Types of Methane Hydrate Deposits
Methane hydrate is a cage-like lattice of ice inside of which are trapped molecules of methane, the chief constituent of natural gas. If methane hydrate is either warmed or depressurized, it will revert back to water and natural gas. When brought to the earth's surface, one cubic meter of gas hydrate releases 164 cubic meters of natural gas. Hydrate deposits may be several hundred meters thick and generally occur in two types of settings: under Arctic permafrost, and beneath the ocean floor. Methane that forms hydrate can be both biogenic, created by biological activity in sediments, and thermogenic, created by geological processes deeper within the earth.
While global estimates vary considerably, the energy content of methane occurring in hydrate form is immense, possibly exceeding the combined energy content of all other known fossil fuels. However, future production volumes are speculative because methane production from hydrate has not been documented beyond small-scale field experiments.
The U.S. Department of Energy methane hydrate program aims to develop the tools and technologies to allow environmentally safe methane production from arctic and domestic offshore hydrates. The program includes R&D in:
- Production Feasibility: Methane hydrates occur in large quantities beneath the permafrost and offshore, on and below the seafloor. DOE R&D is focused on determining the potential and environmental implications of production of natural gas from hydrates.
- Research and Modeling: DOE is studying innovative ways to predict the location and concentration of subsurface methane hydrate before drilling. DOE is also conducting studies to understand the physical properties of gas hydrate-bearing strata and to model this understanding at reservoir scale to predict future behavior and production.
- Climate Change: DOE is studying the role of methane hydrate formation and dissociation in the global carbon cycle. Another aspect of this research is incorporating GH science into climate models to understand the relationship between global warming and methane hydrates.
- International Collaboration: International collaboration continues to be a vital part of the program since gas hydrates represent research challenges and resource potential that are important on a global scale.