BOP Tethering and Wellhead Fatigue Mitigation
The management of wellhead fatigue issues has been an emerging issue for operators with the advent of Blow Out Preventers (BOPs) that are increasing in size and weight, and as drilling times become longer. Accordingly, new well designs for high cost wells have been re-engineered to mitigate the increased potential for fatigue arising from these heavier BOPs.
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A tethered BOP Wellhead Fatigue Mitigation System reduces risk by restricting the motion of the BOP stack above the wellhead, substantially minimising cyclic stresses on the wellhead and extending the fatigue life.
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A BOP Tethering and Suction CAN spread.
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Installing a BOP Tethering Suction Can on the seabed using an ROV.
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A freshly minted Suction CAN prior to deploying on a P&A operation.
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Loading out an ICON suction CAN.
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Installing a suction CAN from an AHT.
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ROV screen shot of suction CAN fully embedded.
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BOP tethers via suction CANs can be deployed very close ot existing subsea infracture without compromising integrity..
The management of wellhead fatigue issues has been an emerging issue for operators with the advent of Blow Out Preventers (BPOs) that are increasing in size and weight, and as drilling times become longer. Accordingly, new well designs for high cost wells have been re-engineered to mitigate the increased potential for fatigue arising from these heavier BOPs.
Prior to this new generation of heavier BOPs, wells were primarily drilled with smaller BOPs with less robust conductor designs that intensify an already potentially problematic condition when endeavouring to interface with newer generation BOPs.
In both cases, there are times when wellhead fatigue mitigation strategies can significantly reduce these risks.
A tethered BOP Wellhead Fatigue Mitigation System mitigates these risks by restricting the motion of the BOP stack above the wellhead, substantially minimising cyclic stresses on the wellhead and extending the fatigue life.
Depending on the specific configuration of the riser and wellhead, analysis has shown a tethered BOP Wellhead Fatigue Mitigation can deliver an improvement of 25 to 1000 times from the original unmitigated wellhead fatigue life.
No modifications to the wellhead or casing string are required as they are all performed to the BOP outer frame on deck.
Another advantage a Tethered BOP Wellhead delivers is an increase to the limits of the marine watch circle above the wellhead.
In shallow water watch circles can be very restrictive and can approach the station keeping limits of dynamic positioning (DP) systems. A Tethered BOP Wellhead allows for a larger watch circle and decreased reliance on the DP station keeping performance.
Bowing of the wellhead from tangential offset of the MODU due to drive off/drift off loads are reduced by factors of 3 to 4, meaning safer operations and reducing the reliance on dynamic positioning.
ICON provides a turn-key solution to BOP Tethering that includes:
- Overall Project Management
- Engineering & Design;
- Geotechnical assessment/s – with market leading local partner
- Optimised field layouts
- Liaison with riser analysis contractor
- Tensioner specification and load analysis – with market leading partner/s BOP Interfaces
- Installation and Operations Procedures / Manuals
- Procurement and Delivery
- Logistics (if required)
- Operations and Maintenance, including offshore support
ICON is not just a supplier of the equipment, but offers the complete package to clients.
ICON’s value extends beyond ex-works delivery, and can assist with:
- Vessel sea-fastening for ease of deployment
- Ex-works logistics to client nominated Quayside facility
- Management of Quayside activities loading the vessel
Suction CAN geotechnical design model for a BOP Tethering system.
Click here for Suction Can and BOP Tether spread rental details
