50.1 MB (3.5 MB compressed)
5117 x 3425 pixels
43.4 x 29.0 cm ⏐ 17.1 x 11.4 in (300dpi)
BILL CUNNINGHAM / US GEOLOGICAL SURVEY / SCIENCE PHOTO LIBRARY BILL CUNNINGHAM / US GEOLOGICAL SURVEY / SCIENCE PHOTO LIBRARY
Fracking well heads. Four well heads at a drill pad being used in a hydraulic fracturing operation. Fracking or hydraulic fracturing is a drilling technique used to extract gas from shale deposits. A mixture of sand, chemicals and water is pumped under high pressure from the surface to underground horizontal wells. The pressure forms fissures (fractures) in the shale. The sand keeps the fissures open, allowing gas to flow into the well and rise to the surface. This is part of exploratory drilling being carried out to assess the potential of the Fayetteville Shale in Arkansas, USA.
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