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Roberto Henry Ebelt

Shale gas é o gás obtido através do fracionamento do xisto.

Fracking é nome que os americanos deram ao cracking of the shale (= fracionamento do xisto).

PENNSYLVANIA, the site of America’s first oil wells (=well também pode funcionar como substantivo e então o seu significado é poço) back in the 1850s, is now home to the world’s second-largest gas field after South Pars, on the border (=fronteira) between Qatar and Iran. At the turn of the millennium, America’s conventional gas fields were in decline. The country was preparing to become a significant importer: around $100 billion was invested in LNG (=Liquid Natural Gas) import terminals that may now be redundant. Shale gas was known to geologists but had never been worth extracting (=nunca tinha valido a pena extrair). As recently as 2000 hardly any of it was coming out of the ground (= até 2000 dificilmente algum [gás de xisto] estava sendo extraído do solo)

Observação: a palavra GAS, em inglês, é enganadora. Para compreender o seu significado correto, no texto que estamos lendo, é necessário prestar atenção ao contexto, pois ela tanto pode significar gasolina como gás.

Now shale (=xisto) contributes a third of America’s gas supplies. By 2035, the country’s share of total supplies (which may by then have risen to 820 billion cubic meters a year) could be nearly half. The rise has been helped along by a variety of factors, such as the liberalization of access to existing pipelines (=oleodutos) by third parties that started in the 1970s, a deep and liquid gas market that allowed the risks of drilling to be hedged, ready access to capital, America’s home-grown oil industry and the entrepreneurial zip (=energia) that provided the men and equipment. But the biggest difference was down to the efforts of one man: George Mitchell, the boss of an oil-service company, who saw the potential for improving a known technology, fracking, to get at the gas. Big oil and gas companies were interested in shale gas but could not make the breakthrough (=avanço) in fracking to get the gas to flow. Mr Mitchell spent ten years and $6m to crack (=resolver) the problem (surely the best-spent development money in the history of gas). Everyone, he said, told him he was just wasting his time and money.

The technology is in use in the Marcellus, Haynesville, Barnett, Utica and other shale beds (see map below), to startling =surpreendente) effect. It is also being used for shale oil, which can be extracted from some shale beds in the same way as gas. Some wells also render valuable natural-gas liquids (NGLs) such as butane and propane along with the gas. Oily parts of the Eagle Ford are giving up the black stuff in big quantities. The Bakken shale in North Dakota, a state with little else to boast about (=para se gabar), now contributes around half a million barrels a day (b/d) of oil. Some reckon that in a few years the oily shale beds might produce as much as 3m b/d, around a third of America’s current (=atual, atuais) imports.

The cost of getting at the gas has come tumbling down as techniques have become more efficient. Drilling (to drill = perfurar) multiple wells from a single pad (=platform), up to six at a time, has made operations cheaper. Three-dimensional seismic imaging has made it easier to find sweet spots where gas might flow in large quantities. Horizontal drilling sections have got longer. Break-even costs(=custos que pagam o empreendimento) have plummeted (=cairam bruscamente).

Para ler mais sobre esse assunto, que, diga-se de passagem, não tem nada a ver com a história muito mal contada do sub-salt oil que, dizem, encontra-se abaixo de uma camada de sal que, por sua vez, encontra-se abaixo de uma lâmina d'água superior a 5.000 metros, siga os seguintes links:

• An unconventional bonanza
• Landscape with well
• Sorting frack from fiction
• A world of plenty
• Careful what you wish for
• A liquid market
• A better mix
• Oil prices
• Financial markets
• Commodity markets
• Fossil fuels
• Energy industry

Para terminar, saibam que a quantidade máxima de etanol, misturada na gasolina americana, é de 10%. As perspectivas são de que essa percentagem suba até 15% no futuro próximo, pois eles já produzem mais etanol do que o Brasil. Pode? Além disso, eles estão investindo muito na produção de metanol.

Agora uma pergunta:
Se alguém souber como é que um internal combustion engine do tipo flex, pode funcionar satisfatoriamente, com pure ethanol e uma compression ratio de 11:1, por favor, me informe. Pergunto porque tal compression ratio (11:1) é a utilizada em motores movidos a gasolina. Até hoje não consegui entender como a eletrônica consegue tal milagre, pois a compression ratio de um motor a etanol é de quase 18:1. Em minha ignorância não compreendo como um sistema eletrônico possa mudar a estrutura de um bloco de motor fundido em ferro ou alumínio de uma hora para outra.

O artigo completo sobre SHALE GAS & FRACKING se encontra em inglês no endereço http://www.economist.com/node/21558459

Have an excellent weekend.