|
Hydrate testing on NS
DOE confirms participation in an international project to evaluate production
Alan Bailey for Petroleum News
The U.S. Department of Energy has confirmed that it is participating in an international project to evaluate the production of natural gas from gas hydrate deposits under the North Slope. The objective is to assess the practicalities of the continuous production of methane from the deposits.
“The success of this test will move us closer to characterizing, evaluating and confirming the potential for gas hydrates production on the Alaska North Slope, in the Gulf of Mexico and globally,” said Brad Crabtree, assistant secretary for fossil energy and carbon management. “We look forward to continue working with our partners to conduct world-class gas hydrates research.”
DOE is partnering on the project with the U.S. Geological Survey; Japan’s Ministry of Economy, Trade and Industry; the Japan Oil, Gas and Metals National Corp., referred to as JOGMEC; and ASRC Energy Services, the project operator. Japan has a particular interest in the project because of major subsea gas hydrate deposits offshore the island nation. As previously reported in Petroleum News, the Alaska Department of Natural Resources approved the project in early August.
Highly concentrated natural gas Gas hydrate, also referred to as methane hydrate, is a solid in which molecules of methane, the primary component of natural gas, are concentrated inside a lattice of water molecules. Huge quantities of the material, which remains stable within a certain range of relatively high pressures and low temperatures, are known to exist around the base of the permafrost under the North Slope. Gas can be released from hydrates through some combination of elevating the temperature or reducing the pressure of the hydrate resource. Although there have been demonstrations of short-term hydrate production, no one has yet conducted a sustained, long-term production test.
Alaska’s North Slope is considered a particularly suitable venue for the testing, given the presence of large quantities of methane hydrate, onshore, in a region with an extensive oil and gas development and production infrastructure.
DOE says that the primary objective of its gas hydrate research program is “to advance the scientific understanding of gas hydrates as they occur in nature, so their resource potential and role in climate change can be fully understood.”
Initial well completed early 2019 In January 2019 the partnership completed an initial test well from an existing gravel pad in the western part of the Prudhoe Bay unit. At that time, BP operated the drilling project. The well penetrated two highly saturated hydrate-bearing reservoirs, and there is a third hydrate bearing sand zone in the same area. The deeper of the penetrated reservoirs appeared particularly suitable for production testing, while the shallower reservoir could provide additional research opportunities.
The expectation was to drill two additional wells. One of the these wells would be used for the sustained testing of gas production from the hydrates, while the other well, together with the well completed in 2019, would be used for collecting data relating to the hydrate production. Drilling permit applications subsequently indicated that the additional drilling was planned for the winter of 2021-22, with production testing taking place in 2021 or 2022. ASRC Energy Services also applied to Alaska’s Division of Mining, Land and Water for the use of gravel pads across the region between the Colville and Canning Rivers for subsurface temperature monitoring in connection with the methane hydrate test program.
However, the anticipated drilling did not take place, presumably as a consequence of a hiatus in North Slope drilling as a result of the COVID pandemic.
Three wells now planned DOE now says that the project partners will drill three wells in 2022 - a DOE funded geo-data well and two production test wells funded by JOGMEC. DOE will carry out the testing. The testing will be conducted through a drilling agreement between ASRC Energy Services and Hilcorp Alaska, the Prudhoe Bay unit operator. The geo-data well will be used to collect subsurface sediment samples before being converted into a second monitoring well.
DOE says that the objective of the testing is to determine the response to production of the hydrate reservoir over a long enough time to effectively evaluate how gas hydrates release gas in response to reservoir depressurization. The agency says that the North Slope research site provides a unique opportunity to conduct testing over many months.
Previous test wells There have been two previous gas hydrate test wells drilled on the North Slope. In 2011 and 2012 the Ignik Sikumi well shed light on the potential use of injected carbon dioxide as a means of producing natural gas from methane hydrate, while also demonstrating that producing gas by depressuring the deposits may work more easily than previously thought. And in 2007 BP, the DOE and the U.S. Geological Survey drilled the Mount Elbert methane hydrate stratigraphic test well at Milne Point - tests in this well demonstrated the possibility of depressuring the hydrates and thus releasing methane by extracting free water from the hydrate reservoir.
In 2002 a methane hydrate test well in northwestern Canada attempted methane production through the application of hot water to a hydrate reservoir but found this technique to be ineffective. However, another test demonstrated that the hydrates could be disassociated through depressurization without the artificial application of heat. A further test in 2008 using this same well succeeded in producing about 13,000 cubic meters of gas over a six-day period using depressurization.
More recently, two methane hydrate production tests in the Eastern Nankai Trough, offshore Japan, demonstrated the stable production of natural gas and water for several days through the drawdown of pressure in the hydrates.
|
