The Piceance Basin is getting so big. Roughly 13 years and 2,000 drilled wells since the last assessment of its resources, a U.S. Geological Survey (USGS) report says the basin has grown into the second-largest U.S. unconventional gas play yet assessed.

Colorado’s Piceance—specifically the Mancos Shale—is now estimated to contain 66 trillion cubic feet (Tcf) of undiscovered technically recoverable shale gas, about 40x more than initial estimates of 1.65 Tcf.

The increase in resources is consistent with other reassessments by the USGS. In 2013, a new study of the Marcellus Shale found it contains about 84 Tcf of undiscovered technically recoverable natural gas, far outstripping its 2002 assessment that the Marcellus held 2 Tcf of gas.

The previous USGS assessment of the Mancos Shale was completed in 2003 as part of a comprehensive assessment of the greater Uinta-Piceance Province. Since the last USGS assessment, more than 2,000 wells were drilled and completed in one or more intervals within the Mancos Shale.

“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 past 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 USGS Energy Resources Program also 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 4,000 ft thick and contains intervals that act as the source rock for shale gas and oil, meaning that the petroleum was generated in the formation, the USGS said.

“Some of the oil and gas migrated out of the source rock and into tight reservoirs within the Mancos, as well as into conventional reservoirs both above and below the formation,” the USGS report said. “Oil and gas also remained in continuous shale gas and shale oil reservoirs within the Mancos.”

Hydraulic fracturing has unlocked shale oil and gas in the younger, shallower parts of the Mancos as well as in older, deeper intervals.U.S. Rep. Scott Tipton, R-Colo., said the USGS assessment is a tremendous find for western Colorado’s economic security and also for the nation’s energy security.

Tipton, echoing other elected officials, said the gas resources should induce the Federal Energy Regulatory Commission (FERC) to review its decision denying a permit for the Jordon Cove LNG Terminal. A permit for Veresen Inc. regarding that project was rejected in March.

“Utilizing this resource can become a reality by getting commonsense projects like the Jordan Cove Pipeline off the ground, increasing U.S. natural gas exports and establishing a true all-of-the-above domestic energy policy through responsible production,” Tipton said.

Tipton said he is working with colleagues from the Colorado, Wyoming and Utah congressional delegations to pressure the Obama administration into allowing the Jordan Cove Pipeline to move forward. Once completed, the pipeline would transport natural gas produced in western Colorado and other states to the West Coast for export.

The Western Energy Alliance said that federal policies have continued to make production of oil and natural gas challenging, particularly on federal lands.

In the past 12 months, the Alliance said it has responded to 49,226 pages of federal regulations between the Environmental Protection Agency (EPA) and the U.S. Department of the Interior.

Kathleen Sgamma, vice president of government and public affairs at the Alliance, said much of the Piceance Basin is federal land managed by the Bureau of Land Management (BLM).

“Getting approval from the BLM to drill is often more difficult than getting private landowners to agree,” Sgamma said. “I hope with this reassessment the government understands that indeed the Mancos Shale is an important formation that should be developed responsibly.”

Darren Barbee can be reached at dbarbee@hartenergy.com.

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