Greater concern about the safety of deploying personnel into an underwater environment is one of the drivers for pursuing new ways to survey subsurface assets. In response, AUVs are seeing broader use in the oil and gas industry.
Because AUVs have no umbilical and can operate at a distance from a host support vessel, they offer a number of advantages over the industry-dominant ROVs. Unlike tethered ROVs, AUVs can work in obstructed areas, maneuvering themselves to a work site using a self-contained power system and finding their way in a particular direction at a specified depth and speed using internal and external positioning sources. AUVs typically are more compact than ROVs and can work much more closely to the assets and with the potential of producing more accurate data.
AUVs can deliver cost-effective inspections in deep water and are being used to survey and inspect pipelines and flowlines and to verify the integrity of subsea structures. AUVs also are being used in geohazard surveys to obtain information on soil conditions and to identify potentially hazardous subsurface features. And more frequently, AUVs are being used for as-built surveys to verify newbuild pipeline conditions.
While AUVs deliver a broad range of capabilities, perhaps the biggest advantage is that using AUVs improves worker safety, reducing threats to personnel by removing them from hazardous work areas.
Unlike forecasts for many sectors in the offshore industry, the outlook for the AUV market is positive. Douglas Westwood’s most recent edition of the “World AUV Market Forecast” suggests that prospective demand for AUVs in a range of sectors will grow over the next five years. While governments are expected to be the biggest users—with demand in 2020 for more than 700 units—and research is ranked second, there also is forecast demand growth for offshore oil and gas applications. Altogether, AUV demand is expected to grow nearly 50% over the next four years. Interestingly, the report identifies growth potential in the renewables sector in addition to oil and gas applications, noting that these areas will have the greatest growth in usage.
Tracing the history of AUVs from emerging technology to niche applications to becoming an established component of offshore and marine operations, the report suggests that improvements in capabilities will expand AUV usage to new applications.
Inarguably, there is a lot to commend the use of AUVs, but there are multiple areas for improvement.
Inarguably, there is a lot to commend the use of AUVs, but there are multiple areas for improvement. For one, these units are battery-operated, and this limits the length of time they can be deployed. So battery research will be important in future AUV development. Maneuverability and retrieval could be simplified, and there is scope for more research aimed at improving AUV positioning and advancing sensor quality to improve the data being captured by AUVs.
Research and realities
Under a master research agreement that includes several universities, including the University of Michigan in Ann Arbor, Mich., and Carnegie Mellon University in Pittsburgh, Pa., ABS is contributing to AUV advancement.
Research is underway that focuses on using hovering AUVs (HAUVs) and navigation systems to address a number of limitations experienced with current models of AUVs. One interesting area of research is exploring the possibility of using AUVs for in situ inspection of commercial structures like hulls and spar tanks. Through this research program a trial was carried out on a commercial vessel to demonstrate the ability of an HAUV to automatically conduct hull inspection using a stereo camera for noncomplex areas. Tests were undertaken with the HAUV outfitted with this new type of camera, and the first steps have been made to develop software to improve the ability to visualize large inspection datasets collected by the HAUV to provide the human operator with a spatial context and intuitive interface.
Another initiative is investigating the possibility of identifying exterior hull surface conditions that can be cross-registered to 3-D computer-aided design models that will augment spatial database models of assets, allowing better monitoring of structural integrity and facilitating hull stress and fatigue analysis. This project is supplemented by a program that is evaluating how improved image resolution from AUVs can be used to improve the 3-D image of the hull.
A third research project is looking into how data collected from AUVs might be used for damage assessment in support of the Rapid Response Damage Assessment (RRDA) program, which provides an organized team of engineers, naval architects, master mariners and support staff that can respond 24 hours a day during emergencies. Enrollment in the ABS RRDA program provides asset owners with essential technical support when a vessel is involved in an incident.
While there has been marked progress in AUV research, much remains to be done. Future work will include efforts to explore methods of deploying AUVs in a broader range of applications, including the evaluation of offshore and marine assets for quality and safety certification. Advances in logistical deployment aim to simplify launch and recovery, and efficiencies will be pursued to make AUV use more attractive to the offshore market.
There is always room for improvement, and there are additional objectives beyond those achieved to date in this AUV research program. The goal is to work to improve the application of this technology to the point that it is mature enough to enable some of these initial achievements to be advanced. For example, AUV inspections of noncomplex hull areas could be improved to the level that they are applicable for complex inspections. The acquisition process, which stands today at several days for a simple hull inspection, could be shortened considerably to provide efficiencies. And while the data collected to date have proven to be valuable, it is evident that more value could be extracted if the data quality was improved.
From the perspective of a classification society AUVs provide a means to improve surveys and inspections in a way that takes people out of potentially hazardous or dangerous environments. This is one of the goals of the ABS FutureClass initiative, which focuses on leveraging data to facilitate class services and to provide surveyors with advanced inspection tools that provide greater insight into asset integrity while improving the safety of personnel. The goal of FutureClass is to make classification activities less intrusive and to allow asset owners to achieve more productive time by approaching classification as a riskbased, condition-based continuous effort. This method of working has the potential to refine and reshape the role of classification through a proactive, pragmatic approach to resolving challenges, creating safety guidelines and advancing innovative solutions for safer and more efficient operations. By applying this methodology, it is possible to incorporate new technologies and capabilities to change the traditional definition and scope of classification services.