The discovery of vast amounts of shale gas in the United States has already had a big impact on the country’s energy use—prompting a shift away from coal and helping to reduce greenhouse gas emissions (see “A Drop in U.S. CO2 Emissions” and “King Natural Gas”). By some estimates, China has even more shale gas. But it will be difficult for China to access these resources, which are bound up in shale rock, without significant advances in extraction technologies—including the use of powerful computer simulations of the physical properties of shale deposits.
China has set itself an ambitious goal of obtaining 60 billion cubic meters of shale gas by 2020, enough to produce about 6 percent of all of its energy, up from almost none today. But China faces a number of challenges in developing these resources. Most of the gas is found in arid areas, and the current approach for freeing the gas—hydraulic fracturing—requires a lot of water. What’s more, the geology is different in China than in the United States, which could make hydraulic fracturing more difficult.
“China has a lot of natural gas in shale,” says Julio Friedmann, chief energy technologist at the Lawrence Livermore National Laboratory. “But we don’t know how much of that gas they can produce, and what’s necessary to get it out of the ground; we don’t know how much it will cost to produce.”
New fracking techniques could help. For example, ways to reduce water consumption are being developed in the United States, where some of the shale gas is in dry areas, such as parts of Texas. New water treatment methods are making it possible to recycle more water (see “Can Fracking Be Cleaned Up?”). In the future, extremely fine particles that flow “like ball bearings” might replace much of the water used now, says Franz-Josef Ulm, a civil and environmental engineering professor at MIT. The particles could be pumped into a shale deposit under pressure to fracture the shale, along with just a small amount of liquid.
Addressing the differences in geology will likely require a much better understanding of the specifics of each formation—such as temperatures, pressures, mineral composition, and the way organic materials interact with the rock. “Whenever you talk about gas shale, every area is completely different. Each gas play has its own features, depending on its geologic history,” Ulm says. For example, shale rock in China tends to contain considerably more clay than the shale in much of the U.S., and clay deforms rather than fractures under pressure. The amount of clay in some shale deposits in China may be small enough that the rock can be fractured simply by increasing the hydraulic pressure. Where that doesn’t work, new techniques may be required.
Ulm is developing computer simulations that can predict the behavior of shale rock from the interactions of different minerals and organic materials in a deposit. The simulations suggest that injecting solvents into a formation to dissolve specific organic materials that act as glue could reduce the amount of pressure needed for fracking, Ulm says. But such an option should be a last resort because the chemicals could be dangerous, he notes.
Ulm’s simulations also suggest potentially easier ways to improve the efficiency of shale gas extraction. Computer simulations could give natural gas companies a better sense of where within a shale deposit to frack by modeling how differences in the mineral makeup and organic makeup of the deposit will affect the fracturing process. Injecting carbon dioxide or heating up the formation with steam—as is done now with tar sands in Canada—could also help.
But even if such techniques prove successful, it is unlikely that producing and using shale gas will have a major impact on greenhouse gas emissions in China, as least in the next several years, Friedmann says. China lacks a pipeline infrastructure to carry natural gas from western China, where most shale gas is, to the population centers in the east to be burned in power plants instead of coal. Instead it’s likely to be used first for chemical production. Friedmann estimates that even so, emissions from coal consumption are likely to be reduced by 100 to 150 million tons a year, since coal is now used to produce some chemicals in China. But China is estimated to produce over 9,000 million tons of greenhouse gases a year, and that number is expected to grow substantially.
“If shale gas production scales up in China, we’ll get some offsets of produced coal. But it’s not a panacea for [addressing] climate [change],” he says.
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