US and Japan successfully complete Arctic field trial of gas hydrate production technology using CO2-methane exchange within structure
|Conceptual rendering of CO2 – CH4 exchange methodology for the production of natural gas from hydrates. Source: NETL. Click to enlarge.|
US Energy Secretary Steven Chu announced the completion of a successful test of technology in the North Slope of Alaska that was able to safely extract a steady flow of natural gas from methane hydrates. Methane hydrates are 3D ice-lattice structures with natural gas locked inside, and are found both onshore and offshore—including under the Arctic permafrost and in ocean sediments along nearly every continental shelf in the world.
The US Department of Energy (DOE) partnered with ConocoPhillips and the Japan Oil, Gas and Metals National Corporation (JOGMEC) on the test, which was the first field trial of a methane hydrate production methodology whereby CO2 was exchanged in situ with the methane molecules within a methane hydrate structure. The production technology was developed through laboratory collaboration between the University of Bergen, Norway, and ConocoPhillips.
Observations about the process made during laboratory testing include:
Rapid rates of CO2-CH4 exchange in hydrates formed in porous media under a range of initial conditions;
The efficiency of the carbon dioxide displacing the methane from the hydrate structure approaches theoretical limits;
The preservation of measurable permeability in the porous media during hydrate formation and exchange; and, most importantly,
The exchange process does not involve the release of free water to the pore system.Instead, the process appears to dissociate and re-form hydrate at very fast rates and on a micro-scale in such a manner that there is no free water formed or significant heat-of-reaction issues.
As part of this exchange demonstration, the depressurization phase of the test extended for 30 days. The prior longest-duration field test of methane hydrate extraction via depressurization was six days (Japan-Canada 2007/2008 Mallik well testing program).
Building upon this initial, small-scale test, the US Department of Energy (DOE) is launching a new research effort to conduct a long-term production test in the Arctic as well as research to test additional technologies that could be used to locate, characterize and safely extract methane hydrates on a larger scale in the US Gulf Coast.
The Energy Department’s long term investments in shale gas research during the 70s and 80s helped pave the way for today’s boom in domestic natural gas production that is projected to cut the cost of natural gas by 30 percent by 2025 while creating thousands of American jobs. While this is just the beginning, this research could potentially yield significant new supplies of natural gas.—Secretary Chu
The ongoing, proof-of-concept test commenced on 15 February 2012, and concluded on 10 April. The team injected a mixture of carbon dioxide (CO2) and nitrogen into the formation, and demonstrated that this mixture could promote the production of natural gas. Ongoing analyses of the extensive datasets acquired at the field site will be needed to determine the efficiency of simultaneous CO2 storage in the reservoirs.
This testing will provide critical information to advance DOE’s efforts to evaluate various potential gas hydrate production technologies. The next stages of the Department’s research effort will be aimed in part at evaluating gas hydrate production over longer durations, likely through depressurization, with the eventual goal of making sustained production economically viable.
A New Research Effort. DOE announced two major new steps in the overall methane hydrate research effort:
DOE is making $6.5 million available in Fiscal Year 2012 Funding Opportunity Announcement for research into technologies to locate, characterize and safely extract natural gas from methane hydrate formations like those in the Arctic and along the US Gulf Coast.
Specifically, projects will address (1) deepwater gas hydrate characterization via direct sampling and/or remote sensing field programs; (2) new tools and methods for monitoring, collecting, and analyzing data to determine reservoir response and environmental impacts related to methane hydrate production; and (3) clarifying methane hydrates role in the environment, including responses to warming climates.
As part of the President’s budget proposal for Fiscal Year 2013, the Department is requesting an additional $5 million to further gas hydrates research both domestically, and in collaboration with international partners. The exact nature of that research effort will be determined in the coming months; however, a longer duration test of methane hydrate extraction on the North Slope on an existing gravel bed pad that can accommodate year-round operations is envisioned. Such an effort would again require engaging private sector and international partners.