File:Schematic cross-section of general types of oil and gas resources and the orientations of production wells used in hydraulic fracturing.jpg

Summary
https://commons.wikimedia.org/wiki/File:Schematic_cross-section_of_general_types_of_oil_and_gas_resources_and_the_orientations_of_production_wells_used_in_hydraulic_fracturing.jpg Description English: Shown are conceptual illustrations of types of oil and gas wells. A vertical well is producing from a conventional oil and gas deposit (right). In this case, a gray confining layer serves to “trap” oil (green) or gas (red). Also shown are wells producing from unconventional formations: a vertical coalbed methane well (second from right); a horizontal well producing from a shale formation (center); and a well producing from a tight sand formation (left). Note: Figure not to scale. Modified from USGS (2002) and Newell (2011). Date	June 2015 Source	U.S. EPA. Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/047, 2015. Author	unknown US Government employee