Subsea Infrastructure Inspection: A Review Study

Due to the increasing energy demands, the offshore energy business has boomed in recent decades. Sub-sea pipeline and power transmission cable installations are commonly applied worldwide. Any potential breakages can cause equipment damage and also damage the environment. The majority of the offshore pipeline inspections are currently committed using Towed or Remotely Operated Vehicle (ROV) systems. It is well-known that the ROVs are very time-consuming and expensive to operate, with respect to the fact that they require a relatively large support ship to accommodate the equipment as well as very skilled pilot and crews.
The paper examines the existing challenges related to the sub-sea inspection in general, the ROVs, AUVs and semi-autonomous ROVs advantages and disadvantages in different subsea inspec-tion applications.
Replacing the ROVs with Semi or fully-Autonomous Underwa-ter Vehicle (S-AUVs) can significantly change the inspections of infrastructure, as these vehicles could be much cheaper to deploy. S-AUVs can potentially conduct faster data collection and provide higher inspection data quality. However, there are still some technical challenges related to: underwater wireless communi-cation; battery and propulsion capacity; independent/supported navigation and localization; refueling and recharging, including underwater docking station feasibility; as well as the coordination and communication of a group of vehicles. In general, the offshore industry is conservative in the adoption of highly autonomous (not directly supervised) systems in general, and this seems to also be the case for S-AUV technology, in part due to regulatory requirements and certifications.
This study concludes that semi-autonomous upgrades to exist-ing ROV technology is a realistic first step towards the adaption of AUVs for the task of sub-sea infrastructure inspection. This opens the possibility to increase the capabilities of these existing solution the semi-autonomous way without a large increase in construction cost and without fully moving to an tether-less AUV solution.