Five questions to ask when considering a slot recovery operation
1. Why is this well underperforming?
There are several techniques that may enhance a well’s recovery rates more cost-effectively than slot recovery, including workover and stimulation.
2. Which part of the reservoir should be entered?
The location, trajectory, final diameter and length of a new well can have a major bearing on its capital and operating expenditure. On a practical level, well trajectory could also impact the viability of a slot recovery from the point of view of the location of the target slot and potential access issues.
3. Can the new conductor be deflected and driven to depth at this location?
A significant curvature will be imposed on the new conductor as it kicks off the whipstock. Without sufficient control, the forces generated during the driving process could destroy the existing well, whipstock or pipe. It is essential that the forces required to deflect the conductor be established.
4. How will the proposed slot recovery impact on the existing facility?
Additional production at an ageing facility can, on occasions, lead to operational difficulties. For instance, the facility may have insufficient capacity for processing, separation or power generation for the new load. Additional flow-assurance chemicals may be required. Pumps may need updating. Deck space may be at a premium.
5. What return on investment can be achieved?
Economic analyses call for an in-depth evaluation of many factors, including the costs of abandoning the well, pulling out the conductors, redrilling and deviating the well, and also the production rate forecasts. Production constraints, mechanical or structural limitations and the production swing must be used in any calculations.
6. Well abandonment and slot recovery – rising to the challenge
The first activity on location is the permanent plugging of the old well and recovery of the conductor. The conductor casing and the inner strings of cemented-together casings must be cut, removed and laid out before the well can be cemented; this is a highly challenging phase.
Claxton brings a long history of offshore experience to the table: a heritage that includes the first-ever rigless platform well abandonment in the North Sea and a suite of leading-edge equipment such as:
- RAPIER™ tubing bandsaws for rapid severance of tubing joints
- RAPIER™ casing bandsaws to enable multiple casing string recovery
- Drilling and pinning machines to secure multiple casing strings
- SABRE™ abrasive-jet cutting systems for single-pass internal cutting of conductors
- Hydraulic-jack or torsion-based systems for verifying deep casing cuts
- Fast-track design of cost-effective bespoke interfaces to facilitate rigless conductor recovery.
Crucially, access to this equipment means the entire operation can be carried out without resorting to a drilling rig – meaning recovering the platform slot can usually be achieved in an extremely cost-effective fashion.
Slot Recovery Case Study Pack
Discover how Claxton’s engineers, machinery and methods have assisted with slot recovery operations all around the world in our case study pack.