The goal of this project is to conduct activities leading to the development, implementation, and operation of a remote, multi-sensor seafloor observatory focused on behavior of the marine hydrocarbon system within the gas hydrate stability zone of the deepwater Gulf of Mexico and analysis of data resultant from that observatory over time. Attaining this goal will lead to an enhanced understanding of the role the hydrocarbon system plays in the environment surrounding the site. Investigations include physical, chemical, and microbiological studies. Models developed from these studies are designed to provide a better understanding of gas hydrates and associated free gas as (1) a geo-hazard to conventional deep oil and gas activities; (2) a source of hydrocarbon gases venting to the water column and, eventually, the atmosphere, with global climate implications; and (3) a future potential source of energy.
The Gulf of Mexico-Hydrate Research Consortium (GOM-HRC), formed to coordinate efforts of hydrates researchers and to promote effective, efficient communication among them, is in its eleventh year of developing a sea-floor station to monitor hydrates in situ. Consortium management includes facilitating research activities, sensor testing, and deployments; cooperation among participants; and reporting via planning regular consortium meetings and research cruises as well as interacting with sponsoring agencies. Established at and administered by the University of Mississippi’s Center for Marine Resources and Environmental Technology (CMRET), the consortium has, as its primary objective, the design and emplacement of a remote monitoring station on the sea floor in the northern Gulf of Mexico. The Monitoring Station/Sea-Floor Observatory (MS/SFO) is a multi-sensor station that will eventually provide more-or-less continuous monitoring of the near-seabed hydrocarbon system within the hydrate stability zone (HSZ) of the northern Gulf of Mexico.
The site of the observatory, Mississippi Canyon 118 (MC 118), is about 100 miles south of Pascagoula, MS, and was chosen by consensus of the consortium and its funding agencies based on favorable hydrate conditions at the site. The site is dominated by a fault-derived canyon in the northwest and a carbonate mound approximately 1km in diameter to the south. The mound is composed of three crater complexes, as seen in the multibeam image below.
The centerpiece of the SFO will be a series of vertical and horizontal arrays of sensors. One vertical geophysical component is complete and has been tested successfully. It is moored to the sea floor, extends 200 meters into the water column, includes hydrophones to record water-borne acoustic energy (and measure sound speed in the lower water column), thermistors to measure water temperature, tilt meters to sense currents, and compasses to indicate their directions. Another vertical array will consist of hydrophones and 3-component accelerometers to be installed in a borehole. Horizontal water-bottom hydrophone arrays will be laid on the soft sediments of the sea-floor by means of a sea-floor sled designed to lay cable. This sled will also be used as a seismic source of compressional and shear waves. Novel processing techniques for vertical and horizontal array data continue to be developed by consortium participants.
The SFO is expected to have a profound impact on our understanding of how natural gas hydrate deposits in the GOM undergo change over time and the repercussions of such changes. Quantification of the volume of natural gas released into the water column from hydrate deposits located on or near the sea-floor as seasonal current and temperature changes occur is one very important finding. Data gathered at the SFO will enhance ongoing efforts to model how hydrates form and dissociate, and will play an important role in the development of methodologies for carrying out commercial natural gas recovery and improving our ability to model climate change. In addition, these observed changes are expected to enhance our understanding of how hydrates affect seafloor stability, a factor critical for the placement and operation of subsea equipment, pipelines, and platforms.
Test of sea-floor probe for sensor deployment and core recovery as well as deployment of pore-fluid sampling and thermistor arrays at MC 118, were successful.
The Consortium identified the site for the Sea-Floor Observatory in Mississippi Canyon 118; designed and constructed the tools necessary to further understand methane hydrates deposits in the GOM (Raman spectrometer, prototype hydrophone vertical line array, and pressure pore-water sampler (PPPS)). The Project documented the first experimental knowledge of microbiological effects on the rate of hydrate formation under Gulf of Mexico sea floor conditions, and measured thermal properties of gas hydrate deposits over a one-year deployment with visual monitoring via time-lapse photography.
The project ended on July 31, 2013. The final report is available below under "Additional Information".
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 Project Report [PDF-24.6MB] December, 2013
Final Report for Project NT41268 [PDF-9.63MB]