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Abstract This paper describes a methodology for integrating Autonomous Underwater Vehicle (AUV) geophysical data with Remotely Operated Vehicle (ROV) video in order to predict environmentally sensitive deep-water chemosynthetic habitat. The methodology was developed using AUV geophysical data and ROV video acquired in BP's Puma appraisal area, in the U.S. Gulf of Mexico. The results from the AUV survey indicated dozens of hydrocarbon seepage sites with the potential to support high-density chemosynthetic communities. These communities are protected by U.S. environmental regulations and, thus, could significantly impact field development plans. The ROV video revealed a few high-density chemosynthetic communities and cleared certain critical areas for potential development, but it still left numerous possible hydrocarbon seepage sites un-cleared. It would have been a costly undertaking to inspect each site by ROV when they are so numerous and widely separated. Therefore, an alternative means of clearing as many of these sites as possible was needed. Upon integration of the ROV video with the AUV data, the following important observations were made:Densely populated chemosynthetic communities in the Puma area only occur at hydrocarbon seepage sites with relatively large (several 10's of cm or larger) carbonate outcrops;there is a strong correlation between this carbonate substrate and high-intensity backscatter in AUV multibeam sonar data; and, carbonate outcrops are distinctly visible in the AUV sidescan sonar data as anomalous seafloor mounds. These observations suggested that ROV observations could be used to calibrate the AUV geophysical data. The calibrated AUV data could then be used to predict what other sites away from the ROV survey track (without direct visual inspection) have the most potential for supporting high-density chemosynthetic communities. Based on the calibration results, inferred hydrocarbon seepage sites that exceed a specific seafloor backscatter intensity level, and contain anomalous seafloor mounds interpreted as authigenic carbonate, are the areas with the most potential for supporting high-density chemosynthetic communities at Puma. Other inferred hydrocarbon seepage sites that do not meet these criteria have a low potential for supporting high-density chemosynthetic communities, and are less likely to be subject to environmental regulations. The methodology utilized here helped prioritize areas of environmental concern at Puma, incase additonal ROV investigation is required. Additionaly, this method may be applicable in other settings where suitable AUV data and sufficient " ground-truth?? from ROV video exist. |
