BP Drills Alaska North Slope Gas Hydrate Test Well to Assess Potential Energy Resource
BP Exploration (Alaska) has successfully drilled a research well on the North Slope in partnership with the U.S. Department of Energy and the U.S. Geological Survey to collect samples and gather knowledge about gas hydrate, a potential long-term unconventional gas energy resource.
The stratigraphic test well enabled BP and the Department of Energy to gather core, log, reservoir performance and fluid data from an ice pad location at Milne Point. The drilling began Feb 3. Field teams began pulling hydrate core samples on Feb. 10. Extensive well logging and wireline formation testing was completed between Feb. 14-18.
"With this project, we have significantly increased our understanding of gas hydrate-bearing formations on the Alaska North Slope," said Scott Digert, BP resource manager and the project's technical adviser. "The results also illustrate the value of collaborative research," he said.
This test well is part of the ongoing research partnership between BP and the Department of Energy, which began in 2002.
Known deposits of methane hydrate in Alaska and other parts of the world are enormous. However, the challenge is finding the technology to unlock the energy, to separate the natural gas from the solid gas-water-ice "clathrate" in which it occurs.
The DOE has identified gas hydrate as a research target and funded the estimated $4.6 million cost of drilling the Milne test well. BP contributed seismic data, staffing and program oversight. The on-site coring and data team included scientists from the USGS, DOE, Oregon State University and an observer from India's hydrate program.
Drilling crews and research team members collected about 430 feet of core samples. The cylindrical core segments, about 3 inches in diameter, were initially subsampled and analyzed on site due to the time-and temperature-dependent data requirements. They will be shipped to Anchorage for temporary storage before being distributed to gas hydrate researchers around the country. Subsequent data collection and analysis will continue for several months. A report of findings will be released thereafter.
This well provided a stratigraphic test of interpreted gas hydrate accumulations from Milne seismic and well data. Core, wireline logs, and wireline down hole testing will help assess gas hydrate-bearing sediment, shallow reservoirs, and fluid properties.
Location: ice pad 1.4 miles south of the Milne B-pad, reached by an ice road. The Milne Point oilfield is northwest of the Prudhoe Bay oil field, and is owned and operated by BP.
Depth: 3,000 feet
Target: Gas hydrate within the Sagavanirktok formation in the Mt. Elbert prospect accumulation, identified by seismic, well, and reservoir modeling studies during in Phases 1-2 of this research program.
Key data acquired: 430 feet of hydrate core, Logging While Drilling & extensive wireline open-hole logs, and Modular Dynamic Tester sampling for fluid and reservoir flow-properties data.
Unique technology: Drilling mud chillers and the Reed Hycalog (Corion) wireline-deployed coring system, both of which have been used in Canada and in the lower-48 but not in Alaska.
This is a joint effort of the DOE's National Energy Technology Laboratory (NETL), the USGS, BP Exploration (Alaska) Inc., Arctic Slope Regional Corporation, the universities of Alaska and Arizona, and others.
The project recorded a number of firsts, including the first significant gas hydrate-bearing core in Alaska, and the first delineation of seismically-defined gas hydrate prospect in Alaska.
Key on-site participants: The coring & data team included scientists from the USGS, DOE, BP, ASRC Energy Services, Oregon State University, and an observer from India's gas hydrate program.
Methane hydrate is a solid substance that forms by combining gas and water within the pore space of sediments within a defined pressure/temperature stability window. Those conditions occur within and beneath permafrost in onshore areas and beneath the seafloor in offshore regions.
On the North Slope, gas hydrate has been found in numerous locations during drilling for oil and gas. At Milne it is located in the Sagavanirktok formation, in dispersed deposits beneath the permafrost, about 1800 to 2500 feet below the surface.
The gas is contained within a solid "clathrate" structure which compresses 160-180 unit volumes of gas into a single volume of gas hydrate.
What happens next? Will there be a hydrates production test? BP's current focus is on the successful completion of this stratigraphic test well, and subsequent analysis of the data. The direction of potential future program efforts will be determined with DOE following those evaluations.
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