Faster, more accurate and more cost-effective inspections. That is the promise of the next AUV autonomous underwater vehicle, which, in the future, will help to preserve and improve the integrity of subsea pipes in the deep offshore developments operated by Total.
From the Remotely Operated Vehicle (ROV) to the Autonomous Underwater Vehicle (AUV)
The integrity of subsea installations is one of the most strategic topics in deep-offshore production. A failure always hinders production. In the case of a hydrocarbon or chemical leak, it can also harm the environment. In all cases, the extensive logistical resources that are required to repair the fault are very costly. At the moment, we carry out inspection campaigns that are designed to anticipate and prevent failures with a Remotely Operated Vehicle (ROV) that is piloted on the sea’s surface from a dedicated boat. However, we face two problems: the growing cost and the shortage of these conventional inspection resources.
Optimizing these operations is vital, especially as we are getting ready to push future developments into ultra-deep offshore and very remote areas. To tackle this challenge, we have committed ourselves with Chevron in an intensive R&D program to develop a new generation of Autonomous Underwater Vehicle (AUV) inspection with increased autonomy. With no connection to the surface, this robot will have enough equipment to replace the inspection ROV.
Better performance at a lower cost
The main aim of this program is to develop an AUV that will acoustically (sonars) and visually (camera/laser) inspect the subsea pipelines and any deteriorations affecting the sea floor (sliding or shifting on which they lie). For Total, which currently operates 5,000 km of subsea pipeline, this technological leap will offer substantial advantages, both financial and technological:
- lower costs: as an AUV will be able to carry out an inspection four times faster than an ROV, the campaigns will not take as long and their daily cost will be lower as fewer logistical resources will be required
- greater control over HSE: smaller surface crews means fewer people exposed to lifting operation risks; meanwhile, hydrocarbon leak detection, a key function, will be entrusted to the AUV
- more effective inspections: thanks to a vehicle that has a more suitable shape for carrying all the required sensors at the same time than the ROV or ROTV
The pipeline inspection AUV: a host of on-board technology
Developed with Oceaneering from the specifications defined in partnership with Chevron, the pipeline inspection AUV can be launched to carry out a 24-hour dive from any vessel or base.
Travelling without any assistance from the surface, it will have to detect and avoid obstacles thanks to a sonar system that has a range of nearly 300 m. It will use innovative technology to automatically follow the pipelines, combined with an inertial navigation unit and a path correction system. The high level of accuracy achieved will enable the AUV to travel only 2.5 m above the pipeline, with a better resolution compared to traditional AUVs..
Its multi-beam echo sounder will provide 3D images of the pipeline and sea floor. An underwater laser scanner will detect any deformations, cracks or free spans affecting the pipelines. High-resolution digital photos, assembled using a mosaic-based technique, will provide a complete image of the pipeline. Another remarkable innovation: a contactless sensor that measures electric potential will be used to monitor the cathodic protection of the pipelines against corrosion.
Initial campaigns conducted at sea since 2015 on one of Chevron’s deep offshore fields (Gulf of Mexico, nearly 2.000m depth) have demonstrated the reliability of the navigation system, which is crucial for the quality of future inspections. A number of tests were successfully completed on the interfaces which will allow the AUV to communicate with the surface during operations. Among other things, complementary tests including a new monitoring system for cathodic protection were also carried out in 2017, confirming the importance of a perfect controllability of the AUV in deep offshore in order to maintain its race above pipelines at average speeds of 3 knots.
Additional qualification efforts are underway with our partners to plan a first pilot application in 2020. This will be the first stage of a more ambitious development plan for this autonomous underwater vehicle with increased autonomy (on-board decision-making capability). By 2022, the aim is to have a complete and reliable surveillance AUV, capable of inspecting all underwater equipment in great depths and to consider a resident application.
Check our deep offshore dossier on TOTAL.COM
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