USGS Gas Hydrate Assessment Shows Huge Energy Resource
23 September 2019
The Alaska North Slope contains an estimated 53.8 trillion cubic feet of natural gas hydrate resources, according to a new assessment by the U.S. Geological Survey. This estimate is for the undiscovered, technically recoverable natural gas resources stored within gas hydrate formations.
“The USGS is committed to providing the most up-to-date, publicly available, peer-reviewed estimates of the nation’s energy resources,” said Walter Guidroz, program coordinator for the USGS Energy Resources Program. “As more information becomes available, we sometimes need to revise our assessments to ensure they reflect the best available science.”
The every-10-years assessment updates a 2008 USGS assessment that estimated about 85 tcf of undiscovered, technically recoverable gas resources within North Slope. That assessment was the first-ever estimate of technically recoverable gas resources within gas hydrate.
Gas hydrates are naturally occurring, ice-like solids in which water molecules trap gas molecules in a cage-like structure. They are only stable within a narrow range of temperatures and pressures and are usually found in seafloor sediments and in Arctic onshore permafrost environments.
Although many gases form hydrates in nature, methane hydrate is by far the most common, and there are thought to be significant natural gas resources contained in the world’s gas hydrate accumulations.
“The study of gas hydrate as an energy resource is still an emerging field,” said USGS scientist Tim Collett, lead author of the assessment. “The USGS has been conducting research on gas hydrates since the 1980s. Every time we conduct these assessments, we incorporate more and higher quality data, and our estimates become more precise.”
The USGS has studied the resource potential of gas hydrates for more than 35 years. Partnering with agencies like the Department of Energy, the Bureau of Land Management, the Bureau of Ocean Energy Management and Alaska state agencies, as well as international, industry and academic partners, the USGS has analyzed gas hydrate formations throughout the United States and around the world.
The newly released 2018 gas hydrates assessment utilized more extensive 3D seismic mapping, improved data collection and more refined analysis. Access to better maps, as well as greater understanding of gas hydrate reservoir properties, allowed for more precise estimates. It is this refined analysis that yielded a smaller gas volume estimate in the 2018 assessment when compared to the 2008 assessment.
This assessment approach also assumes that the resource can be produced by existing conventional technology. To date, there is no known commercial production of natural gas from gas hydrate formation and the commercial viability of gas hydrate reservoirs is not yet known. This assumption is based on both limited field testing and numerical production models of gas hydrate-bearing reservoirs. No analysis was provided as to whether it would be profitable to produce these resources.
For more information on the USGS assessment, click here.