In essence, shale operators drill down as per normal, but when they reach a petroleum-rich rock strata they take a sharp turn, drilling horizontally along the entire layer. Then they pump water and sand at high pressure into the formation. Since liquids do not compress, the rock cracks apart from within, freeing untold trillions of tiny pockets of oil and natural gas that would otherwise be far too small to harvest with conventional drilling. The sand suspended in the frack fluid props the cracks open, while the now-freed oil provides reverse pressure that pushes the water back up the pipe.
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