Global Marine Systems

The coral reefs of the Pitcairn Islands are in one of the most remote areas of the Pacific Ocean, and yet they are exposed to the impacts of anthropogenic climate change. The Pitcairn Islands Marine Protected Area was designated in 2016 and is one of the largest in the world, but the marine environment around these highly isolated islands remains poorly documented. Evidence collated here indicates that while the Pitcairn Islands' reefs have thus far been relatively sheltered from the effect of warming sea temperatures, there is substantial risk of future coral decalcification due to ocean acidification. The projected acceleration in the rate of sea level rise, and the reefs' exposure to risks from distant ocean swells and cold-water intrusions, add further uncertainty as to whether these islands and their reefs will continue to adapt and persist into the future. Coordinated action within the context of the Pitcairn Islands Marine Protected Area can help enhance the resilience of the reefs in the Pitcairn Islands. Options include management of other human pressures, control of invasive species and active reef interventions. More research, however, is needed in order to better assess what are the most appropriate and feasible options to protect these reefs.

Global Marine Systems and ABB worked together to install the subsea cable, Gjøa, that brings electricity from the Mongstad refinery, north of Bergen, Norway, to the floating production platform in the North Sea. Gjøa is the first floating platform to have power supplied by a direct link from the shore. The installation of the power cable was successfully completed on 17 May 2010 and the cable went live on 11 July 2010. This paper outlines the cutting-edge techniques that were used in the cable installation and which will bring benefits to offshore structure developments, such as wind farms, that will be vital for the next generation of developments.

Since the early 1980's there have been significant advances in remotely operated vehicle (ROV) intervention for effective cable burial and maintenance. The early generation ROVs were primarily designed to undertake an inspection and repair function only and had limited capability for the burial of final splices and repair bights. More recently, the work scope of cable intervention ROV systems has been extended to undertake significant portions of post lay burial of cable systems. This paper charts some of the historical events and advances which have led to a generation of new vehicles which are significantly advanced in technological terms compared to their earlier counterparts. It is however worth noting that many of the old systems still remain in use today and SCARABs I and II are still in use some 13 years since first being built.< >

This paper outlines recent developments which have been undertaken to improve techniques for effective cable burial and protection of subsea pipes. Traditional methods of burial for subsea pipework have involved the use of towed plough systems, subsea dredging units, or mechanical or jetting based trenching systems. Recent vehicle developments as undertaken by BT (Marine) Limited (BT(M)) have embodied new techniques which will allow more efficient solutions for the pipeline owners. New vehicles now offer a hybrid of solutions depending on the local conditions which may prevail. For example, the new BT(M) Eureka vehicle has the ability to interface to four separate burial devices. There is a new advanced dynamic jetting system which maximises available power for efficient trenching. There are two separate mechanical tools; a rockwheel cutter for work in very hard seabed materials, and a chain excavator where very deep burial, in excess of 2m, is required. There is also a jet assisted plough which combines the benefits of water jetting with ploughed systems. All of these burial devices are controlled from the same host vehicle which is fitted with the latest sensing and tracking devices. Product handling is of prime importance and the new vehicle systems operate with either a non-product engagement system during burial, or an auto eject facility which ensures that in the event of hydraulic failure the product is safely ejected from the vehicle. At present the burial vehicles have been designed to handle small diameter rigid pipes and flexibles. However, R&D studies have already proved the concept can be extrapolated for larger diameter pipes.