Barnett Shale Resources Twice as Large than Previously Thought

A new assessment now estimates the size of the Barnett shale play’s undiscovered, technically recoverable resources to be twice as large as originally thought.

According to a recent U.S. Geological Survey Assessment (USGS), the Barnett shale contains estimated mean volumes of 53 trillion cubic feet (Tcf) of shale natural gas, 172 million barrels of shale oil and 176 million barrels of natural gas liquids.

The last time USGS released an assessment of the undiscovered, technically recoverable resources of the Barnett shale was in 2003. That assessment estimated a mean of 26.2 Tcf of undiscovered gas and 1 billion barrels of undiscovered gas liquids within the Barnett. The 2003 assessment of the Barnett shale was released as part of an assessment of conventional and unconventional reservoirs of the Bend Arch-Fort Worth Basin province. The shale’s potential oil resources were not quantitatively assessed at that time.

USGS decided to reassess the Barnett after horizontal drilling and hydraulic fracturing were successfully introduced, setting the stage for the current shale gas boom, said USGS scientist Kristen Marra, who led the assessment, in a Dec. 17 press statement. The substantial increase in the Barnett’s potential resources is largely due to the oil and gas industry’s switch to primarily horizontal drilling within the Barnett, paired with hydraulic fracturing.

The 2003 assessment relied solely on vertical drilling. Since 2003, over 16,000 horizontal wells have been drilled into the formation. The horizontal wells have helped produced over 15 Tcf of gas and 59 million barrels of oil in the Barnett.

The Barnett shale stretches from Dallas, Texas west and south, covering 5,000 square miles and at least 18 counties, according to the Texas Railroad Commission (TRC) website. The late George P. Mitchell – considered the father of shale gas because of the techniques he developed to exploit shale – initially targeted the Barnett shale formation with these techniques. Production grew from 216 million cubic feet per day in 2000 to a peak of approximately 5.7 billion cubic feet per day (Bcf/d) in 2012, according to the TRC. Since 2012, production has declined; production from January to September 2015 total 4.3 Bcf/d.

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