EarthWord–Gas Hydrate

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No, this EarthWord isn’t how natural gas quenches its thirst-it just sounds like it...

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image shows gas hydrate samples in blue-gloved hands
During Ocean Drilling Program Leg 204, nine sites were cored and wireline logged on the Oregon continental margin to determine the distribution and concentration of gas hydrates in an accretionary ridge setting, investigate the mechanisms that transport methane and other gases into the gas hydrate stability zone, and obtain constraints on physical properties of gas hydrates in situ. This image shows gas hydrates (the white material) in marine sediments.
(Courtesy of Ocean Drilling Program)

The EarthWord: Gas Hydrate

Definition:

  • Here’s a riddle: when can ice burn? When it’s a gas hydrate! Gas hydrate is a naturally-occurring, ice-like form of methane and water that is stable within a narrow range of pressure and temperature conditions.  These conditions are mostly found in undersea sediments at water depths greater than 1000 to 1650 ft and in and beneath permafrost (permanently frozen ground) at high latitudes.

Etymology:

  • Gas comes from the Greek word khaos, meaning “empty space.” It was first coined by Flemish chemist J.B. van Helmont to refer to vapors. Hydrate, meanwhile, comes from the Greek hydor, meaning “water.” It was first used by French chemist Joseph-Louis Proust to refer to a combination of water and another chemical.

Image shows gas hydrates in marine sediments with a ruler alongside to show scale
This image shows gas hydrates (the white material) in marine sediments from a test well drilled in the Indian Ocean in 2006 during the Indian National Gas Hydrate Program (NGHP) Expedition 01.
The NGHP Expedition 01 was designed to study the gas-hydrate occurrences off the Indian Peninsula and along the Andaman convergent margin with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. During NGHP Expedition 01, dedicated gas-hydrate coring, drilling, and downhole logging operations were conducted from 28 April 2006 to 19 August 2006. The NGHP Expedition 01 was planned and managed through a collaboration between the Directorate General of Hydrocarbons under the Ministry of Petroleum and Natural Gas (India), the U.S. Geological Survey, and the Consortium for Scientific Methane Hydrate Investigations led by Overseas Drilling Limited and FUGRO McClelland Marine Geosciences. Read more about the expedition here.
(Credit: Tim Collett, USGS. Public domain.)

Use/Significance in the Earth Science Community:

  • Gas hydrate, especially the version that contains methane, is of great interest to both climate and energy science.

  • On a global scale, gas hydrate deposits store enormous amounts of methane at relatively shallow depths, making them particularly susceptible to the changes in temperature that accompany climate change.  Methane itself is also a potent greenhouse gas, and some researchers have suggested that methane released by the breakdown of gas hydrate during past climate events may have exacerbated global warming.

  • In addition, the amount of methane, the main ingredient of natural gas, within the world’s gas hydrate accumulations is estimated to greatly exceed the volume of all known conventional natural gas resources.

Image shows a drill rig on a snowy landscape with the sun on the horizon
A drill rig at the Mallik test site in Canada's Mckenzie Delta.  USGS joined the Geological Survey of Canada, JAPEX, and the Japanese National Oil Company to drill test wells for natural gas production from gas hydrate deposits. Read more about the Mallik project here.
(Credit: Tim Collett, USGS. Public domain.)

USGS Use:

  • The USGS Gas Hydrates Project focuses on gas hydrates in the natural environment and seeks to advance understanding of the potential of gas hydrates as an energy resource; the role of gas hydrates in climate change, as well as their susceptibility to climate change; and gas hydrates and the stability of submarine slopes.

  • The Hydrate Pressure Core Analysis Laboratory (HyPrCAL) is the newest USGS Gas Hydrates Project facility and supports some of the Project’s energy research at the Woods Hole Coastal and Marine Science Center.  HyPrCAL was the first facility in the U.S. solely designed for and dedicated to the analysis of pressure cores.

  • In 2017, USGS and the University of Rochester released an interpretive review of all published literature regarding the interactions of climate and methane hydrates, and concluded that the risk of massive methane releases to the atmosphere due to gas hydrate breakdown was small.

  • In 2016, USGS participated in an announcement of a potentially producible deposit of gas hydrate in the Indian Ocean’s Bay of Bengal.

Image shows burning gas hydrates
Natural gas from gas hydrates burning. Methane, the primary component of natural gas, is the most common of the gases that form gas hydrate. In fact, the amount of natural gas within the world’s gas hydrate accumulations is estimated to greatly exceed the volume of all known conventional gas resources. Because of that potential, the USGS and academic, government, and private industry scientists and engineers have been studying how to produce natural gas from hydrates for many decades. Read more about our gas hydrate research here. Image courtesy of the Department of Energy.
(Public domain.)

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