--> --> Updated U.S. Geological Survey Petroleum Resource Assessment of Continuous and Conventional Reservoirs of the San Juan Basin, New Mexico and Colorado

AAPG Rocky Mountain Section Meeting

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Updated U.S. Geological Survey Petroleum Resource Assessment of Continuous and Conventional Reservoirs of the San Juan Basin, New Mexico and Colorado

Abstract

The San Juan Basin covers more than 14,000 square miles across northwestern New Mexico and southwestern Colorado and has been a prolific gas producing basin since the 1920s. Production of gas, oil, and natural gas liquids is from Jurassic to Tertiary sandtone, shale, and coal reservoirs. In 2002, the U.S. Geological Survey (USGS) completed a comprehensive assessment of undiscovered, technically recoverable petroleum resources within continuous (unconventional) and conventional reservoirs in the San Juan Basin and estimated means of 50.6 trillion cubic feet of gas, 19.1 million barrels of oil, and 148.4 million barrels of natural gas liquids. The basin stratigraphy was divided into the following four total petroleum systems (TPS), which includes the extent of source rocks, reservoir rocks, and migration pathways for various units: 1) Fruitland TPS, 2) Mancos-Menefee Composite TPS, 3) Lewis Shale TPS, and 4) Todilto TPS. Within these TPSs, a total of 14 assessment units, which represent the mappable volume of rock that is quantitatively assessed, were defined. The primary units assessed include the Fruitland Formation, Pictured Cliffs Sandstone, Lewis Shale, Mesaverde Group, Gallup Sandstone, Mancos Shale, Dakota Sandstone, and Entrada Sandstone. Exploration and production in the San Juan Basin have slowed in recent years; however, since 2002, additional drilling has been completed primarily in the Fruitland Formation, Mesaverde Group, Dakota and Pictured Cliffs Sandstones. The USGS will conduct a new assessment of reservoirs within the San Juan Basin, which will benefit from analyzing more recent well and production data, as well as evolving technology trends (e.g., vertical, directional, and horizontal drilling) within these historically productive reservoirs.