RS20050: Methane Hydrates: Energy Prospect or
James E. Mielke
Specialist in Marine and Earth Sciences
Resources, Science, and Industry Division
Updated February 14, 2000
Methane hydrate is a methane-bearing, ice-like material that occurs
in marine sediments and in permafrost regions. The amount of methane contained in hydrate
deposits is enormous, although it is likely that much of the hydrate occurs in low
concentrations and would have no commercial potential. Hydrate deposits are estimated to
contain a much greater amount of natural gas than conventional accumulations, however,
there is today no practical and environmentally safe way to produce the gas.
Destabilization of the hydrates with uncontrolled release of large volumes of methane is a
significant hazard. Legislation was introduced into the 105th Congress, which
would have authorized an interagency research and development program to develop methane
hydrate resources. The bill passed the Senate and hearings were held in the House before
Congress adjourned. The measure was reintroduced in the 106th Congress as S. 330, which was reported
from the Committee on Energy and Natural Resources on March 22, 1999 (S.Rept. 106-33).
The Senate passed S. 330
on April 19, 1999. Subsequently, H.R. 1753 was introduced
into the House and jointly referred to the Committees on Science and Resources. The bill
was reported from both Committees (H.Rept. 106-377,
Parts I and II) and passed the House on October 26, 1999. H.R. 1753 passed the
Senate as amended on November 19, 1999.
Background and Analysis
Methane hydrate is a mixture of methane and water that is frozen
into an ice. The crystalline structure of the frozen water molecules forms a cage-like
lattice inside of which are trapped high concentrations of methane molecules. Methane
hydrates form in generally two types of geologic environments, in permafrost regions
(where cold temperatures dominate) and beneath the sea in sediments of the outer
continental margins (where high pressures dominate). Methane hydrates can form at
temperatures above the freezing point of water. While methane (the chief constituent of
natural gas), propane, and other gases are included in the hydrate structure, methane
hydrates are the most common.
In the Arctic where the near-surface temperature is low, methane
hydrates form in the permafrost and can form a seal for gas seeping toward the surface.
The thickness of the hydrate zone is determined by the geothermal gradient, or how fast
the Earth warms with depth. Combined information from Arctic gas-hydrate studies shows
that, in permafrost regions, gas hydrates may exist at subsurface depths ranging from
about 130 meters to 2,000 meters. Direct evidence for gas hydrates on the North Slope of
Alaska comes from cores and petroleum industry well logs, which suggest the presence of
numerous gas hydrate layers in the area of the Prudhoe Bay and Kuparuk River oil fields.
Currently, there is no commercial development of methane hydrates with the possible
exception of the Messoyakha gas field on the eastern margin of the West Siberian basin, in
which some increased gas pressure since conventional production first began may be
attributed to dissociation of surrounding hydrates.
Methane hydrate is also stable in ocean floor sediments at water
depths greater than 500 meters. Where hydrates occur they are known to cement loose
sediments into a layer several hundred meters thick. Most of the methane hydrate
accumulations are expected to be in sea floor deposits along continental margins. When
hydrates were first encountered by the offshore oil industry in the 1970s, they were
viewed primarily as a curiosity. Since then, oil and gas production has advanced into
water depths deep enough to have significant amounts of methane hydrates in the sea floor.
The world's currently known natural gas reserves are estimated at
5,000 trillion cubic feet. The amount of methane contained in the world's gas hydrate
accumulations is enormous. Estimates of the amounts are speculative and range over three
orders of magnitude from about 100,000 trillion cubic feet to 279,000,000 trillion cubic
feet of gas. Despite the enormous range of these estimates, gas hydrates seem to be a much
greater resource of natural gas than conventional accumulations. However, it is likely
that most of the hydrate occurs in low concentrations and has no commercial potential.(1) The goal of a research program would
be to find locations where the methane hydrates are sufficiently concentrated to warrant
commercial interest, in addition to proving the technological feasibility and safety of
In 1995, the U.S. Geological Survey (USGS) completed a systematic
appraisal of the in-place natural gas hydrate resources of the United States, both onshore
and offshore. The mean (expected value) is estimated to be 320,000 trillion cubic feet of
gas. This assessment did not address the problem of hydrate recovery. Subsequent
refinements of the data in 1997, using information from the Ocean Drilling Program, have
suggested that the mean should be adjusted slightly downward, to around 200,000 trillion
cubic feet. For comparison, the estimated conventional gas resources and reserves in the
United States are 1,400 trillion cubic feet. If it could be safely and economically
recovered, one 50 by 150 kilometer area off the coast of North and South Carolina is
estimated to hold enough methane to supply the needs of the United States for over 70
Sea floor stability and safety are two important issues related to
gas hydrates. Sea floor stability refers to the susceptibility of the sea floor to
collapse and slide as the result of gas hydrate disassociation. The safety issue refers to
petroleum drilling and production hazards that may occur in association with gas hydrates
in both offshore and onshore environments. The safety issue affects current oil and gas
production as well as being of concern to possible hydrate development in the future.
Throughout the world, oil and gas drilling is moving into regions
where safety problems related to gas hydrates may be anticipated. Oil and gas operators
have recorded numerous drilling and production problems attributed to the presence of gas
hydrates, including uncontrolled gas releases during drilling, collapse of well casings,
and gas leakage to the surface. In the marine environment, gas leakage to the surface
around the outside of the well casing may result in local sea floor subsidence and the
loss of support for foundations of drilling platforms. These problems are generally caused
by the dissociation of gas hydrate due to heating by either warm drilling fluids or from
the production of hot hydrocarbons from depth during conventional oil and gas production.
Subsea pipelines may also be affected by loss of sea floor support from hydrates
destabilized by warming.
Hazards arise because gas hydrates are only quasi-stable; if the
temperature is increased at a fixed pressure or the pressure decreased at fixed
temperature, or both temperature increased and pressure decreased, it is easy to pass out
of the stability regime of hydrates. The hydrate structure encases methane at very high
concentrations. A single unit of hydrate, when heated and depressurized, can release 160
times its volume in gas. It is possible that both natural and human-induced changes can
contribute to in-situ gas hydrate destabilization, which may convert an offshore
hydrate-bearing sediment to a gassy water-rich fluid, triggering sea floor subsidence and
catastrophic landslides. Evidence implicating gas hydrates in triggering sea floor
landslides has been found along the Atlantic Ocean margin of the United States.(2) The mechanisms controlling gas
hydrate-induced sea floor subsidence and landslides are not well known, but these
processes may release large volumes of methane to the Earth's oceans and atmosphere.
Methane is a "greenhouse" gas, 10 times more effective than carbon dioxide in
the process believed by many to cause climate warming.
In 1981, a drill core containing methane hydrate was recovered on a
National Science Foundation-sponsored scientific drilling program. Studies of this core
led to federal efforts to investigate gas hydrates. From 1982 to 1992, the Department of
Energy (DOE) spent $8 million to develop a foundation of basic knowledge about the
location and thermodynamic properties of methane hydrates. DOE's initial methane hydrate
research ended in 1992 as priorities shifted at that time to more near-term and immediate
exploration and production R&D.
In 1997, the Energy Research and Development Panel of the
President's Committee of Advisors on Science and Technology (PCAST) recommended that DOE
begin a major 5-year, $44 million initiative to work with the U.S. Geological Survey, the
Mineral Management Service, the Naval Research Lab, and industry to evaluate the
production potential of methane hydrates in U.S. coastal waters and worldwide.(3) In FY 1997 and FY 1998, DOE provided a
small amount of funding from its Natural Gas Supply Program to support limited R&D
activities on methane hydrates. In FY 1999, DOE allocated $.51 million specifically for
methane hydrate research. For FY 2000 the Department requested $1.985 million for that
research and Congress appropriated $2.96 million. DOE's budget request for FY 2001
includes $2.00 million for methane hydrate research
Late in the 105th Congress, the Senate passed The Methane
Hydrate Research and Development Act, and hearings were held in the House, but Congress
adjourned before further action could be taken. The legislation was reintroduced into the
106th Congress (S.
330) and reported from the Committee on Energy and Natural Resources on March 22, 1999
The Senate passed S. 330
on April 19, 1999. The legislation directs the Secretary of Energy to coordinate an
interagency research and development program to develop methane hydrate resources. In
doing so, the Secretary of Energy is directed to consult with the Secretaries of Defense,
Interior, and the Director of the National Science Foundation. The bill did not specify
funding levels, but authorized the appropriation of such available discretionary funds as
are necessary to carry out the methane hydrate R&D program. Based on information in
DOE's 1998 program plan for methane hydrates, the Congressional Budget Office (CBO)
estimated this activity would require appropriations totaling about $45 million over the
next 5 years and outlays totaling $35 million over the next 5 years.(4) While the legislation would not give DOE authority it does
not already have, it would provide a clear endorsement from Congress of federal and
cooperative research efforts to understand better the energy potential of methane
hydrates. The Administration is reported to support the measure.(5)
On May 11, 1999, H.R. 1753 was introduced
into the House and referred to both the Committee on Science and the Committee on
Resources. The bill differed from the Senate bill primarily in authorizing funding of $42
million over five years. As introduced, H.R. 1753 authorized
appropriations of $5 million for FY 2000, $7.5 million for FY 2001, and $10 million for
each of fiscal years 2002 through 2004. Both committees ordered the bill to be reported
with a number of amendments (H.Rept. 106-377,
Parts I and II). The House passed the bill on October 26, 1999 funding the research
program at $47.5 million over a 5-year period in the amounts of $5, 7.5, 11, 12, and 12
million for FY 2000 through FY 2004 respectively. The Senate passed H.R. 1753 as amended on
November 19, 1999. Among the differences, the House-passed bill would terminate the
program at the end of fiscal year 2004, whereas the Senate-passed bill would continue the
program thereafter with such sums as necessary.
H. Johnson, Senior Staff Geologist, Chevron USA Production Co., testimony before the House
Committee on Science, Subcommittee on Energy and Environment, Hearing on S. 1418: The Methane
Hydrate Research and Development Act, September 15, 1998, unpublished. See also http://www.hydrate.org/resources.htm.
2. (back)M. D.
Max and W. P. Dillon, "Oceanic Methane Hydrate: The Character of the Blake Ridge
Hydrate Stability Zone, and the Potential for Methane Extraction," Journal of
Petroleum Geology, vol. 21, no. 3, July 1998, 343-357.
Committee of Advisors on Science and Technology, Energy Research and Development Panel, Federal
Energy Research and Development Challenges of the Twenty-First Century, November
1997. See http://www.whitehouse.gov/WH/EOP/OSTP/Energy/.
Committee on Science, Subcommittee on Energy and Environment, S. 1418: The Methane
Hydrate Research and Development Act, 105th Congress, 2nd
sess., September 15, 1998, 13.
Ann Duncan, "Senate Energy to act on leftovers from 1998," Congressional
Green Sheets Weekly Bulletin, March 1, 1999, 12-14. See also House Committee on
Science, Subcommittee on Energy and Environment, S. 330 and H.R.. 1753, The Methane
Hydrate Research and Development Act of 1999, 106th Congress, 1st
sess., May 12, 1999, 28.