While Australians are aware of the expansion of conventional gas output in the Timor Sea, the most interesting development globa

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问题     While Australians are aware of the expansion of conventional gas output in the Timor Sea, the most interesting development globally is the role taken by "unconventional gas", a technical term to describe coal-seam gas, shale gas and tight sands gas.
    In Australia, major new coal-seam gas developments are being brought on stream in the Hunter Valley in New South Wales, and the Surat Basin in Queensland, but there are no developments here of shale gas or tight sands gas.
    In the United States, due to technological developments over the past 20 years, about half of America’s natural gas now comes from these sources, rather than the conventional sources which include natural gas platforms in the Gulf of Mexico.
    The switch towards unconventional gas is the result of higher gas prices and improved technology. Only in the United States, which has both massive consumption of energy and dwindling sources of conventional oil and gas, has unconventional gas been developed to any extent.
    Similar developments can be expected in other countries as the technology developed in the United States is applied elsewhere.
    Over the past decade, production from all three unconventional gas sources in the US has increased dramatically. The largest increase has been in tight gas, while the largest percentage increase has come from shale gas, where production has risen 300 percent. Driven by record well-drilling, proven reserves have also risen dramatically, so that unconventional gas now makes up more than half of the United States’ proved reserves of natural gas.
    Significant probable and possible reserves, as well as a large undiscovered resource base, underscore the proved reserves.
    Speaking at the recent World Gas Conference in Buenos Aires, Argentina, the president of the American Gas Association, Thomas E. Skains, referred to the dramatic impact of the growth of unconventional gas on the US energy industry, and more broadly, its economy.
    He said: "Perhaps never in its history has the US domestic natural gas industry experienced more changes than now, and this is just the beginning."
    "The largest change affecting the US market is an increasingly home-grown supply portfolio, led by unconventional onshore shale gas. The abundance of American natural gas resources is a fundamental change—a paradigm shift—in conventional wisdom."
    Other technologies are also being developed in the United States. Conventional oil wells have a low recovery rate, because of the high cost of recovering "stranded" oil, which remains in the well as a result of a decline in oil pressure. Enhanced recovery techniques are being developed to improve oil recovery from conventional wells.
    The increased production of unconventional gas has had an unexpected consequence for global natural gas prices.
    Analysts expect the full impact of the unconventional gas revolution has yet to be felt, especially as its potential outside the United States has not even begun.
    "It will probably take three or four years to get one’s arms around the scale of it," said Daniel Yergin, one of the world’s leading energy commentators.
    A recent study by Cambridge Energy Resource Associates, which Yergin heads, concluded that unconventional gas reserves could be as much as 16 quadrillion cubic feet, or roughly double current proved reserves.
    Predictions that the world is running out of oil and gas—popularised by Dr Paul Ehrlich in the 1970s and repeated endlessly in the media by David Suzuki and the Greens—are utterly wrong.
                                                From News Weekly, October 31, 2009
According to the passage, which of the following statements is true?

选项 A、All kinds of the unconventional gas are being much developed in Australia.
B、Most of America’s natural gas now comes from the conventional sources.
C、The development of the unconventional gas results in higher gas prices.
D、Only in the US has the unconventional gas been developed to any extent.

答案D

解析 本题为概括题。根据第二段“…but there are no developments here of shale gas or tight sands gas”可知A错误;根据第三段“about half of America’s natural gas now comes from these sources,rather than the conventional sources”可知B错误;根据第四段“The switch towards unconventional gas is the result of higher gas prices…”可知C因果相反;根据第四段“Only in the United States…has unconventional gas been developed to any extent”可知D正确。
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