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The Explorers 2024: A global first at the top of the globe
ASRC Energy launches first long-term test of methane hydrates production
Eric Lidji for Petroleum News
As this issue of The Explorers was going to print, ASRC Energy Services was about six months into long-term test of a North Slope methane hydrates well ' a global first.
The subsidiary of the Alaska Native corporation for the North Slope began the test in late October 2023 on state lease ADL 47450 in the western end of the Prudhoe Bay unit, working on behalf of a consortium including both American and Japanese entities.
ASRC Energy completed three wells on the lease in late 2022 and early 2023 ' Hydrate O2, Hydrate P1, and Hydrate P2 ' from the Kuparuk State 7-11-12 pad at Prudhoe Bay, some 20 miles northwest of Deadhorse. The company had previously completed the Hydrate O1 well in late 2018 and early 2019, but the project was delayed the following spring with the arrival of first restrictions associated with the coronavirus pandemic.
The drilling and testing program is being called the International Hydrates Testing Project, an acknowledgment of the global partnership behind the undertaking. ASRC Energy Services Alaska Inc. is under contract with the National Energy Technology Laboratory of the United States Department of Energy as well as the Japan Oil, Gas and Metals National Corp. to conduct methane hydrate research at the site.
A separate contract with Prudhoe Bay operator Hilcorp North Slope LLC allowed ASRC Energy to drill and complete the three recent wells at the unit to produce methane from gas hydrate zones for specific purposes, to collect data and to install surface facilities. It also required ASRC Energy to remove its infrastructure at the end of the project.
The earlier well came during the operatorship of BP Exploration (Alaska) Inc.
The Hilcorp contract prohibited ASRC Energy from drilling 'to any depth or location that may encounter or otherwise interfere with or impact any interval producing oil or gas within the (Prudhoe Bay unit) by the (Prudhoe Bay unit) working interest owners.'
According to previous project descriptions, one well would be produced through a series of depressurization tests. As much as 1.7 million standard cubic feet per day of gas would be produced during the test, about the size of a mid-range Cook Inlet natural gas field.
Any production will be used at the facility, with additional supplies coming from an unnamed North Slope producer, according to the state. 'In emergency conditions, excess produced gas will be flared. In no circumstances will produced gas be shipped off site.'
According to a timeline included in state filings, the production test would last around seven months. If correct, the test would be completed some time in May or June 2024.
History In the never-ending effort to pull more hydrocarbons out of the North Slope, methane hydrates have captured the imagination of geologists and drillers in the 21st century.
Once considered a nuisance, they are now seen as a huge resource. Free the methane from its hydrate 'cage,' and it contains some 160-180 times its volume in free gas.
There have been numerous methane hydrate research projects around the world over the past 25 years. Alaska has been a global center for much of this research thanks to the prevalence of the resource within close proximity to existing development infrastructure.
While those efforts have yielded much valuable data, they were all relatively short. The current test is the first time development theories are being tested over long periods of time, crucial for understanding how the resource responds to changes in field pressure.
In a conventional reservoir, underground pressure pushes hydrocarbons to the surface through a wellbore. As this pressure declines over time, it must be boosted artificially.
With methane hydrates, relatively high pressures and low temperatures actually impact the structure of the resource, and therefore production can alter the nature of the resource. If that process can be better understood and controlled, the hydrates can be unlocked.
Some believe this process is already underway at the East Barrow gas field, which has surpassed original estimates for gas in place without major declines in reservoir pressure.
A preliminary study of the field in the early 2000s suggested that the reservoir might exist at least partially within the stability zone required for producing hydrates. (An alternate theory credits the extended production to water flowing into the reservoir and bolstering production, but low water production at the field might suggest otherwise.)
Resource size The reward for cracking the code is huge. According to the Office of Fossil Energy, 'Gas hydrate deposits are found wherever methane occurs in the presence of water under elevated pressures and at relatively low temperatures, such as beneath permafrost or in shallow sediments along deepwater continental margins. Once assumed to be rare, gas hydrates are now thought to occur in vast volumes and to include 250,000-700,000 trillion cubic feet of methane and the formation thickness can be several hundred meters thick.'
One cubic meter of hydrates can release 164 cubic meters of natural gas. And according to the U.S. Geological Survey, the North Slope could hold some 53.8 trillion cubic feet of natural gas contained within hydrates ' relative to Prudhoe Bay or Point Thomson in size.
Alongside the work at Barrow in the mid-2000s, the U.S. Department of Energy convened a public-private coalition to further study methane hydrates on the North Slope.
Working with BP Exploration (Alaska), ASRC Energy Services, Ryder Scott Co., the U.S. Geological Survey, the University of Alaska Fairbanks and the University of Arizona, the DOE completed preliminary geologic and economic modeling in 2004.
BP Exploration planned to drill a stratigraphic test well at the Mount Elbert prospect at the Milne Point unit in early 2007. The team used seismic data to make predictions about the prospect and then drilled to get some confirmation of those predictions. 'As it turned out our predictions were very correct,' the DOE's methane hydrates technology manager Ray Boswell said at the time. The Mount Elbert well confirmed hydrates in two zones.
The project also involved some technical milestones. It developed a new technique for recovering core samples before the methane disassociated from the surrounding water. It also included the first open-hole extended duration pressure test of a gas hydrate reservoir, allowing the team to verify some of the conclusions of its prior modeling.
After a period of extended analysis, the DOE and BP Exploration announced plans in early 2009 to conduct a long-term gas hydrates production test for data collection.
Around that time, the DOE joined a third North Slope methane hydrates project led by ConocoPhillips Alaska to develop methane hydrates using carbon dioxide injections.
ConocoPhillips spud the Ignik Sikumi No. 1 well in early 2011 from a site adjacent to L-pad at the Prudhoe Bay unit. The Japan Oil, Gas and Metals National Corp. joined the project the following winter, during the injection and production phase of the project.
A collection of technical papers about the program can be found online at https://pubs.acs.org/doi/full/10.1021/acs.energyfuels.2c02106?ref=EFHydratesAlaska
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