EMD: Hydrates, Coal Gas Hold Promise

Fire and Ice for the Future -- Hydrates, Coal Gas Hold Promise

Locked under ice and permafrost in Alaska and in remote reaches of the Arctic lie vast resources to fuel our nation's energy future. The tremendous volume of methane gas hydrates in the permafrost regions of the world make tapping into this unconventional resource a critical component to add to our nation's energy portfolio.

The antithetical extremes of this resource — the potential of fire captured in ice crystals — make it a compelling challenge to turn the unconventional into the conventional. While gas hydrates hold great potential as an "environmentally friendly" fuel for the 21st century, considerable technological challenges currently hinder using them as a resource. Their occurrence in icy and remote areas without an infrastructure for delivery presents a daunting challenge.

There are scientific challenges as well — we need to more fully understand the geologic parameters controlling the occurrence and distribution of gas hydrates in order to put a more accurate number on the amount of methane sequestered as gas hydrates worldwide.

Resource estimates are currently speculative and range over several orders of magnitude, from about 100,000 to 270,000 trillion cubic feet, according to broad extrapolations done by U.S. Geological Survey scientists in the 1990s (Figure 1).


One of the most exciting aspects of the gas hydrate quest is the tremendous opportunity for collaboration and innovative partnerships between industry, government and academia.

The USGS has been a partner in the consortium for the Mallik Project in the Mackenzie Delta of the Canadian Arctic, which involves Canada, Japan, Germany, India and the United States, and more than 100 scientists and engineers.

At the Mallik site, scientists and engineers conducted the first fully integrated field study and production testing of a natural gas hydrate accumulation, which is showing that this resource holds considerable potential as a fuel source.

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Locked under ice and permafrost in Alaska and in remote reaches of the Arctic lie vast resources to fuel our nation's energy future. The tremendous volume of methane gas hydrates in the permafrost regions of the world make tapping into this unconventional resource a critical component to add to our nation's energy portfolio.

The antithetical extremes of this resource — the potential of fire captured in ice crystals — make it a compelling challenge to turn the unconventional into the conventional. While gas hydrates hold great potential as an "environmentally friendly" fuel for the 21st century, considerable technological challenges currently hinder using them as a resource. Their occurrence in icy and remote areas without an infrastructure for delivery presents a daunting challenge.

There are scientific challenges as well — we need to more fully understand the geologic parameters controlling the occurrence and distribution of gas hydrates in order to put a more accurate number on the amount of methane sequestered as gas hydrates worldwide.

Resource estimates are currently speculative and range over several orders of magnitude, from about 100,000 to 270,000 trillion cubic feet, according to broad extrapolations done by U.S. Geological Survey scientists in the 1990s (Figure 1).


One of the most exciting aspects of the gas hydrate quest is the tremendous opportunity for collaboration and innovative partnerships between industry, government and academia.

The USGS has been a partner in the consortium for the Mallik Project in the Mackenzie Delta of the Canadian Arctic, which involves Canada, Japan, Germany, India and the United States, and more than 100 scientists and engineers.

At the Mallik site, scientists and engineers conducted the first fully integrated field study and production testing of a natural gas hydrate accumulation, which is showing that this resource holds considerable potential as a fuel source.

The Mallik site was chosen because it represents one of the world's highest concentrations of gas hydrates.

Before Mallik, little was known about the technology necessary to produce gas hydrates, and these first successful results — shared at an international symposium in Japan last December — form the world's most detailed scientific information about the occurrence and production characteristics of gas hydrates.

(Detailed scientific and technical results are being published in a joint volume of the partners and will be released this fall as a Geological Survey of Canada publication.)

What we have learned from Mallik depressurization and thermal heating experiments is that gas can be produced from gas hydrates with different concentrations and characteristics, exclusively through pressure stimulation.

The data support the interpretation that the gas hydrates are much more permeable and conducive to flow from pressure stimulation than previously thought.

In one test, the gas production rates were substantially enhanced by artificially fracturing the reservoir. Hydrates also were produced using thermal heating in varying amounts.


Coalbed methane represents another unconventional resource with great potential. The large and complex internal surface area of coal enables it to store surprisingly large volumes of methane-rich gas — six or seven times as much gas as a conventional natural gas reservoir of equal rock volume.

That large potential is sparking tremendous interest in this unconventional resource, especially in Alaska, where the USGS recently assessed coal resources.

Whereas previous coal resource assessments attempted to assess the total coal in the ground — producing estimates that tended to be high — and to include coal deposits that contain beds that are too thin and/or too deep to be economically mined, this focused on beds currently being developed in existing mines, or in areas that are currently leased.

The assessment shows Alaska surpassing the total coal resources of the conterminous United States by almost 40 percent — an estimate of more than 5,500 billion short tons, which translates to an exceedingly large potential for coalbed methane, as much as 1,000 trillion cubic feet of in-place CBM resource (figure 2).

Most of those resources are found in the northern Alaska-North Slope and southern Alaska-Cook Inlet coal provinces where in-place and planned infrastructure (pipelines, highways, etc.) may potentially assist in mitigating the delivery challenges in the transportation and marketability of coalbed gas.

This could be a considerable boon to the native Alaskan people in remote areas. The USGS is working with native Alaskan groups, the state of Alaska and Interior's Bureau of Land Management to identify potential coalbed gas resources and to characterize the potential of this resource for their energy needs.

Proximity to pipelines would mean that Alaska coalbed gas could play a role in world supply. The short distance of coal and coalbed methane resources to countries in the western Pacific Rim makes them potentially more marketable to that sector of the world than to the rest of the United States.


What about conventional resources in Alaska?

The USGS 2002 re-assessment of the National Petroleum Reserve there showed that the federal part of NPRA contains significant volumes of technically recoverable oil and gas resources spread over a vast area. The same conundrum exists, however, for conventional as for unconventional resources — they're there but how do we get them where we need them?

The economic viability of the natural gas resources depends on the availability of transportation to the lower 48 and no natural gas pipeline currently exists.

The USGS and its Energy Resources Program are committed to delivering the energy resource information needed by land and resource managers, energy policy makers, other scientists, academia, private industry and the public at large — to provide science for decisions, and science for communities.


As USGS focuses this year on our 125th anniversary, we reflect back on how energy resource information has long been an essential part of our mission to "classify and examine" the national domain.

In his luncheon address to the EMD at last month's AAPG annual meeting, USGS associate director for geology Pat Leahy stressed the need for scientific research and new technology innovation as the nation's resource base becomes, of necessity, more dependent on unconventional resources. And nowhere is the "fire and ice" of that unconventional potential of higher profile and greater promise than in Alaska.

Working with national and international partners in industry, government and the academic community, the USGS is dedicated to providing the science that will ensure that we have the energy resources to fuel our economies and foster a clean and safe environment for future generations.

(Editor's note: Additional USGS energy information is at http://energy.usgs.gov.)