Sergie, Mohammed Aly. Hydraulic Fracturing (Fracking). Oct 2013. Council on Foreign Relations.

“Geologists have known about vast reservoirs of natural gas and oil trapped in shale formations across the United States for decades, but extraction techniques weren’t available and the resources remained untapped. Shale didn’t factor into most serious analyses of U.S. energy prospects until the combination of two old technologies—horizontal drilling and hydraulic fracturing, known colloquially as fracking—was perfected. A drilling renaissance over the past five years has transformed the United States into a leading natural gas producer and potential energy exporter, reversing a decades-long trend of increasing reliance on foreign sources of oil and gas. Shale production helped reduce net imports of energy by one-third between 2011 and 2013, according to the U.S. Energy Information Administration, heralding a new era of U.S. energy security with broad implications for global markets and international relations.”