| Location: | Discoverer Deep Seas, Walker Ridge 316 |
| Position: | Gulf of Mexico |
| Depth: | 6,168 ft (1880 m) |
| Water Temperature: | 4.4°C |
| Dates: | January 2009 |
| Industry Partners | |
| Gas & Oil Company | Chevron |
| ROV Operator: | Subsea7 |
| Rig operator: | Transocean |
| SERPENT Representatives: | Mark Benfield and Marianne Alford |
Mission Plan
This was the second Gulf SERPENT mission to the DDS following a trip during February 2007 when we begin our collaboration with Chevron. During that initial 2007 trip we received outstanding ROV support which produced excellent observational data; however, no subsequent observations were collected by the DDS. This was due to a combination of factors: the departure of Tony Kastropil (ROV Superintendent) who had been a keen supporter of SERPENT; heavy tasking of the ROV in support of drilling, and the vessel going off-contract from Chevron for an extended period.
We are committed to rebuilding and expanding our partnership with Chevron and the DDS in order to collect regular SERPENT data over the next year and beyond. Consequently, a site visit to familiarize everyone with our protocols and program is the logical first step. This was also an opportunity to begin training our technician (Ms. Marianne Alford) in offshore procedures so that she can undertake future missions to the DDS and other partner sites. During this mission we planned to conduct a current velocity/direction survey. The depths for the current measurements would be: 6053; 5000; 4000; 3000; 2000; 1500; 1000; 500; 300; 100; and 50 feet. We also planned to collect data from a series of video transects in the water column. The initial dive would begin at 500', descending at 500’ intervals to the bottom. Horizontal transects will be conducted out to 300 ft from the TMS.
Results
Tuesday 27 January 2009
We began the current velocity/direction survey at 11:44 and completed transects at 6000, 5000, 4000, 3000, and 2000 ft. After the 2000 ft survey, we decided to suspend further SERPENT surveys for the day in order to ensure the ROV had time to complete the current survey.
Wednesday 28 January 2009
Spent the morning
working down to 3500 ft and continued down through the afternoon. One interesting discovery
was the use of the 670 kHz sector scan to locate targets. By setting the gain to 100% we could
detect scattering from siphonophores and fish. Our observations of a pair of unusual midwater
fishes that were vertically-oriented at 3500 ft was due to their detection on the echosounder.
The Sontek ADP also provided a real-time record of the water temperature although we did not
configure it to log data.
We completed all ~300 ft horizontal transects at 500 ft vertical intervals from 500 ft - 6000 ft. Three DVDs were collected. It’s important to note that we only recorded during the horizontal transcripts and stopped recording during descents and the final ascent to the surface.
