双重机制解锁平台释放难题

Delmar Systems successfully completed an 8-line disconnect of the mooring system on Seadrill’s West Phoenix semisubmersible drilling rig on the UK Continental Shelf. The rig disconnection was performed in two and a half hours without needing AHTS vessel assistance. The West Phoenix is currently under contract with Equinor for a three well campaign, all of which are using Delmar’s Releasable Anchor Mooring System.

Delmar’s RAR Plus is a dual-release action (acoustic and mechanical) rig anchor release. The RAR Plus allows for immediate rig transit after release with the RAR Plus’ nested in their trigger sleeves against the rig fairlead. This eliminates the weather window requirement that is typical for AHTS operations during a traditional rig disconnect. 

“We had the privilege of being the first to perform a successful disconnect in the North Sea without support of AHTS vessels,” Jan Petter Leirvåg, Equinor’s Senior Consultant- Rig Move Operations, said. “We are always looking for improvements when it comes to safe and efficient operations on our rig moves and the RAR Plus is definitely an improvement. The West Phoenix will have the Delmar RAR Plus’ on three wells to begin, and after a successful test period, we will look for opportunities across our rig fleet. Good cooperation with Moray Systems and Delmar has made this a true success.”

“We are excited to introduce our Releasable Anchor Mooring System to the North Sea and save our customers significant rig time and vessel time during rig disconnections using RAR Plus technology,” John Shelton, Delmar System’s Vice President of Technical Services, said. “We look forward to the continued success of this campaign with Equinor and many future ventures in the North Sea.” 

The first disconnect of the three well program was performed using group line releases of two lines, two lines, and four lines. Equinor’s three well campaign is scheduled to continue through Q3 2019. 

RAR Plus™- Leading the Releasable Anchor Revolution

• Increased Minimum Break Load (MBL) for increased robustness
• Increased release load rating for greater flexibility
• Independent backup mechanical release for ultimate reliability
• Remote direct and indirect tension monitoring for enhanced risk mitigation
• ABS and DNV Certified Mooring Component
• Trigger-sleeve nesting capability for faster rig disconnects not dependent on AHTS vessels

The next generation of the RAR is the RAR Plus™, and it comes with some impressive improvements to an already proven device with 35+ years of history. Perhaps the most important development is the addition of a mechanical backup release feature, which ensures the ability to release the moorings on the very small chance that the remote acoustic transmission fails to actuate the RAR. The backup mechanical release bypasses the acoustic, electronic, and hydraulic systems in the RAR Plus™, and it can be actuated by either the rig itself or with a nearby support vessel.  After acoustic or manual activation of the release, the RAR body can be pulled taut with the rig’s winch and nested with the trigger sleeve against the rig’s fairlead. With the RAR securely nested, the rig can sail away without needing to rely on AHTS vessel operations that can delay a rig move if weather downtime or vessel breakdown issues occur.

The new device also has a significantly increased minimum break load (MBL) of 900 tonnes, so that the RAR Plus™ isn’t the limiting MBL component even in systems with high strength components in their mooring lines. The release load rating has also been increased to over 360 tonnes, allowing for disconnection at higher line tensions. Every RAR Plus has dual design and manufacturing certifications from both ABS and DNV ensuring the utmost scrutiny on design, manufacturing, and testing processes for every single unit. 

The RAR Plus™ can also be equipped with an acoustic telemetry system with integrated sensors providing real-time continuous monitoring of local line inclination, depth, and, strain. The sensors inside the RAR Plus and topside processing unit will communicate through acoustic modems and proprietary algorithms to display both direct-measured and indirect-calculated line tensions onboard the rig in real-time. This data is independent of the rig’s existing load cell tension readings. A user-friendly graphical user interface (GUI) will display valuable data for onboard personnel to use during mooring activities and for the duration of the drilling campaign. The data stream can also be integrated with 3D catenary monitoring systems, providing ultimate risk mitigation for mooring in congested fields. Of course, all data will be saved in both the topside processing unit and locally within the RAR Plus™ memory for any desired post-analytical purposes. The telemetry system is optional and can be easily removed for applications that do not require enhanced risk mitigation measures.