EK60 Water Column Sonar Data Collected During PC1007

Deepwater Horizon SEAMAP data. Unconventional configurations for both the EK60s and the ME70 allowed for three-dimensional images to be created from the split-aperture acoustic data. The ME70 configuration developed required Simrad to provide new software.

Using the EK60's, we imaged methane seeps in many locations surrounding the wellhead and at the wellhead. Seeps occur naturally in this area, and the challenge is to identify new or more intense seeps. Using both the EK60s and the ME70, we imaged the Deepwater Horizon rig on the seabed, among many riser pipes and other apparatus. When the Subsurface Monitoring Unit expressed concern that the noise level was too high for observations near the wellhead, I identified that the signal could be increased and the noise decreased, improving the signal-to-noise ratio by an order of magnitude, by increasing the pulse durations at 18 and 38 kHz from one to four milliseconds. Enabled by this enhanced configuration, I identified that the wellhead was burping methane hydrate intermittently and the emissions were rising at approximately 10 m per minute. The source of the bubbles and hydrate were observed on the BP-ROV images taken at the wellhead. When BP complained that the horizontal res
olution of our detections was too poor due to the 11 degree beamwidth of the 18 kHz transducer, I advocated the use of our new biplanar interferometric technique which increased the resolution one to two orders of magnitude (from ca. 300 m to ca. 10-20 m at 1500 m range) and provided sub-beam imagery (detailed in Cutter and Demer, 2010). Randy implemented his biplanar interferometric software (now BP-interferometry) and is generating very high-resolution 3-D images of the wellhead, seeps, and surrounding area. I generated 3-D maps of the seep locations and acoustically-tracked four large targets in the area, perhaps sperm whales.