The goal of the project was to design, build, and deploy a drilling device that will enable researchers to collect short cores of gas hydrate from deposits that occur at the sea floor.
Texas A&M University-Corpus Christi – project design, data collection and project management
Harbor Branch Oceanographic Inst. – drill design and fabrication
University of Nebraska – microdrill modification
College Station, TX 77843
Prior to this project, there was no device for collecting hydrate and sediment cores from the Johnson Sealink submersible. This project was funded to develop such a drill system. In addition, a field program of time-series photographic and temperature monitoring of the sampling sites was included in the project in order to quantify in situ physical and chemical properties of gas hydrate mounds.
During the first year of the project a hydrate microdrill was designed and fabricated in collaboration with Harbor Branch Oceanographic Institution. The drill has six detachable titanium coring bits that measure 11.5 inches (29 cm) in length and have an 0.875 inch (2.22 cm) internal diameter. The drill is placed in operating position by the mechanical arm of a submersible while separate hydraulic functions rotate and advance the coring bits. Constant pressure on the drill-face during the drilling process is maintained with a spring tensioner. After a core has been collected, the bit is detached into a collection chamber and a new bit is rotated into position. Recovery of the core samples is accomplished through the use of a pressure chamber.
An initial program of sample collection, observation, and instrument deployment was completed during a cruise aboard the RV Seward Johnson II and the submersible Johnson Sea Link in the Gulf of Mexico during July 3-18, 2001. During this program, the hydrate microdrill was tested at hydrate deposits located in the Bush Hill/Green Canyon Block 185 and Green Canyon Block 234 sites. Temperature measurements, time-lapse photographic monitoring, and documentation of gas hydrate in-situ characteristics were completed at these sites and at the Mud Volcano and Brine Pool sites.
During the cruise, researchers carried out a series of dives with the submersible, supplemented with sampling and observation from the surface ship. Activities included collection of methane hydrate, sediment, water, and other materials from methane hydrate and seep sites located at about 1800 ft (550 m) depths on the continental slope south of Louisiana. The researchers also deployed instruments to monitor and sample the physical and geochemical environment at the study sites. These instruments included a digital time-lapse camera and autonomous recording thermistors to measure the temperatures of bottom water, sediment (at 16 inches depth) and the interior of hydrate deposits (at 5 inches depth). In addition, a series of six RADARSAT synthetic aperture radar (SAR) images were collected over the study region. After completion of the cruise in 2001, the micro-drill system was modified to accommodate a larger core bit that could accommodate cores up to 10 inches (25 cm) long and 2.5 inches (6.4 cm) in diameter.
During the second year of the project, the major effort was to utilize the large bore drill in support of the Gas Hydrate Observation, Sampling and Tracer Study (GHOSTS) sponsored by DOE-NETL and the Life in Extreme Environments (LExEn) program sponsored by the National Science Foundation. The GHOST cruise was completed during June 6-14, 2002 while the LExEn cruise was completed during July 3-20, 2002. The modified drill system was successfully deployed and recovered large and small diameter pieces of hydrate.
The time-lapse camera system and recording thermistors deployed during the 2001 cruise were recovered during the GHOSTS cruise. The camera had successfully recorded 4 pictures per day over a 96-day time period. The thermistors successfully recorded bottom water, sediment and hydrate temperatures during the entire 327-day interval. Following the data recovery, the camera was redeployed to continue the time series. Additional samples were collected with the small diameter coring equipment, but problems with the systems drive shaft limited its effectiveness. Additional RADARSAT images were collected to assess the remote sensing signature of the gas hydrate sites A total of eleven images were used to identify ocean surface oil slicks that could be correlated to potential subsea seeps and associated hydrate mounds. After the 2002 fieldwork was completed, modifications to the hydrate drill were made to correct problems encountered during the cruise.
The fieldwork was successfully completed. The drill is fully operational. The hydrate drill and related instruments will continue to be deployed in support of other hydrate characterization efforts.
In addition to the information provided here, a full listing of project related publications and presentations as well as a listing of funded students can be found in the Methane Hydrate Program Bibliography [PDF].
Final Report [PDF-1242KB] - May, 2003
De Beukelaer S., I. MacDonald, N. Guinnasso, and J. Murray, 2003, Distinct side-scan sonar, RADARSAT SAR, and acoustic profiler signatures of gas and oil seeps on the Gulf of Mexico slope, Geo-Marine Letters 23(3-4), p. 177-186.
Liefer, I., and I. MacDonald, 2003, Dynamics of the gas flux from shallow gas hydrate deposits: interaction between oily hydrate bubbles and the oceanic environment, Earth and Planetary Science Letters 21(3-4), p. 411-424.
MacDonald, I., L. Bender, M. Vardaro, B. Bernard, and J. Brooks, 2005, Thermal and Visual Time-Series at a Seafloor Gas Hydrate Deposit on the Gulf of Mexico Slope, Earth and Planetary Science Letters, 233, p. 45-59.
MacDonald, I., G. Bohrmann, E. Escobar, F. Abegg, P. Blanchon, V. Blinova, W. Brückmann, M. Drews, A. Eisenhauer, X. Han, K. Heeschen, F. Meier, C. Mortera, T. Naehr, B. Orcutt, B. Bernard, J. Brooks, and M. De Faragó, 2004, Asphalt volcanism and chemosynthetic life, Campeche Knolls, Gulf of Mexico, Science, Vol. 304, No. 5673, pp. 999-1002.
MacDonald, I., I. Leifer, R. Sassen, P. Stine, R. Mitchell, and N. Guinasso, 2002, Transfer of hydrocarbons from natural seeps to the water column and atmosphere, Geofluids, Volume 5, p. 95-107.
MacDonald, I., W. Sager, and M. Peccini, 2003, Association of Gas Hydrate and Chemosynthetic Fauna in Mounded Bathymetry at Mid-Slope Hydrocarbon Seeps: Northern Gulf of Mexico, Marine Geology, Volume 198, p.133-158.
De Beaukelaer, S., 2003, Remote sensing analysis of natural oil and gas seeps on the continental slope of the northern Gulf of Mexico, 2003, Master’s Thesis, Department of Oceanography, Texas A&M University, August.
Vardaro, M., 2004, Deep-sea time-lapse camera observations: Temporal changes in gas hydrate mound topography and ecology, Master’s Thesis, Department of Oceanography, Texas A&M University, May.
MacDonald, I., M. Vardaro, and L. Bender, 2003, A Temperature and Photographic Time-Series from a Seafloor Gas Hydrate Deposit on the Gulf of Mexico Slope, Geophysical Research Abstracts, Volume 5, 12714.
MacDonald, I., M. Kastner, and I. Leifer, 2005, Estimates of natural hydrocarbon flux in the Gulf of Mexico basin from remote sensing data, European Union of Geosciences Meeting, Vienna, Austria, April 24-29.
MacDonald, I., P. Sobecky, J. Montoya, and S. Joye, 2003, Research issues in the Hydrocarbon Seep System in the northern Gulf of Mexico, American Society of Limnology and Oceanography Meeting, Salt Lake City, UT, February 10-14.
MacDonald, I., and I. Leifer, 2002, Constraining rates of carbon flux from natural seeps on northern Gulf of Mexico slope, Azerbaijan, NATO workshop on gas hydrates, October.
MacDonald, I., D. Power, I. Leifer, K. Lane, and J. Youden, 2002, The remote sensing signature of hydrocarbon seeps and implications for carbon flux, Honolulu, HI, American Geophysical Union Ocean Sciences Meeting, February 11-15.
MacDonald, I., P. Sobecky, J. Montoya, and S. Joye, 2001, Deposits of gas hydrate on the Gulf of Mexico slope: A natural laboratory for hydrate research, Brest, France, Second International Symposium for Deep-Sea Hydrothermal Vent Biology, October 8-12.