AUTONOMOUS VEHICLES & SUBSEA ANALYTICS Improve the accuracy of underwater cathodic protection surveys Autonomous vehicles and improved analytics offer effective methods for pipeline inspection By Adam Haavisto T o reduce risk and increase inspec-tion speeds—while lowering costs—for underwater pipeline surveys, new inspection methods must be considered. Current meth-ods are slow, capital intensive, and tend to produce a low value-to-cost ratio. In fact, pipeline surveys rarely identify issues, but are nevertheless required, either through regulations or company guidelines. Therefore, they are a sunk cost that needs to be reduced, and autonomous underwater vehicles (AUVs) may provide the means. Oceaneering is developing a method for inspecting subsea pipelines that uses AUVs combined with analytical techniques and machine learning. The aim is to improve data quality and reduce costs compared to the current practice of using a remotely operated vehicle (ROV) to perform pipeline and cathodic-protection (CP) surveys. The overall goal is to reduce offshore time, which is the largest cost factor, while still maintaining the data quality of ROV surveys. Yesterday and today Traditionally, long pipelines are inspected with an ROV. The ROV is operated by a pilot on the service vessel, an expensive proposition in and of itself. The benefits of this method are instant feedback, the ability to reroute (or sidestep) for spans, inspection flexibility, and direct CP measurements. The challenges associated with this method are pace, weather, and poor track records for performing CP surveys, as well as ill-equipped ROVs. In this scenario, the ROV sits on top of the pipeline in order to walk it, taking remote electrode measurements and pipeline footage and data. Besides extended use of the service vessel, the ROV relies on cameras to perform visual inspections, along with direct stabs that make physi-cal contact with the pipeline The C-Surveyor AUV fleet can provide high-resolution pipeline inspection services, equipped with a Kongsberg Simrad EM2040 Multibeam Echo-sounder, high-resolution digital cam-era, 2G Robotics high-resolution laser bathymetry system, magnetometer, and a GeoChemical suite of sensors. The geo-referenced still photo imagery, laser data, and multibeam data allow for change detection across surveys. All photos courtesy: Oceaneering 14 • APRIL 2018 OIL & GAS ENGINEERING
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