The next generation of subsea inspection, maintenance and repair (IMR) vehicles are drones capable of operating both autonomously and under human control. Many different technologies are required for the drones to as an IMR platform and operate in and around a subsea templates. The overall objective of this thesis is to investigate how subsea template can be altered to better facilitate drones and reduce life cycle cost.
A literature review was performed to identify good design characteristics that can reduce life-cycle cost of subsea templates. The trends identified were use of modular designs, standardized interfaces and hybrid GRP and steel structures. These characteristics can allow for easier field- expansion or re-configuration, reduce the size for required installation vessel and lower installation weather dependency.
It was found that several navigations- and communication technologies are required for the resident drones. Some navigation technologies can be used to complement each other and act as a safety barrier if one method fails. The varying capabilities and constraints of the communication technologies presented means that all three methods presented are needed.
A solution for a subsea warehouse was presented. This concept was a retrievable unit that could be fitted on the suction anchor of a template. The warehouse had storage for a change out tooling system, a skid payload and room for spare parts. It was found that some parts of an all-electric control system and some electric actuators are feasible to store subsea.
A concept for a frame added to an ITS for supporting a subsea docking station was investigated. This concept was compared to having the dock located on one of the ITS suction anchors. Placing the dock on the suction anchor was decided to be the best solution of the two, as it blocked less access to the Xmas trees.
To compare the placement of an integrated- and standalone docking station, a case study was performed on the subsea facilities at the Troll field. It was found that the standalone solution gave the shortest average distance between a docking station and the subsea facilities.