Feature ArticleFrom Survey Class To Inspection Class
By Jami J. Cheramie • Peter J. Alleman
From its inception in 1992, C&C Technologies (Lafayette, Louisiana) has brought new technologies to the oil and gas industry. In the late 1990s, with oil and gas exploration going deeper and deeper, it became evident that a replacement for deep tow systems was approaching. Deep tow technology was expensive and its shortcomings of poor depth-related navigation, extreme tow lengths and turn times created a crossover point that would allow AUV technology to provide a viable economic solution.
In late 1998, C&C began a research and development (R&D) project to determine if AUV technology could be improved to meet the geophysical survey needs of the commercial oil and gas industry. Reviewing the history of deep tow technologies and their shortcomings, as well as the needs of industry, showed that certain criteria were critical for AUVs to replace a deep tow system economically. First and foremost, the size of the AUV must allow for the simultaneous collection of multibeam, sub-bottom and side scan data. Collection of all data sets during one mission was considered a key element in analyzing the cost benefits of an AUV over a deep tow. Second, it had to support a run time of 48 hours with all systems running. And, third, it had to be able to integrate an ultrashort baseline (USBL)-aided inertial navigation system (INS) that could support the accuracies for geophysical surveys.
After a long process of determining possible candidates to team with C&C in the design and building of the AUV, Kongsberg Maritime (Kongsberg, Norway) was chosen to build a 3,000-meter-rated AUV based on its work on the HUGIN military version. Kongsberg had experience in designing an AUV ďtruckĒ body capable of supporting all sensors considered critical. And, with its close relationship with FFI, the Norwegian naval research lab, Kongsberg was able to provide an energy source and navigation system to support C&Cís AUV design goals. C&Cís R&D team—through its work with multibeam, side scan and sub-bottom surveys, and its experience integrating sensors into the U.S. Naval Research Labís Orca project—would provide the payload system and sensor integration side of the equation.
Thus after a nearly two-year process of research, design, build and testing, C&C started commercial service of the C-Surveyor I AUV in the Gulf of Mexico in January 2001. The specs for the first in its line of survey-class AUVs include a 3,000-meter-rated body and sensors, Kongsberg EM 2000 200-kilohertz multibeam echosounder, 120/410-kilohertz EdgeTech (West Wareham, Massachusetts) side scan sonar, 2-to-16-kilohertz EdgeTech chirp sub-bottom profiler, 48-hour run time semifuel cell energy source and a USBL-aided INS capable of 3-to-6-meter accuracy in 3,000-meter depths.
Since that successful launch in 2001 and through the end of 2012, C&Cís line of C-Surveyor AUVs has surveyed more than 300,000 kilometers for more than 66 unique clients in 14 countries, encompassing 376 deepwater projects. Most of the work to date has been in support of standard geophysical surveys for hazard investigations, archeological surveys for the Bureau of Ocean Energy Management, pipeline route survey and wide-area block surveys. Over the years, there have been improvements to the systems and sensors to better support geophysical surveys—an improved sub-bottom and side scan system in 2005, improvements to depth rating to support 4,500 meters and, in 2010, additional sensors, including a geochemical sensor suite of CH4 (methane), CO2 and PAH (polycyclic aromatic hydrocarbon).
Beginning in 2009, C&C began R&D on expanded uses of AUV technologies to see if their unique capabilities could affect other aspects of oil and gas surveys. An immediate area of interest was identified in the pipeline inspection work being carried out by ROVs. Just as AUVs had revolutionized deepwater surveys, C&C believed that their intrinsic efficiencies could be expanded to support pipeline work. Various domains were identified to be addressed in designing and choosing sensors for supporting the inspection of pipelines.
Towards an Inspection-Class AUV
C&C considers its C-Surveyor line to be survey grade—its primary sensors are suited for standard geophysical survey data. The multibeam, side scan and sub-bottom provide the data sets and quality needed by installation engineers in choosing, designing and installing subsea infrastructure. They do not fully support data sets necessary to support pipeline analysis.
To progress towards an inspection-class AUV, three areas of sensor improvement or additions were identified: A camera for photo analysis of pipe casing events and corrosion detection, a geochemical suite for leak detection and an improved bathymetry system for pipe spanning and straightness measurements. To continue this article please click here.
Pete J. Alleman has a bachelor of science degree in physics and has been chief scientist at C&C Technologies for 21 years. Allemanís expertise includes design and development of sonar systems, imaging systems, and automation of control systems and data acquisition systems.
Jami J. Cheramie is vice president of systems development, IT support and special projects at C&C Technologies. He has been working with AUV technology since 1998 when C&C started its commercial line development program. His work has included the addition of new sensors and the development of techniques to extend the use of AUVs as the default tool for deepwater geophysical/geohazard surveys.