Teekay Petrojarl Banff Reinstatement Project
Axis Energy Projects was contracted by DOF Subsea to provide engineering and operational procedures for the Teekay Petrojarl Banff FPSO reinstatement project. This included the disconnection, laydown and reconnection of the STL Offloading Buoy, Riser Installation Analysis and Project Engineering on the Banff FPSO.
The STL Buoy Reinstatement
The STL Reinstatement Project was divided into two phases, the first of which took place in the summer of 2013 and focused on the disconnection and tow in of the STL Buoy. This commenced with disconnection of the 12” flexible riser from within the STL Buoy so that it could be laid down on the seabed and secured in place with mattresses. Axis Energy Projects provided full structural engineering analysis and design, prepared rigging drawings, equipment lists and deck layouts, developed the operational procedures and storyboards, and presented the procedures to the pre-op HIRA.
Following the laydown of the riser each 120mm chain was severed using a diamond wire cutter, with the free end of the chain and mooring wire being recovered to deck, leaving the lower wire and lower chain segments undisturbed. Axis Energy Projects personnel were also responsible for writing the procedures, specifying the equipment for cutting the 120mm chains and the 113mm wires. The Buoy was then prepared and transported to Invergordon for refurbishment.
The final phase of the project mobilized in April 2014 and encompassed the full reinstatement of the STL Buoy in the field along with new upper wire segments of its mooring lines and reconnection of the 12” flexible riser. A 75Te clumpweight was utilized to pull down the Buoy and generate slack in the mooring lines for reconnection. The first 3 mooring lines were connected on deck with the remaining 5 being connected on the seabed by ROV and hydraulic H-Link connection frame. Axis personnel were able to optimize the function of this hydraulic tool so that it was more tolerant of the weather conditions and ROV friendly. Like the first phase, this phase was completed without incident and with days to spare.
FPSO Riser Installation Analysis
The Riser Installation scope of work was carried out over the winter of 2013/14 and included analysis for the riser pull-in to the FPSO, buoyancy module installation and laydown of the riser second end. Static analysis was performed to determine the correct procedure for each operation. This was followed by dynamic analysis to determine the limiting seastates based on the critical cases from the static analysis. Lay tables were derived to show the necessary combination of vessel offset, riser and winch wire lengths.
Along with the Riser Installation Analysis, Axis Energy Projects also provided personal to review, coordinate and harmonise numerous riser deployment procedures as well as gathering evidence and preparing reports. Throughout the Banff Reinstatement Project Axis Energy Projects provided onshore and offshore support and senior project engineers. The need for significant and lengthy changes during the each phase of the operation were mitigated through the effective use of pre-mob HIRAs, planning and detailed procedures. The Petrojarl Banff FPSO was returned to station and recommenced production in July 2014.
Deliverables: STL Buoy Reinstatement
- Provided structural engineering support, analysis & design.
- Analysed the laydown, wet storage & reconnection of risers using Orcaflex.
- Designed the foundation for subsea winch including rigging, & worked with winch supplier to ensure winch was suitable for project.
- Specified equipment, prepared RFQs & reviewed bids.
- Prepared rigging drawings & equipment lists.
- Prepared deck layouts & seafastening.
- Oversaw the fabrication of equipment & expedited completion when mobilization dates changed.
- Oversaw fabrication of tooling & guide frames & arranged SIT of mooring chain reconnection equipment.
- Developed procedures & storyboards & presented them at HIRAs.
- Offshore & onshore support providing senior project engineers.
- Reviewed & enhanced customer supplied equipment to avoid operational delays offshore.
Deliverables: FPSO Riser Installation Analysis
- Provision of static & dynamic analysis & preparation of lay tables for the pull in of risers to the FPSO I-tube including installation of buoyancy modules & laydown of the second end.
- Analysis & seafastening design of the Riser Reel Tracks & Towers.
- Designed 90Te clumpweight for riser initiation & controlled pull down of buoyancy (& STL Buoy).
- Design of Grillage & Bumperbars for the offshore deployment & recovery of 90Te Clumpweight.
- Design of dismountable skidding frame for FPSO riser winch.
- Review, coordination & harmonisation of numerous riser deployment procedures.