will include untested carbonates in the Central Basin Platform and potentially undiscovered plays in the Four Corners Platform. Mesozoic Fields Cretaceous-aged units account for the majority of gas and oil production in the San Juan Basin, i.e. nearly 250 of the >300 fields source Upper Cretaceous units. Major oil plays in the San Juan Basin target the Dakota Sandstone, the Gallup Sandstone, the Tocito Sandstone, and the El Vado Sandstone Member. The source rock for these units was the black, organic-rich marine shale of the stratigraphically lower Mancos Formation. Most of the oil fields described below are at or nearing depletion. Major gas plays in the San Juan Basin target the Dakota Sandstone, the Point Lookout Sandstone, and the Pictured Cliffs Sandstone. Plays consist of stratigraphic traps mostly concentrated in the Central Basin Platform. Oil Plays The Dakota Sandstone has nearly 40 oil fields throughout the Four Corners and Central Basin platforms, each having produced millions of barrels of oil. The Gallup Sandstone has about four oil fields on the Chaco Slope. Sandstones units have yielded tens of thousands to millions of barrels of oil. The Tocito Sandstone Lentil of the Mancos Shale has about 30 fields throughout the Four Corners and Central Basin platforms. The Tocito beds are the best Cretaceous reservoirs, having produced over 150 MBO (million barrels of oil) from a variety of structural and stratigraphic traps. The El Vado Sandstone Member of the Mancos Shale has produced from over nearly 40 fields mostly concentrated in the Central Basin Platform. This member alone has produced over 40 MBO. Gas Plays The Dakota Sandstone stores gas in offshore marine sandstones trapped by marine shales. Fracturing is required to source these units. The Pictured Cliffs Sandstone consists of regressive-marine deposits, where gas is stored in porous sandstones and trapped by mud- or siltstones. Production depends on natural fractures throughout unit. The Point Lookout Sandstone (see the Pictured Cliffs Sandstone above). Coal-bed Methane Plays The Fruitland Formation encompasses the San Juan Basin's gracious supply of methane-rich coal beds. Methane is found within thousands of coal beds throughout the Fruitland Formation. Similar to Paleozoic gas fields, there is a trend of increasing gas content (and thermal maturity) in a northeast direction. Cumulative production (2009) is 15.7 trillion cubic feet of gas, making this the largest coal-bed methane field in the world. Methane cloud In 2014 NASA researchers reported the discovery of