The Offshore Production System comprises three main components:
* Seafloor Production Tools;
* Riser and Lifting System; and
* Production Support Vessel.
Seafloor Production Tools (SPTs)
Rock is disaggregated on the seafloor by two large robotic machines that excavate material by a continuous cutting process, not unlike coal or other bulk continuous mining machines on land. The Auxiliary Cutter (“AC”) is a preparatory machine that deals with rough terrain and creates benches for the other machines to work. It will operate on tracks with spud assistance and has a boom mounted cutting head for flexibility. The second machine, the Bulk Cutter (“BC”), has higher cutting capacity but will be limited to working benches created by the AC. Both machines leave cut material on the seafloor for collection by the Collecting Machine (“CM”). The CM, also a large robotic vehicle, will collect the cut material (sand, gravel, silt) by drawing it in as seawater slurry with internal pumps and pushing it through a flexible pipe to the Riser and Lifting System.
Riser and Lifting System (RALS)
The RALS comprises a large pump and rigid riser pipe hanging from a vessel which delivers the slurry to the surface. The proposed positive displacement pump is designed and built by GE Hydril (Houston, TX). The pump hangs from a solid vertical (riser) pipe suspended beneath the support vessel. The pipe is deployed to the seabed by a derrick and draw works system on board the vessel.
Production Support Vessel (PSV)
On deck of the production support vessel, the slurry is dewatered. The dewatered solid material is discharged to a transportation barge moored alongside. Used seawater is pumped back to the seafloor through the riser pipes and providing hydraulic power to operate the RALS pump. Discharge of the return water at the seafloor will avoid impacts to the warm surface seawaters, minimizing environmental impact of the operation.
The transportation barges haul the material 50 kms to a stockpile location in the Port of Rabaul.