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The offshore activities in deeper waters have initiated the development of offshore submarines for subsea work. Several concepts have been produced.
A new concept for a work submarine for operations in water depths up to 1500 m has been developed. This is a short range vessel operating from a base close to the field.
The submarine is powered by a closed cycle diesel engine and propelled by pressure compensated hydraulic thrusters. The life support system has a regenerative CO2 absorption plant.
The submarine can rest on the wellhead protection structure and perform tasks ranging protection structure and perform tasks ranging from inspection to module change out and intervention operations. The advantage of the submarine over surface vessels is that it can work close to the subsea site in a calm environment and without the encumbrance of long guide wires and umbilicals.
The offshore activities in very deep waters in the Gulf of Mexico and offshore Brazil gave the initiative to develop an offshore service submarine for 1500 m water depth, the OSS 1500.
The background to this development were two concepts developed earlier:
The Offshore Service Submarine (OSS)designed for personnel transfer to 1 atm. underwater production facilities, to carry equipment to subsea sites and to performdiverless IMR operations on wet wellhead installations.
A carrier submarine for the EUREKA project SUPER SUBSEA (SSS). The submarine trans-ports large streamlined modules attached to its hull by means of special connectors.
The dedicated modules carry equipment or tools to perform tasks on subsea installations.
Both submarines have a payload capacity of 25 to 40 tons, an operation depth of 500 m and an endurance of 21 days.