Animation of Hydraulic Fracturing (fracking)

Video animation shows how Marathon Oil extracts oil and gas from shale

Shale reservoirs consist of oil and/or natural gas trapped within microscopic pores in the rock layers. During the fracking process, a liquid mixture, which is generally made up of 90 percent water, 9.5 percent sand and 0.5 percent chemicals such as gels and surfactants, is pumped into the shale formation under high pressure to create small fractures allowing the oil and natural gas to flow more easily into the well. The sand remains underground and prevents the fractures from closing, allowing the oil and natural gas to continue flowing into the well.