June 8, 2016, This is the second-largest assessment of potential shale & tight gas resources that the USGS has ever conducted.
Note: in early 2013, a Mancos Shale study by the Colorado Mesa University stratigraphically calibrated the Upper Mancos, Prairie Canyon, Niobrara and Lower Mancos.
The Mancos Shale in the Piceance Basin of Colorado contains an estimated mean of 66 trillion cubic feet of shale natural gas, 74 million barrels of shale oil and 45 million barrels of natural gas liquids, according to an updated assessment by the U.S. Geological Survey. This estimate is for undiscovered, technically recoverable resources.
The previous USGS assessment of the Mancos Shale in the Piceance Basin was completed in 2003 as part of a comprehensive assessment of the greater Uinta-Piceance Province, and estimated 1.6 trillion cubic feet of shale natural gas.
“We reassessed the Mancos Shale in the Piceance Basin as part of a broader effort to reassess priority onshore U.S. continuous oil and gas accumulations,” said USGS scientist Sarah Hawkins, lead author of the assessment. “In the last decade, new drilling in the Mancos Shale provided additional geologic data and required a revision of our previous assessment of technically recoverable, undiscovered oil and gas.”
The Mancos Shale is a significant potential source of natural gas. For comparison, the assessed mean resources in the Mancos Shale of the Piceance Basin are the second-largest assessment of potential continuous gas resources that the USGS has ever conducted.
Since the last USGS assessment, more than 2,000 wells were drilled and completed in one or more intervals within the Mancos Shale of the Piceance Basin. In addition, the USGS Energy Resources Program drilled a research well in the southern Piceance Basin that provided significant new geologic and geochemical data that were used to refine the 2003 assessment.
The Mancos Shale is more than 4000 feet thick in the Piceance Basin, and contains intervals that act as the source rock for shale gas and oil, meaning that the petroleum was generated in the formation. Some of the oil and gas migrated out of the source rock and into tight (low permeability) reservoirs within the Mancos, as well as into conventional reservoirs both above and below the formation. Oil and gas also remained in continuous shale gas and shale oil reservoirs within the Mancos.