Andrew McBarnet points to the signs that indicate previous enthusiasm for gas hydrate research in the US may be running out of steam.
The announcement last month of significant progress in a key gas hydrates research project offshore Japan featuring some US participation scarcely made it into the oil industry news cycle. The scant coverage suggests that interest in the promise of gas hydrates as a major future energy source for the US has once again been consigned to the back burner. This is despite the massive potential resource availability in the US.
In 2008, the US Minerals Management Service, now the Bureau of Ocean Energy Management (BOEM), suggested that there were about 11,00034,000Tcf of methane inplace in hydrate form in the northern Gulf of Mexico, with a mean value of 21,444Tcf. The assessment made no estimate of how much of this was technically or economically recoverable, but did comment that about 6700Tcf of the resource occurs in relatively high concentration accumulations in sandy sediments which would be most likely producible Subsequently, in 2011, BOEM released some new estimates for the lower 48 US Outer Continental Shelf, but the volumes of possible gas remain huge. Also, in 2008, the US Geological Survey (USGS) estimated that there is approximately 85Tcf of undiscovered, but technically recoverable, natural gas resource in sediments within and beneath the permafrost on the North Slope of Alaska.
According to a National Energy Technology Laboratory (NETL) briefing, the figures compare with the total US natural gas resource,excluding hydrates,amounting to 2074Tcf,based on estimates reported by the Potential Gas Committee. It says,‘If one third of the natural gas inplace in methane hydrate insandy sediments of the Gulf of Mexico becomes technically recoverable,the US could double its total natural gas resource.’
Any incentive to step upinvestment in the currentmodest research efforts to explore the potential value of gas hydrates to the US energy mix appear to have been sapped more than anything by the large scale exploitation of the North American shale gas plays in the last few years, likely to be replicated in other parts of the world. This unpredicted turn of events has transformed thinking about the US energy balance over the next few decades leaving gas hydrates somewhat out of the calculations.
However, there are some countries in the world, not just Japan, where any advance in understanding of gas hydrates is likely to cause at least a flicker of excitement. China, Korea, and India, for example, all face major challenges to meet energy demand from indigenous sources, driven by rapid economic growth and increasing home consumption. They are all hanging some of their hopes on gas hydrates, and have been accelerating their efforts in this department. So, the implications of the latest results from Japan will be closely watched in some quarters.
The project in question is an ongoing program in the deepwater Nankai Trough, offshore Japan. After an initial success with the 1999/2000 Nankai Trough Project, in 2001, the Ministry of Economy, Trade & Industry (METI) launched a new major project entitled ‘Japan’s Methane Hydrate Exploitation Program,’ operated by the Methane Hydrate 2001 Consortium (also known as MH21), to evaluate the resource potential of deepwater gas hydrates in the Nankai Trough area, much like the goals of the previous Nankai Trough project. The project is intended to go much further and promote the technical development and recovery of gas hydrate, and to provide a long term stable energy supply to Japan. On behalf of METI, the Japan Oil Gas & Metals National Corporation (JOGMEC) and the Agency of Industrial Science & Technology (AIST) have developed a highly integrated gas hydrate research and development program including both basic research and field studies. This program is now built around an 18-year plan to be completed in 2018 (initially planned as a 16-year program but the goals of this effort were revised in 2008).
In fact, US scientists have got a finger on the pulse of this most advanced gas hydrate program in the world, thanks to ongoing collaboration on methane hydrate research through the US Department of Energy (DOE) and the Gulf of Mexico Gas Hydrate Joint Industry Project (JIP). In this particular segment of the Japanese project, the US Gas Hydrate Project (part of USGS) and the School of Civil & Environmental Engineering at Georgia Tech have played a key role.
The latest achievement has been the successful borehole recovery of sediment containing gas hydrates – pressure cores – delivered with new technology designed to allow scientist to better study the gas hydrates in lab conditions, preserved as they were in their natural state in the subsurface where they occur. Gas hydrates, for those unfamiliar, are defined as ice-like substances formed when methane, and sometimes other gases, combine with water at specific intermediate temperatures and low temperature. They are found in the marine sediments beneath the ocean floor on the edge of continental shelves and in sediments within and beneath permafrost areas. It is the pressure-temperature conditions that keep the gas hydrates stable, ie intact with the gases contained in a solid form.
The pressure sampling in the Eastern Nankai Trough is part of a reservoir characterization project, ahead of a first production test planned for this year. The test site is in 1000m water depth, where the first exploratory campaign, begun nearly 10 years ago, identified turbiditic sediments, several tens of meters thick, containing concentrated methane hydrate some 300m below the seabed. As reported by JOGMEC and AIST, a dedicated borehole was drilled, in 2012, in addition to part of a production well and two temperature monitoring boreholes. The purpose was to recover pressure cores for research from a number of multidisciplinary perspectives including geological, geochemical/mechanical, microbiological, and petrophysical.
The pressure core recovery itself was not new, although some improvements were made to the system. However, some of the cores preserved under pressure will be analyzed using, for the first time, pressure core characterization tools (PCCTs) developed by Georgia Tech and operated in conjunction with USGS. The university designed its first gas hydrate research equipment, the Instrumented Pressure Testing Chamber (IPTC), in 2004, under the auspices of the DOE/ Chevron Gulf of Mexico JIP to measure seismic, strength, and electrical properties of hydrate bearing sediments recovered in pressure cores. This innovation was employed in conjunction with the Pressure Core Analysis & Transfer System (PCATS), designed by UK company Geotek, which can transfer cores through an X-ray CT scanner for nondestructive measurements of density and p-wave velocities. The IPTC/PCAT tools were in operation for the Gulf of Mexico JIP Leg 1 expedition, offshore India, as part of India’s Natural Gas Hydrate Program, and offshore Korea for sampling by Ulleung Basin Gas Hydrate Program.
This year’s production test already underway is the first of its kind, and is a big deal for Japan, and arguably for the world, as the first marine test. It helps to put the country on the path to developing technology that can produce viable quantities of gas from hydrates. Commercially it may not make a lot of sense in current market conditions, but strategically this may be important for Japan, especially now that the nuclear option is most unlikely to be considered.
Dr Carolyn Ruppel, USGS gas hydrates project chief, says: “We are just pleased that we have been able to collaborate with our Japanese colleagues on one component of this important development in gas hydrate research.”
Gulf of Mexico research
In different circumstances the first offshore production test on the scale envisaged might have taken place in the Gulf of Mexico. Following various US and international test projects in the 1990s, gas hydrate research picked up momentum in the US following the Methane Hydrate R&D Act of 2000. This enabled DOE to involve industry, academia, DOE labs, and six federal agencies, of which USGS was one, in dedicated research projects.
Such research has traditionally been broken down into three broad areas of interest: 1) the energy resource potential; 2) possible effects of gas hydrate ‘disassociation’ on climate change; and 3) the geohazards.
In fact the Gulf of Mexico JIP Leg 1 offshore expedition in 2005 addressed the potential geohazards posed by gas hydrates in fine-grained sediments for deepwater exploration and production operations. The theory was that commercial activities that disrupt hydratebearing sediments or sediments charged with free gas beneath the gas hydrate stability zone (GHSZ) could encounter numerous potential hazards.
Essentially the conclusion was that the industry already had the issue pretty much covered, and many of the possible drilling scenarios had already been encountered and successfully managed.
Focus of the second Gulf of Mexico JIP Leg 2, in 2009, was designed to expand the understanding of gas hydrate in the Gulf of Mexico by specifically targeting systems thought to include highquality (thick, porous, and permeable) sands. These are the most likely to contain good concentrations of gas hydrate.
Results from this expedition supported the predicted potential of gas hydrate as an energy resource. Gas hydrate was found at saturations ranging from 50% to more than 90% in high-quality sands.
The drilling (and logging-while-drilling) at Walker Ridge block 313 and Green Canyon block 955 discovered the most promising marine gas hydrate accumulations in the world, according to Dr Timothy Collett, co-leader of the expedition from USGS, who has spent most of his career on research into gas hydrates as a potential energy resource.
Scientific results from this second Gulf of Mexico field trip have all been published, but the intervening years since the 2009 initiative seem to have put the brakes on momentum for further major initiatives. For example, there is no talk of moving to prepare a production test which would be the logical follow-on from JIP Leg 2, probably preceded by a test in Alaska. It has been announced that no further drilling is planned. This implies lack of support from oil companies, who would be an essential partner in any further work. A number of factors seem to have coalesced against raising the tempo of research. A tanking economy at the time didn’t help, nor did the Macondo incident, in 2010, which undoubtedly brought all oil companies’ risk adverse instincts to the fore, and made gas hydrates seem an unnecessary journey into uncertainty. All this, and the advent of shale gas opportunities: it could hardly fail to engender an attitude of ‘why bother?’.
The DOE and the USGS continue to work with BP, and a team of participants from industry, government, and academia, to evaluate and test the producibility of methane from hydrate in Arctic Alaska. A Mount Elbert stratigraphic test well, drilled in 2007, confirmed the existence of 60-75% hydrate saturation within reservoir quality sands in targeted stratigraphic intervals. A short-term downhole test proved the ability of the formation to release gas through depressurization, the first time this had been accomplished on the North Slope.
The DOE has also partnered with ConocoPhillips and JOGMEC to conduct a test of natural gas extraction from methane hydrate using a production technology, developed through laboratory collaboration between the University of Bergen, Norway, and ConocoPhillips, for the 2012 Ignik Sikumi Gas Hydrate Field Test in Arctic Alaska. The team injected a mixture of carbon dioxide and nitrogen into the formation, and demonstrated that this mixture could promote the production of natural gas. This test is said to have been the first ever field trial of a methane hydrate production methodology, whereby CO2 was exchanged in situ with the methane molecules within a methane hydrate structure. Results of the depressurization phase of this project are being used to design the long term gas hydrate production test planned for Alaska. However, it is understood that ConocoPhillips will not be continuing its involvement in this project, citing among other things the shale gas priority.
It is pretty obvious from the last round of DOE funding, in 2012, that gas hydrate research does not rate as a high priority on the Obama Administration’s ‘all of the above’ policy to maximize development of US energy resources. A total of $5.5 million is being spent on 14 new research projects under the supervision of NETL. Admittedly, this is in addition to ongoing project funding for gas hydrate research by DOE and a number of government agencies, but it is not a lot of money. Six of these are designed to capitalize on the reservoir characterization field work undertaken during the Gulf of Mexico JIP Leg 2, in 2009. Several other projects are aimed at further study of the nature and occurrence of gas hydrate in settings impacted by changing climates. This interest seems partly a response to the alarmist school of environmentalists, who insist that our warming climate could cause gas hydrates in the Arctic environment to break down (dissociate), releasing the methane that they now trap.
While acknowledging the need for further research, Dr Ruppell does not go along with this type of catastrophic scenario. She and colleagues have argued that only a fraction of all likely gas hydrate deposits are found within or beneath permafrost. The top of the gas hydrate stability zone in areas of thick permafrost typically lies at greater than 200m depth, and these permafrost-associated gas hydrates are expected to be stable for thousands of years under most climate warming scenarios.
The subset of permafrost-associated gas hydrates that occurs in shallow, unglaciated, circum-Arctic Ocean shelves lies at the same depths. The prevailing conditions may render these gas hydrates more susceptible to warming-driven dissociation, but the timescales involved and factors that mitigate the release of this methane to the atmosphere make it unlikely that there will be an Arctic methane catastrophe attributable to destabilization of methane hydrates, according to Dr Ruppel.
Such debates are just one other indication that gas hydrate study in the US has, for the time being, returned to its home in the academia after its brief foray into the mainstream through oil industry support. OE