Reservas de gás natural

Fonte: The Economist

"Around 45% of the world’s recoverable natural-gas reserves are "unconventional", comprised mainly of shale gas, and also tight gas and coal-bed methane. The International Energy Agency (IEA) reckons global gas demand will increase by more than half between 2010 and 2035, and unconventional gas will make up 32% of the total supply, up from 14% today. While Russia and the Middle East hold the largest reserves of conventional gas, available sources of unconventional gas are spread across the world, and can be found in countries that are currently net importers, such as China and America. But the ease of accessibility will vary from well to well. Extracting shale gas (which is trapped between layers of shale rock) and tight gas (found in sandstone) involves bombarding the rock with water and chemicals, a technique known as "fracking". This is more expensive than the methods used to produce conventional gas. Costs differ between countries, too. China’s shale-gas and coal-bed methane industries are subsidised to the tune of 3 cents per cubic metre. Elsewhere there is less government support. France and Bulgaria have banned fracking for environmental reasons." The Economist