human
I've been hearing a lot about fracking lately. What is it and is it safe?
assistant
Fracking is the process of drilling into rock layers to extract oil or gas. It involves injecting a high-pressure mixture of water, sand and chemicals into the rock layer at a depth of several thousand feet. The pressure causes cracks in the rock which allows the gas or oil to flow more easily out of the rock. Fracking can be done horizontally or vertically. Horizontal fracking is typically used for extracting natural gas from shale formations. Vertical fracking is used for extracting oil from tight sands or shale reservoirs.