Pioneering Robotic Autonomous Underwater Vehicle (AUV) with Electric Field Gradient Sensor – Transforming UnderWater Pipeline Inspections

Abstract Conventional underwater pipeline inspections typically utilize Remotely Operated Vehicles (ROVs) tethered to Dynamic Positioning Class 2 (DP2) vessels, which entail significant expenses. To reduce these expenses, alternative inspection approaches have been explored. The Robotic Autonomous Underwater Vehicle (AUV) offers a cost-effective alternative by eliminating the need for a DP2 vessel and can instead be deployed using a more economical DP1 vessel, pioneering the underwater pipeline inspection. This game-changing Robotic AUV with Electric Field Gradient Sensor (EFGS) integration using a DP1 vessel can reduce inspection costs by up to 55% compared to using a ROV with a DP2 vessel. Additionally, it can reduce inspection durations from 19 days to just 7 days (a 60% reduction), significantly lowering the cost and carbon footprint due to the shorter execution time. The development of the AUV technology integrated with EFGS was a collaborative effort between PETRONAS and AUV developer, ROVULA. This innovative technology has successfully completed its pilot deployment in November 2024, inspecting a 30″ pipeline over a total length of 155 km offshore Sarawak. The Robotic AUV can achieve superior inspection coverage compared to conventional ROV methods and accomplishes the task in less time. This advantage is due to the untethered operation of the lightweight AUV, which allows it to move twice as fast as the ROV and eliminates the need for physical contact with the pipeline. The EFGS technology performs non-contact cathodic protection (CP) measurements. Unlike the conventional ROV CP stab method, which requires the ROV to frequently stop and stab the CP probe onto the anodes and bare metal (if exposed), the AUV with EFGS moves along the pipeline without stoppage. It accurately measures the field gradient along the entire pipeline without contacting the anodes or pipeline, even if it is buried.