Dr. Timothy S. Collett
House Committee on Resources
Subcommittee on Energy and Mineral Resources
Unconventional Fuels II: The Promise of Methane Hydrates
July 30, 2009
Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to discuss the importance of the energy resource potential of natural gas hydrates.In this statement I will discuss the USGS assessment of the energy resource potential of natural gas hydrates and examine the research and development issues that need to be resolved to safely and economically produce gas hydrates. It is important to note that many different gases form gas hydrates, but methane, which is the main component of natural gas and is used to heat homes and for other domestic purposes, is the most common gas included in gas hydrates and that is why they are often referred to as methane hydrates.It is also important to note that this testimony will focus on the technical and economic aspects of gas hydrate production potential.The environmental impacts from gas hydrate production, including the potential impacts on global climate change, require additional study and analysis as the role of gas hydrates in the total energy mix is further defined and considered.
In 1995, USGS made the first systematic assessment of the in-place natural gas hydrate resources of the
Gas Hydrate Occurrence and Characterization
Gas hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-lattice holds gas molecules in a cage-like structure.The gas and water become a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone.Gas hydrates are widespread in Arctic regions beneath permafrost and beneath the seafloor in sediments of the outer continental margins.The amount of gas contained in the world's gas hydrate accumulations is enormous, estimates of in-place gas within natural gas hydrates range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet (TCF) of gas.By comparison, the conventional global gas endowment (undiscovered, technically recoverable gas resources + conventional reserve growth + remaining reserves + cumulative production) has been estimated at approximately 15,400 TCF (USGS World Petroleum Assessment, 2000). Despite the enormous range of these estimates, and the notable differences between in-place gas-hydrate estimates and the aforementioned estimates of conventional gas, gas hydrates seem to be a much greater resource of natural gas than conventional accumulations.
Even though gas hydrates are known to occur in numerous marine and Arctic settings, relatively little is known about the geologic controls on their distribution.The presence of gas hydrates in offshore continental margins has been inferred mainly from anomalous seismic reflectors that coincide with the base of the gas-hydrate stability zone.This reflector is commonly called a bottom-simulating reflector or BSR.BSRs have been mapped at depths ranging from about 0 to 1,100 meters below the sea floor.Gas hydrates have been recovered by scientific drilling along the Atlantic, Gulf of Mexico, and Pacific coasts of the
Onshore gas hydrates have been found in Arctic regions of permafrost and in deep lakes such as
The USGS 1995 National Assessment of United States Oil and Gas Resources focused on assessing the undiscovered conventional and unconventional resources of crude oil and natural gas in the
In the fall of 2008, the USGS completed the first-ever resource estimate of technically recoverable gas from natural gas hydrates.That study found that there is 85.4 TCF (mean value) of technically recoverable gas in gas hydrates on the North Slope of Alaska.This assessment indicates the existence of technically recoverable gas hydrate resources ― that is, resources that can be discovered, developed, and produced using current technology.The area assessed in northern
In anticipation of gas hydrate production in Federal waters, the U.S. Minerals Management Service (MMS) has recently launched a project to assess gas hydrate energy resource potential on acreage under MMS jurisdiction.The MMS is currently working to assess the resource potential of gas hydrate on the Atlantic OCS and to address the technical recoverability of gas hydrate in the marine environment.Early in 2008, MMS reported on their systematic geological and statistical assessment of in-place gas hydrate resources in the Gulf of Mexico OCS.This assessment integrated the latest findings regarding the geological controls on the occurrence of gas hydrate and the abundant geological and geophysical data from the
Gas Hydrate Production
Gas recovery from hydrates is a challenge because the methane is in a solid form and because hydrates are usually widely dispersed in frontier areas such as the
The pace of gas hydrate energy projects has accelerated over the past several years.Researchers have long speculated that gas hydrates could eventually be a commercial resource, yet technical and economic hurdles have historically made gas hydrate development a distant goal rather than a near-term possibility.This view began to change over the past five years with the realization that this unconventional resource could be developed in conjunction with conventional gas fields and with existing technology.Research coring and seismic programs carried out by the Ocean Drilling Program (ODP), Integrated Ocean Drilling Program (IODP), government agencies, and several consortia have significantly improved our understanding of how gas hydrates occur in nature and have verified the existence of highly concentrated gas hydrate accumulations at several locations.The most significant development was the production testing conducted at the Mallik site in
It is recognized that the Mallik 2002 project contributed much to the understanding of gas hydrates; however, it fell short of delivering all of the data needed to fully calibrate existing reservoir simulators.It was also determined that longer duration production tests would be required to assess more definitively the technical viability of long-term production from gas hydrates.The 2006-2008 Mallik Gas Hydrate Production Research Program was conducted by the Japan Oil Gas and Metals National Corporation (JOGMEC), Natural Resources Canada (NRCan), and the Aurora College/Aurora Research Institute to build on the results of the Mallik 2002 project with the main goal of monitoring long-term production behavior of gas hydrates.The primary objective of the 2006-2007 winter field activities was to install equipment and instruments to allow for long term production gas hydrate testing during the winter of 2007-2008.The following winter (2007/2008), the team returned to the site to undertake a longer-term production test.The 2007/2008 field operations consisted of a six day pressure drawdown test, during which "stable" gas flow was measured.The 2007/2008 testing program at Mallik established a continuous gas flow ranging from about 70,000 to 140,000 ft3/day, which was maintained throughout the course of the six-day (139-hour) test as reported by JOGMEC, NRCan, and the Aurora College/Aurora Research Institute. The 2006-2008 Mallik production test is a significant event in our understanding of gas production from hydrates, in that "sustained" gas production from hydrates was achieved with existing conventional technology through simple well depressurization alone.
The potential for gas hydrates as an economically viable resource has been impacted by higher natural gas prices and forecasts of future tighter supply. However, gas hydrates have yet to be produced economically on a large scale. Gas hydrates have been compared to other unconventional resources, which were also considered to be uneconomic in the not too distant past, such as coalbed methane and tight gas sands.Once those resources were geologically understood and production challenges were addressed, these unconventional resources became part of the nation's energy mix.
Safety and Seafloor Stability
Safety and seafloor stability are two important issues related to gas hydrates.Seafloor stability refers to the susceptibility of the seafloor to collapse and slide as the result of gas hydrate dissociation.The safety issue refers to petroleum drilling and production hazards that may occur in association with gas hydrates in both offshore and onshore environments.
Under the ocean floor, the depth to the base of the gas hydrate stability zone becomes shallower as water depth decreases and the base of the gas hydrate stability zone intersects the seafloor at about 1,500 ft, a depth characterized by generally steep topography on the continental slope.It is possible that both natural and human induced changes can contribute to in-situ gas hydrate destabilization by changing the pressure or temperature regime, which may then convert hydrate-bearing sediments to a gassy water-rich fluid, triggering seafloor landslides.Evidence implicating gas hydrates in triggering seafloor landslides has been found along the Atlantic Ocean margin of the
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 described numerous drilling and production problems attributed to the presence of gas hydrates, including uncontrolled gas releases during drilling, collapse of wellbore casings, and gas leakage to the surface.In the marine environment, gas leakage to the surface around the outside of the wellbore casing may result in local seafloor 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 warm hydrocarbons from depth during conventional oil and gas production.The same problems of destabilized gas hydrates by warming and loss of seafloor support may also affect subsea pipelines.
National Research Agenda for Gas Hydrate Energy Development
In 1982, scientists onboard the Research Vessel Glomar Challenger retrieved a three-ft-long sample of massive gas hydrate off the coast of
Recognizing the importance of gas hydrate research and the need for coordinated effort, the U.S. Congress enacted Public Law 106-193, the Methane Hydrate Research and Development Act of 2000.The Act called for the Secretary of Energy to begin a methane hydrate research and development program in consultation with the National Science Foundation; the U.S. Departments of Commerce, represented by the National Oceanographic and Atmospheric Administration (NOAA); Defense, represented by Naval Research Laboratory; and Interior, represented by USGS and MMS.In August, 2005, the Act was reauthorized through 2010 as Sec. 968 of the Energy Policy Act of 2005 (Public Law 109-58), and the Bureau of Land Management (BLM) was added to the interagency effort.
It is important to highlight that for two decades prior to this Act the bureaus of the Department of Interior studied gas hydrates within their various missions using base research funds.This base funded research continues, but in partnership with a variety of organizations.The USGS is investigating many aspects of gas hydrates to understand their geological origin, their natural occurrence, the factors that affect their stability, the environmental impact and the possibility of using this vast resource in the world energy mix.The USGS is investigating the resource potential of gas hydrates around the world in partnership with many organizations:(1) in the Mackenzie Delta of Canada in partnership with an international consortium; (2) on the North Slope of Alaska in partnership with DOE and BP Exploration (Alaska); (3) the DOE/ConocoPhillips gas hydrate production by CO2 sequestration project, (4) in the U.S. Gulf of Mexico Joint Industry Partnership (JIP) with Chevron, DOE, and others; (5) the DOE/North Slope Borough, Alaska project; (6) in India in partnership with the Indian Directorate General of Hydrocarbons; and (7) Ocean Drilling Program (ODP) Leg 204 and Integrated Ocean Drilling Program (IODP) Expedition 311.Other countries and groups have expressed interest in cooperative activities including
A major emphasis of USGS research focuses on the North Slope of Alaska, where USGS is participating in several gas hydrate energy research projects with DOE, BLM and various industry partners. The USGS is analyzing the recoverability and potential production characteristics of onshore natural gas hydrate accumulations overlying the Prudhoe Bay,
Another major emphasis of USGS research is the U.S. Gulf of Mexico.Several Gulf of Mexico hydrate research programs are underway and the most comprehensive study is a Joint Industry Project (JIP) led by DOE in partnership with Chevron which is designed to further characterize gas hydrates in the
On May 6, 2009, the JIP, including DOE, USGS, and MMS research scientists, completed the first-ever drilling project with the expressed goal to collect geologic data on gas-hydrate-bearing sand reservoirs in the
The two holes drilled at
Seismic-acoustic imaging to identify gas hydrate and its effects on sediment stability has been an important part of USGS marine and onshore studies since 1990.USGS work in this area has allowed for prediction of the occurrence as well as the thickness and saturation of gas hydrates ahead of drilling.USGS has also conducted extensive geochemical surveys and established a specialized laboratory facility to study the formation and dissociation of gas hydrate in nature and also under simulated deep-sea conditions.
The USGS, as well as many groups, participate in the IODP, the ODP, and their predecessor the Deep Sea Drilling Project (DSDP) – which have contributed greatly to our understanding of the geologic controls on the formation, occurrence, and stability of gas hydrates in marine environments.The gas hydrate research efforts under IODP-ODP-DSDP have been mostly directed to assess the role of gas hydrate in climate change.In the summer of 2002, ODP Leg 204 investigated the formation and occurrence of gas hydrates in marine sediments at Hydrate Ridge off the
BP Exploration (Alaska), DOE, and the USGS have undertaken a project to characterize, quantify, and determine the commercial viability of gas hydrates and associated free gas resources in the Prudhoe Bay, Kuparuk River, and Milne Point field areas in northern Alaska.Under Phase 1 of this project, gas hydrates and associated free gas-bearing reservoirs in the Milne Point oil field have been studied to determine reservoir extent, stratigraphy, structure, continuity, quality, variability, and geophysical and petrophysical property of these hydrocarbon-bearing reservoirs. The objective of Phase 1 is to characterize reservoirs and fluids, leading to estimates of the recoverable gas reserve and commercial potential, and the definition of procedures for gas hydrate drilling, data acquisition, completion, and production. Phases 2 and 3 will integrate well, core, log, and production test data from additional test wells. Ultimately, the program could lead to development of a gas hydrate pilot project with a long term production test, and determine whether gas hydrates can become a part of the Alaska North Slope gas resource portfolio. In 2005, extensive analysis of 3-D seismic data and integration of that data with existing well log data by the USGS identified more than a dozen discrete and mappable gas hydrate prospects within the Milne Point area.Because the most favorable of those targets was a previously undrilled, fault-bounded accumulation, BP Exploration (Alaska) and DOE decided to drill a vertical stratigraphic test well at that location (named the "Mount Elbert" prospect) to acquire critical reservoir data needed to develop a longer term production testing program.The
International Gas Hydrate Research and Development Efforts
Many countries are interested in the energy resource potential of gas hydrates. Countries including
In 1995, the Government of Japan established the first large-scale national gas hydrate research program, which now plays a leading role in worldwide gas hydrate research efforts.The first five years of the Japan National Gas Hydrate Program culminated in 1999/2000, with the drilling of a series of closely spaced core and geophysical logging holes in the Nankai Trough.In 2001, the Ministry of Economy, Trade and Industry (METI) launched a more extensive project entitled "
The government of
Production Potential of Gas Hydrates – Technical Challenges
In order to release, or produce, the gas from a gas hydrate, we must change the temperature or pressure conditions controlling its occurrence and stability.The most economically promising method of producing gas from gas hydrates appears to be depressurization of the reservoir.Results from the Mallik and
The timing for expected commercial production of hydrates is uncertain.The DOE has estimated that gas production from gas hydrate could begin no earlier than 2015.In September of 2003, the National Petroleum Council (NPC) reported that we will not likely see significant production from gas hydrates until sometime beyond 2025.Initial production from gas hydrates could occur much sooner, especially in areas such as the North Slope of Alaska or in other countries.Estimates vary on when gas hydrate production will play a significant role in the total world energy mix.It is not currently possible to determine whether hydrates will be able to contribute to the domestic energy supply. The future contribution of this resource will depend not only on further progress in gas hydrate production, but also on research into the environmental impacts of gas hydrate production, which are not fully understood.
Next Steps to Gas Hydrate Production
The immense volume of gas hydrates worldwide may be a significant potential energy resource at some point in the future.Our understanding of these resources, however, is still evolving – we do not yet know if these accumulations exist in sufficient concentration to make them economically viable, nor do we know whether even concentrated accumulations can be developed economically.Additional science-driven production tests will contribute to our understanding of gas hydrate production.It is generally believed that gas hydrates can be produced by standard techniques used today to exploit conventional oil and gas resources. However, it is very likely that new drilling and production technology would contribute to the ultimate producibility of gas hydrates.We know that hydrates must be produced by releasing the gas from the hydrate form by the methods previously described.However, there has only been one industry scale hydrate production test to date (the 2008 Mallik project).Much more information is needed on: (1) the geology of the hydrate-bearing formations, both on a large scale (the the distribution of hydrates throughout the world) and on a small scale (their occurrence and distribution in various host sediments); (2) the reservoir properties/characteristics of gas hydrate reservoirs; (3) the production response of various gas hydrate accumulations; and (4) the economics controlling the ultimate resource potential of gas hydrates.The USGS will continue to play a vital role in studying, evaluating, and understanding the geologic and engineering properties critical to the realization of hydrates as a viable energy source.The USGS will also continue to work with other Federal agencies and within domestic and international consortiums to conduct needed gas hydrate production test studies.
Our knowledge of naturally occurring gas hydrates is growing and it can be concluded that: (1) a huge volume of natural gas is estimated to be stored in gas hydrates; (2) production of natural gas from gas hydrates is technically feasible with existing technology; (3) gas hydrates hold the potential for natural hazards associated with seafloor stability and release of methane to the oceans and atmosphere; and (4) gas hydrates disturbed during drilling and petroleum production pose a potential safety problem.USGS research on gas hydrates is focused on: (1) the energy-resource potential they represent; (2) the hazards they might pose to drilling and the environment; and (3) the impact they might have on global climate change. Thus, the USGS welcomes the opportunity to collaborate with domestic and international scientific organizations and industry to further collective understanding of these important geologic materials.
Thank you, Mr. Chairman for the opportunity to present this information.I will be happy to respond to any questions you may have.