The Barnett Shale may have lost some of its allure as producers chased other unconventional prizes, but an updated federal assessment indicates the venerable North Texas play holds nearly double the amount of undiscovered natural gas, liquids and oil resources than estimated in 2003.

The U.S. Geological Survey (USGS) on Thursday issued its first assessment of the North Texas play in 12 years. Scientists now estimate mean volumes of undiscovered, technically recoverable resourcesof 53 Tcf of gas, 172 million bbl of shale oil and 176 million bbl of natural gas liquids (NGL). The estimate updates conventional and unconventional reservoir potential within the the Bend Arch-Fort Worth Basin Province.

As the unconventional revolution was getting started, led by the Barnett, the play was estimated to hold a mean of 26.2 Tcf of undiscovered gas and 1.0 billion bbl of undiscovered NGLs. Potential oil resources were not quantitatively assessed at that time.

“We decided to reassess the Barnett Shale following the successful introduction of horizontal drilling and hydraulic fracturing, setting the stage for the current shale gas boom,” said USGS scientist Kristen Marra, who led the assessment. “In addition, the newly revised assessment incorporates estimates for both gas and oil resources within the Barnett.”

The 2003 assessment had relied on potential reserves that could be captured through vertical drilling only. The USGS Barnett assessment was undertaken as part of a nationwide project assessing domestic petroleum basins using standardized methodology and protocol.

In the past dozen years, more than 16,000 horizontal wells have been drilled into the play, which all together have produced an estimated 15 Tcf of gas and 59 million bbl of oil, USGS noted.

Since the advent of unconventional drilling, the USGS has undertaken new assessments and updated older ones. In 2011 it estimated that the Marcellus Shale contained a mean of 84 Tcf of undiscovered gas (see Shale Daily,Aug. 29, 2011). Scientists in 2013 also updated their assessment of the Williston Basin’s Bakken Shale in North Dakota (see Shale Daily,May 1, 2013). The Bakken and Three Forks formation in in Montana, North Dakota and South Dakota were found to contain a combined estimated 6.7 Tcf of gas, 7.4 billion bbl of oil and 530 million bbl of NGLs.