AUV technology for seabed characterization and geohazards assessment

Autonomous underwater vehicles (AUV) are untethered submarine robots that can be used to carry out deepwater mapping and seabed-characterization surveys (seafloor to 150-m depth). AUV surveys are used in the marine petroleum industry for various exploration, environmental, geohazard, and engineering applications. Typically, AUVs are launched from a mother ship. They execute a preprogrammed survey pattern and are recovered, and the survey data are downloaded for analysis. Data on water depth, geomorphology, stratigraphy, and structure ranging downward to 150 m below the seafloor routinely are collected using a variety of sensing technology. Principal survey tools include a multibeam echo sounder to provide water column, bathymetric, and seafloor-reflectivity data; a side-scan sonar to provide high-resolution seafloor imagery; and a subbottom profiler (1- to 24-kHz seismic-reflection tool) to show subseafloor stratigraphy and structural features. Other AUV survey tools can include still cameras, lidar scanners, magnetometers, geochemical sensors (CO2, CH4, PAH, dissolved oxygen), and temperature and salinity sensors. AUV surveys help deepwater exploration and development to proceed efficiently and safely and thus have become an indispensable tool for deepwater operations.