Timo wrote:If that's the case, what are the consequences/advantages to capturing the methane hyrdates underground, extracting them, using them for fuel, and ultimately releasing them into the atmospehere as exhaust, versus just letting them enter the atmosphere naturally. What's the better approach? Or worse approach?
Natural Gas and the EnvironmentEmissions from the Combustion of Natural Gas
Natural gas is the cleanest of all the fossil fuels, as evidenced in the Environmental Protection Agency’s data comparisons in the chart below, which is still current as of 2010. Composed primarily of methane, the main products of the combustion of natural gas are carbon dioxide and water vapor, the same compounds we exhale when we breathe. Coal and oil are composed of much more complex molecules, with a higher carbon ratio and higher nitrogen and sulfur contents. This means that when combusted, coal and oil release higher levels of harmful emissions, including a higher ratio of carbon emissions, nitrogen oxides (NOx), and sulfur dioxide (SO2). Coal and fuel oil also release ash particles into the environment, substances that do not burn but instead are carried into the atmosphere and contribute to pollution. The combustion of natural gas, on the other hand, releases very small amounts of sulfur dioxide and nitrogen oxides, virtually no ash or particulate matter, and lower levels of carbon dioxide, carbon monoxide, and other reactive hydrocarbons.
Greenhouse Gas Emissions
Because carbon dioxide makes up such a high proportion of U.S. greenhouse gas emissions, reducing carbon dioxide emissions can play a pivotal role in combating the greenhouse effect and global warming. The combustion of natural gas emits almost 30 percent less carbon dioxide than oil, and just under 45 percent less carbon dioxide than coal.
The study of natural gas hydrate systems in the field provides invaluable information on these widely variable and complex systems. Results from the field can be utilized for experimental and numerical studies which offer the potential to evaluate aspects of these systems on a variety of scales and through different methodologies. The research and technology requirements necessary to further advance the understanding of natural gas hydrate systems are significant. NETL Office of Research & Development’s (ORD) Natural Gas Hydrate Team conducts integrated research from the laboratory to the field, and from the molecular to the reservoir scale modeling, leveraging NETL-ORD’s strengths in geology, geochemistry, microbiology, and numerical simulation to improve understanding of these complex systems. The NETL-ORD’s field studies efforts are often aligned with other ORD R&D activities, key projects supported by the National Methane Hydrate R&D Program both domestically and internationally, and collaboration with external partners.
The primary goals of the DOE/NETL NGHFS project are:
Conduct field-based studies that advance our ability to predict, detect, characterize, and understand where, how, and what controls natural gas hydrate occurrences in relation to both resource and climate issues.
Analyze geologic, geochemical, and microbiologic data for indications of past and current changes to the stability of natural gas hydrate in marine settings;
Develop links between the U.S. Program and international R&D efforts through direct participation in international field programs & workshops;
Evaluate the potential role natural gas hydrates play in the global carbon cycle through analysis of modern and paleo-natural gas occurrences;
Provide expertise to domestic and international collaborators, focusing on activities such as pre-expedition/field site selection and evaluation, field analyses, and synthesis of samples and data collected in the field;
Supply geologic expertise to the efforts of DOE/NETL to advance numerical simulation and field-relevant experimental studies;
Work with the DOE’s domestic research partners, particularly those partners involved in major field operations in the Gulf of Mexico and Alaska, to ensure field test locations and plans are based on a full “gas hydrate systems” analyses.
Phase 1B Activities
With hydrate stability established in Phase 1A, Phase 1B will determine whether there is hydrate of sufficient thickness and reservoir quality updip of the free gas accumulations to support production. This will require an integrated review of all seismic, well, and production history data, building on previous studies of the field data. Of particular interest is
characterization of the updip pinchout of reservoir sands.
Assuming the results of the hydrate stability modeling and reservoir limits review are encouraging, a detailed reservoir characterization will be undertaken to support simulation of hydrate production methodologies and planning for a potential dedicated hydrate test well. A goal of reservoir simulation modeling will be to quantify the impact of hydrate dissociation
recharge of the producing gas fields. This work will aid in understanding
effectiveness of secondary production via depressurization of the associated free gas interval.
Based on the static and dynamic reservoir modeling, the optimum location of a dedicated hydrate well for sampling and production testing will be proposed. The well will be designed to fit the geologic, reservoir, and operational specifics required in the Barrow gas fields but will also leverage and expand on the findings of the Anadarko and Milne Point wells.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
In April, the U.S. Department of Energy and an international consortium of major oil and gas companies completed an unprecedented two-month proof-of-concept test in the North Slope of Alaska. The experiment was supposed to show that a steady flow of methane molecules could be extracted from a substance known as methane or gas hydrates submerged under the sea floor.
It worked and the world moved one step closer to tapping gas hydrates, the most abundant fossil fuel resource on Earth.
Gas hydrates consist of a crystalline substance in which methane molecules – the primary component of natural gas – are trapped in a lattice of water molecules.
“The energy content of methane in hydrate form is immense, possibly exceeding the combined energy content of all other known fossil fuels,” according to the Energy Department.
The US Department of Energy has selected 14 methane hydrate research projects in 11 states to receive up to $559 million of federal funding. The awards build on a successful, unprecedented test earlier this year where a steady flow of natural gas was safely extracted from methane hydrates on Alaska’s North Slope, DOE said.
DOE said the projects, which will be managed by the department’s National Energy Technology Laboratory, will advance understanding of the nature and occurrence of deepwater and arctic gas hydrates and their implications for future resource development and environmental performance.
The worldwide volume of natural gas held in methane hydrates is immense, but poorly known, according to NETL. Estimates range from 100,000 tcf to more than 1 million tcf, it said.
DOE said that prior research it has supported and outside studies have confirmed that the resource volume apparently is substantial, and amounts which can be explored for and produced using existing technologies are tremendous.
The 14 new projects will focus research on field programs for deepwater hydrate characterization, the response of hydrate systems to changing climates, and advances in the understanding of hydrate-bearing deposits, DOE said.
Expatriot wrote:This website would be so much more indicative of future events if Graeme were not allowed to post his/her constant stream of cornucopian fantasies.
Methane hydrates form at a specific range of low temperatures and high pressures. They occur in the Artic permafrost and along continental slopes, typically at water depths greater than 500 meters (1,640 feet). Once considered only a hindrance to conventional extraction, emerging technologies to tap methane hydrates mean they now have the potential to alter the global energy outlook. Estimates for total methane hydrate gas in place are rough, but range anywhere from 3,000 trillion cubic meters to more than 140,000 trillion cubic meters, the large range illustrating the uncertainty of the estimate. By comparison, combined global technically recoverable conventional natural and shale gas reserves total roughly 640 trillion cubic meters. (In 2011, global natural gas consumption stood at approximately 3.4 trillion cubic meters.)
Despite the promise of methane hydrates, the technology for their extraction is still under development, and potential risks have not been neutralized. These include the uncontrolled release of natural gas formerly trapped in ice, which could result in large amounts of the greenhouse gas methane entering the atmosphere. They also include the possibility of destabilizing the ocean floor, leading to underwater landslides and subsequently the possible sinking of drilling rigs.
Drilling likely will be required to access the natural gas in the hydrates. A number of drilling techniques could be used to destabilize the equilibrium of the hydrates and release natural gas. These include thermal injections, which involve increasing temperatures, often by injecting steam, to dissociate the gas. They also include depressurization, or reducing the pressure of the formation to release the gas. Finally, and perhaps most promising, is carbon dioxide injection. In this process, carbon dioxide essentially replaces the natural gas within the hydrate, allowing for the release of natural gas and the capture of carbon dioxide.
Research programs focused on methane hydrate detection and extraction can be found in numerous nations, including Japan, South Korea, India, China, Norway, the United Kingdom, Germany, the United States, Canada, Russia, New Zealand, Brazil and Chile. Much of the initial research has been highly collaborative, with the government and private companies from the United States playing a prominent role.
Many environmentalists are protesting the proposed Keystone XL Pipeline because it would help facilitate the delivery of oil from Canada’s oil sands and, they argue, increase carbon dioxide emissions. They may have more reason to worry about what’s happening in Alaska. The state’s Department of Natural Resources is teaming up with the U.S. Department of Energy to speed up production of natural gas from a resource—methane hydrate deposits–that’s far larger than the oil sands in Canada, and could in theory lead to far greater greenhouse gas emissions.
The only way to keep methane hydrates in the ground is for other sources of energy to make more economic sense. Doing that would require research to make sources like nuclear power cheaper, and likely taxing carbon emissions to make sources like methane more expensive.
Methane flowing from beneath the sea floor has buoyed Japan’s hopes for securing its own plentiful energy source. A pilot project 80 kilometres off the country’s shores produced tens of thousands of cubic metres of gas — and reams of useful data — before a clogged pump brought the project to an abrupt end last month.
Reservoirs of methane hydrates — icy deposits in which methane molecules are trapped in a lattice of water — are thought to hold more energy than all other fossil fuels combined. The problem is extracting the methane economically from the deposits, which lie beneath Arctic permafrost and seafloor sediments. But some scientists and policy‑ makers in energy-poor, coast-rich Japan hope that the reservoirs will become a crucial part of the country’s energy profile.
The test, run by the Tokyo-based state oil company Japan Oil, Gas and Metals National Corporation (JOGMEC), took place in waters 1 kilometre deep, where the research drilling ship Chikyu had bored through 270 metres of sediment to reach a 60-metre-thick methane hydrate reservoir. On 12 March, a pump reduced the pressure in the deposit, unlocking the gas from its icy cage. Gas started flowing up from the sea floor to a platform on the ship, where it produced a roaring flame.
The big question, and the one on which Japanese energy hopes depend, is whether the engineers can sustain the flow. They did — for a while. The methane flowed smoothly for six days, with the flow rate increasing as the pressure dropped, generating an average of 20,000 cubic metres a day — more than Yamamoto expected and ten times more than was produced by a well dug in Canadian permafrost in 2008 using the same depressurization method.
It is “a remarkable breakthrough”, says Scott Dallimore, a geoscientist at the Geological Survey of Canada in Sidney, British Columbia, who worked on the Canadian project with JOGMEC but was not involved in the Japanese offshore test. “The engineering challenge — to successfully undertake the test in a marine setting — was not insignificant. The flow rates are also very encouraging,” he says.
Ray Boswell, technology manager for the methane hydrates programme at the US Department of Energy’s National Energy Technology Laboratory in Morgantown, West Virginia, says that the test demonstrates that “what we have learned in the Arctic can be transferred to the marine environment, where the most significant resources are”. From his experience of extracting methane from hydrates in Alaska, the team would have had to overcome significant obstacles, he says: the loose, shifting sediment, unpredictable weather and the fact that the methane cools its surroundings as it dissociates from the ice slush, potentially creating new hydrates that could slow production or clog up the well.
Yamamoto says that his team took care to avoid such problems. To stop the formation of icy hydrates, the researchers carefully lowered the pressure in the reservoir, aiming to cap it at 3 megapascals (MPa) by the end of the two-week test to keep the methane in gas form. But on the sixth day, with the pressure down to 4.5 MPa, the pump clogged up with sand and the test had to stop. “It was a disappointment,” says Yamamoto. The team had used two sifting devices to try to prevent such a clog.
Yamamoto is confident that this and other obstacles can be overcome to create a steady supply of methane, but adds that improved extraction technologies and higher flow rates will be key to making the enterprise economically feasible. “We are 10 or 20 years behind shale, before they came up with fracking,” he says. Others are not sure it is worth it. Canada and the United States have drastically cut their methane hydrate efforts, largely because they have plentiful gas from shale. Projects in China, India and South Korea, however, remain active.
The team will now examine temperature, seismic and other data to learn how far the dissociation of hydrates spread and thus how much methane they might expect to extract from one well. Yamamoto plans to spend a year preparing the next test, which he hopes will run for a further 12 months and will use more sophisticated monitoring.
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