodologies such as a sacrificial string are required to recover wells with high levels of corrosion, especially when the well has parted at the splash zone.

Availability of records

To assess the condition of the conductors and internal casings, maintenance reports need to be reviewed and inspection performed. The challenge comes when records have been lost over the years due to changes in ownership, storage, and location change. If this is the case, surveys can be conducted at the planning stage to measure the wall thickness of the conductor and casings which will dictate the methodology to recover them.

Platform design

Due to the variety of platform designs with various structural beams, cross members and seabed restrictions, the planning of subsea tooling accessibility to the conductor at the required elevation for cutting is a crucial prerequisite. Prior to any operation where access might be restricted, a ‘clash check’ needs to be performed to confirm or alter the approach to the operation.

Rig space

Rigs and platforms in the Middle East typically come with limited deck space meaning that it can be a struggle to store all equipment to perform slot recovery operations. Sufficient consumables and spares with highly reliable primary equipment can be utilised to reduce the space occupied by backup equipment.