The U.S. Geological Survey (USGS) has deemed the Eagle Ford abundant in both oil and gas, estimating undiscovered, technically recoverable resources in the region at about 8.5 billion barrels (Bbbl) of oil, 66 trillion cubic feet (Tcf) of gas and 1.9 Bbbl of NGL.

In a report released June 22, the USGS said the Eagle Ford contains one of the most prolific continuous accumulations of oil and gas in the U.S. The USGS described the Eagle Ford’s composition as mostly mudstone and calcareous mudstone (marl) with organic-rich intervals, deposited in outer shelf and upper slope environments during the Cenomanian–Turonian ages.

“This assessment is a bit different than previous ones because it ranks in the top five of assessments we’ve done of continuous resources for both oil and gas,” USGS scientist Kate Whidden, lead author for the assessment, said in a statement about the report. “Usually, formations produce primarily oil or gas, but the Eagle Ford is rich in both.”

The report, which covers only unconventional resources, is the federal agency’s first that alone assesses the so-called Eagle Ford Group and associated Cenomanian-Turonian strata onshore. The Eagle Ford spans from the Texas-Mexico border across parts of south an east Texas to the Texas-Louisiana border.

The results, which included evaluation of six continuous assessment units, put the region among the top five largest continuous resources for oil and gas in the U.S.

“This assessment ranks second behind the Wolfcamp in Texas for largest continuous oil assessment we’ve ever done and ties with Mancos in Colorado for third largest continuous natural gas we’ve ever done,” Alex Demas, spokesperson for the USGS, told Hart Energy in an email.

With 304 Tcf, the combined Haynesville-Bossier region leads and is followed by Marcellus/Appalachian Basin with 84 Tcf. The Mancos-Niobrara Piceance Basin and Eagle Ford each have about 66 Tcf.

Source: USGS


“Texas continues to remain in the forefront of our nation’s energy supply chain with remarkable increases in production and reserves due to the revolutionary unconventional techniques used to release previously unrecoverable resources,” Dr. Jim Reilly, USGS director, said in the statement. He later added, “We regularly reassess potential resources, as we have for the Eagle Ford in this report, in response to changes in estimated ultimate recovery as new techniques or productive horizons are pioneered.”

Like in other places known for unconventional oil and gas development, hydraulic fracturing, horizontal drilling and more efficient rigs are having an impact in the Eagle Ford. Operators here are optimizing completions, adjusting spacing and lateral lengths, looking to get the most from their wells.

The presence of oil and gas in the Eagle Ford Group has long been known, the USGS said, but production really got underway in East Texas in 2008.

The latest drilling productivity report from the U.S. Energy Information Administration shows Eagle Ford oil production is expected to hit about 1.36 MMbbl/d in June, increasing to just under 1.4 MMbbl/d in July—trailing only the Permian. Likewise, gas production is also expected to rise, going from an expected 6.8 Tcf/d in June to 6.9 Tcf/d in July—following the Appalachia, Permian and Haynesville regions.

The Eagle Ford’s ample resources may come as a positive for oil and gas producers looking to add reserves and grow production closer to the Gulf Coast refinery scene in Texas as infrastructure woes continue.

The USGS defines undiscovered resources as “those that are estimated to exist based on geologic knowledge and statistical analysis of known resources, while technically recoverable resources are those that can be produced using currently available technology and industry practices.”

“Whether or not it is profitable to produce these resources has not been evaluated,” the USGS said.

Velda Addison can be reached at