Ummm... it’s in the water. So how does drilling cause “ground surface collapse”?
What a dip-wad! (the author)
Sometimes peoples leg-bone just ain’t connected to their brain-bone!
Much of it is in Arctic permafrost.
Accomplishments
Task 1 – Characterization and Assessment of Natural Gas Hydrates in Permafrost Environments
This task addressed the critical issues associated with potential production of gas hydrates (and associated free gas) in the Prudhoe-Kuparuk area of the Alaska North Slope. The primary focus was to assess the geophysical characteristics of in situ natural gas hydrates and to support U.S. DOE-funded extended gas hydrate production tests of the Eileen and Tarn gas-hydrate/free-gas accumulations.
USGS worked directly with BPXA and their contractors to design and implement the North Slope of Alaska Mt. Elbert 1 Gas Hydrate Test Well, which was spudded on February 3, 2007.
The USGS coordinated the efforts of BPXA and the U.S. DOE at Milne Point, Alaska, and participated in wellsite wireline coring, well logging, and sampling/pressure testing using a modular formation dynamics tester (MDT) during the 22-day drilling program. The project cored to a depth of 760 meters, logged to a depth of 914 meters, and tested for gas hydrate response at four depth intervals using MDT. From the coring program, there was 85% recovery, with approximately 250 samples selected for laboratory analyses and 11 gas-hydrate samples preserved in either liquid nitrogen or pressure vessels for analysis.
The major scientific achievement at this site is that two high-saturation gas hydrate-bearing intervals were identified, as predicted from pre-drilling geological and geophysical analysis using prospecting methods developed by the USGS. The two units were an upper 14-m thick gas hydrate-bearing reservoir of sandstone (unit “D”) and a lower 16 m thick unit, also a reservoir. Both units had gas hydrate saturations of 60–75%. Two technological firsts were also achieved: (1) conducting wireline retrievable coring in the relatively unconsolidated sub-permafrost sediments in the North Slope and (2) conducting open-hole MDT testing within gas hydrate-bearing intervals. For more information see the BP Exploration Alaska project, “Alaska North Slope Gas Hydrate Reservoir Characterization” (DE-FC26-01NT41332).
The wireline logging produced an outstanding dataset of permafrost and gas hydrate properties. The open-hole MDT testing also produced an outstanding dataset of gas hydrate response during testing. Research is now being conducted to analyze the physical formation properties of the Mt. Elbert samples and to compare the detailed drilling results with pre-drilling models so that the models can be refined and improved. A Mt. Elbert data set was also developed as a case study to be utilized in the DOE-funded “International Effort to Compare Methane Hydrate Reservoir Simulators”.
Using calibration data from the Mt. Elbert gas hydrate stratigraphic test well, the USGS has reprocessed and inverted 3-D seismic data to further refine the limits of the Milne Point Units C and D gas hydrate occurrences. This effort has resulted in the generation of an updated time-depth model, a structural map, a hydrate saturation map, and hydrate reservoir thickness maps for Mt. Elbert prospect. The USGS continues to participate in project meetings focused on detailed planning for the future Alaska North Slope long-term gas hydrate production testing program under a new IA, DE-FE0002911. USGS efforts also included developing and editing papers prepared for the North Slope of Alaska Mount Elbert Gas Hydrate Stratigraphic Test Well Scientific Results Volume, to be published as a special edition of Marine and Petroleum Geology. USGS scientists made a major commitment to this special volume by authoring and/or coauthoring over half of the 25 papers included in this publication.
USGS scientists provided technical and scientific support for the ConocoPhillips (CP) project by contributing to the development of the coring and logging research plan for the upcoming “CO2 gas hydrate production test well.” The USGS contributions included providing required geologic data from our historical work in northern Alaska, and providing expert knowledge on well logging, conventional coring, pressure coring, seismic characterization, sediment physical properties, organic geochemistry, and process modeling.
With the Bureau of Land Management, the USGS processed and analyzed 3-D seismic grids and related 2-D seismic and well data from the National Petroleum Reserve-Alaska (NPRA) in order to identify gas hydrate prospects. This research focused on gathering existing geologic and geophysical data to construct a new gas hydrate stability map for the eastern portion of the NPRA. The research resulted in a new North Slope Alaska gas stability field map as interpreted from the USGS “Borehole Temperature Logs from Arctic Alaska”. These data have been released on the following web site, http://esp.cr.usgs.gov/data/bht/alaska/ [external site].
In a related effort, in collaboration with the Bureau of Land Management, the USGS completed the first assessment of undiscovered technically recoverable gas hydrate resources beneath the North Slope of Alaska. For the Northern Alaska Gas Hydrate Total Petroleum System, the USGS estimated that the total undiscovered natural gas resources in gas hydrate are about 85 trillion cubic feet (TCF). More information can be found at http://pubs.usgs.gov/fs/2008/3073/ [external site].
Ummm... it’s in the water. So how does drilling cause “ground surface collapse”?
What a dip-wad! (the author)
Sometimes peoples leg-bone just ain’t connected to their brain-bone!
The author might have written it better. But the ground, (Ocean Floor), has more of a chance of collapsing with the weight of the water on top as the Hydrates are removed.
Which has its own measure of risk, imagine a Methane Ice breakthrough rising to the surface of the surrounding water. The potential there for methane poisoning of the water is pretty high and the release of the sublimating ‘ice’ into methane gas into the atmosphere is there too.
Once all of these risks and potential hazards are worked around there is a lot of energy available as well as ‘feed-stock’ for various industries that can use it to produce other goods and materials.