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.
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.
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.
How to achieve a successful slot recovery
Asset owners in the Middle East demand quick, safe, and cost-effective slot recovery projects. The key to achieving a successful outcome is to have facilities, local crew and high quality regularly maintained equipment available to call off from local facilities, all supported by pre-planning and engineering.
Claxton, a Cutting and Decommissioning brand in Acteon’s Energy Services division, has developed bespoke solutions to tackle the challenges associated with slot recovery operations in the Middle East. Claxton applies its extensive track experience record in this region and locally based crew and assets with engineering competence to meet the market demands.
How bespoke tooling can be used
With the industry’s drive for operations to become more efficient, Claxton has developed systems that combine two tools to enable the recovered conductor to be drilled and cut at the same time. This all-electric tool reduces the combined cut and pin time from one and half hours to thirty minutes.
To address the space limitations of rotary tables, Claxton has also developed internal lifting equipment which is proven to lift the weight of the well configuration through the restricted opening of the rotary table. Without this equipment, the asset owner would have to request an additional fishing/casing company to provide many sizes of ‘casing spears’ to spear the innermost casing and retrieve it to the rig floor.
The conductor deflector tool is another example where Claxton has developed a bespoke solution to enable new wells from existing infrastructure. The tool is used to absorb the lateral forces of a new conductor being deflected without adding these forces to the platform structure.
Wealth of experience
Since 2010 Claxton has been successfully performing conductor recovery operations in the Arabian Gulf. Each conductor recovery is different due to missing records, level of corrosion, platform design, or lack of rig space, which has enabled Claxton to develop a variety of innovative methodologies to address the challenges outlined in this blog.
How to start planning your project
Based on Claxton’s project experience, early engagement with the relevant parties ensures that the challenges of the recovery situation are fully understood, and operator deliverables are met in a safe, efficient, and cost-effective manner.
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