Jun
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Lots More Natural Gas – A Lot More
June 1, 2009 | 9 Comments
The U.S. Department of Energy (DOE), the U.S. Geological Survey (USGS), U.S. Minerals Management Service (MMS) and a group of U.S. and international energy industry companies under the management of Chevron have completed the first ever drilling project with the goal to collect geologic data on gas-hydrate-bearing sand reservoirs in the Gulf of Mexico.
Results, stunning, on just one test operation.
USGS Scientist Timothy Collett said, “We have also found gas hydrate in a range of settings, including sand reservoirs, thick sequences of fracture-filling gas hydrates in shales, and potential partially saturated gas hydrates in younger systems. These sites should provide a wealth of opportunities for further study and data collection that should provide significant advances in understanding the nature and development of gas hydrate systems.”
Brenda Pierce, the U.S. Geological Survey Energy Program Coordinator adds, “This is an exciting discovery because for the first time in the U.S. Gulf of Mexico, we were able to predict hydrate accumulations before drilling, and we discovered thick, gas hydrate-saturated sands that actually represent energy targets.”
The important thing to note is that the prediction led to discoveries. That point must not be underestimated. We know there is a lot down there, so knowing where to look is the next step with finding it as expected being a huge time and money saver.
To refresh, gas hydrates, are substances comprised of natural gas and water, thought to exist in great abundance in nature and with the potential to be a significant new energy source to meet future energy needs. It may even be larger than anyone has predicted so far.
Now we know that the U.S. Gulf of Mexico contains very thick and concentrated gas-hydrate-bearing reservoir rocks, which have the potential to produce gas “using current technology.” That’s a new comment within the quotes from the USGS press release. I will get in touch with my Chevron folks to see if they’re backing that comment up, or cautioning more research will be needed and ask for a comment.
Now for some of the more neck twisting, surprising and set one back in the chair numbers. NETL’s Dr. Ray Boswell is saying in the background materials, “This (gas hydrate as an energy resource) potential forms the foundation of the Office of Fossil Energy’s Methane Hydrate R&D Program, which is focused on expanding future energy options by developing the information and technology required for eventual production of natural gas from hydrate.” During the expedition, gas hydrate was found at saturations ranging from 50 percent to more than 90 percent in high-quality sands. The deposits were also found in close accordance with the project’s pre-drill predictions, providing increased confidence in our gas hydrate exploration and appraisal technologies.
Now I take saturation to mean, well, saturation. Commenting at 90% has to be in my view outside of the structure’s sands, shales and rocks. Perhaps that 90% is the share of the gas hydrate to water ratio. It’s not clear and needs cleared up.
What is missing is the permeability and porosity numbers that reveal the voids within the structures that can be filled with the water and gas hydrate mix and the freedom by which the methane from gas hydrates when unfrozen could be moved. Those are the numbers that will give meaning.
Another point in the background is the project featured a number of technical advances, including the use of an advanced suite of logging-while-drilling tools that provided unprecedented three-dimensional images of hydrate-bearing sediments. In addition, the wells drilled at Walker Ridge, approximately 3,500 feet below the seafloor, were more than 1,000 feet deeper than any previous gas hydrate research well.
Gas Hydrate Downhole Exploration Tool. Click image for more.
This bodes well for the future of natural gas supplies. Somewhere, Chevron perhaps, the dill site was identified and when tested with the bit and the instruments proved exciting to say the least.
Others were also involved. Schlumberger provided the initial appraisals of the targets. Borehole Research Group at Lamont-Doherty Earth Observatory of Columbia University is in on it too. I’ve looked for the full list of the group Chevron led with the easy result here.
That confirms the objective of the 21-day expedition that gas hydrate can and does occur at high saturations within reservoir-quality sands in the Gulf of Mexico with highly saturated hydrate-bearing sands discovered in at least in two of three sites drilled. Dr. Collett said, “In addition, we have found gas hydrate in a range of settings, including sand reservoirs, thick sequences of fracture-filling gas hydrates in shales, and potential partially saturated gas hydrates in younger systems. These sites provide a wealth of opportunities for further study and data collection that will enable significant advances in understanding the nature and development of gas hydrate systems.”
The project also featured a number of technical advances, including the use of an advanced suite of logging-while-drilling tools that provided unprecedented three-dimensional images of hydrate-bearing sediments. The wells sited at Walker Ridge, drilled to approximately 3,500 feet below the seafloor, were more than 1,000 feet deeper than any previous gas hydrate research well.
It all looks very good. The puzzle is in the opening line of the USGS Newsroom asserting current technology could lead to production. Just what technology is an intensely interesting answer that may or may not be coming. It could be just a journalist’s slip from the reality or something more noteworthy. We’ll see.
Other than the current technology surprise, the news is quite encouraging. Natural gas is a great product wherever it comes from with all that hydrogen tied up to a single carbon atom in the molecule. Plus methane has great potential as a fuel from giant electrical generation to cars and on to very small fuel cells. Great stuff and a great deal more is good news for consumers.
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The USGS released a study on technically recoverable resources from Alaska hydrates late in 2008. It indicated 85 tcf technically recoverable with current technologies. The rub here is that we do not need to invent anything new to produce gas from hydrates. We do need to know how to combine the existing pieces to maximize production rate. And even at that point, it is not clear how economic that rate might be at what prices. So a lot left to do.
Since these are sand reservoirs, it is safe to assume that the saturation estimates are percent of hydrate in pore space. These numbers are similar to what has been reported previously for sand reservoirs (mostly in the Arctic).
By the way, the technology is simple depressurization (drill borehole-evacuate borehole-draw mobile fluids to the borehole-pressure drop spreads throughout formation-hydrate dissociates-gas follows pressure-gradient to well, etc.). Current numerical simulations of obtainable rates by that method are all over the board, but the April 2008 Japanese-Canadian test got encouraging results using that method. Occassional thermal stimulation to clear ice from near-borehole may be required in some temperature settings…
Use the current generation of super high efficiency catalysts and fischer tropsch to convert a small portion of this gas into clean desiel. Then we have a clean transportation fuel that is produced in this country.
With the current Administration pushing the dollar over a cliff – imported oil is about to get real, real expensive.
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