Unconventional Oil and Gas Resources in Northeast Mexico, 2014

Using a geology-based method, the U.S. Geological Survey estimated that the Sabinas, Burgos and Tampico-Misantla Basin provinces of northeast Mexico hold means of 0.78 billion barrels of unconventional oil, 23.5 trillion cubic feet of unconventional gas and 0.88 billion barrels of natural gas liquids.

The Sabinas, Burgos and Tampico-Misantla Basin provinces assessed in this study.

What was assessed

With the U.S. Department of State, the USGS assessed the potential for unconventional resources — shale gas, shale oil, tight gas, tight oil and coalbed gas — in three provinces. The Veracruz Basin was not assessed quantitatively for lack of reservoir information. Mexico's undiscovered conventional oil and gas had been assessed in 2012.

The method is based on well performance and allows for geologic variability within each reservoir. Outside the United States, the USGS assesses shale-oil or shale-gas reservoirs only where:

1. total organic carbon (TOC) exceeds 2 percent by weight;
2. the rock is in the right thermal maturity window to generate oil or gas;
3. there are more than 15 metres of organic-rich shale;
4. the organic matter is Type I or II.

Areas outside these limits are unlikely to hold significant resources without major technological advances or higher prices. The criteria can shrink the resource area a lot compared with maps drawn at 1 percent TOC: in the Tampico-Misantla Basin, the part of the Pimienta Shale above 2 percent TOC is only about 21 percent of the thermally mature shale.

A key step was a formal USGS–PEMEX (Petróleos Mexicanos) workshop on unconventional resources in Mexico City in June 2012, which examined the geology and exploration results in each shale-oil and shale-gas assessment unit. PEMEX supplied several maps of geologic data critical to the assessment; combined, they defined the areas in the three basins that met the criteria.

The Boquillas/Eagle Ford Formation exposed on the south bank of Langtry Creek in Pump Canyon, Val Verde County, Texas. Photograph by Michael Lewan, August 19, 2010.

Results

The USGS assessed 11 assessment units in 3 geologic provinces.

• Oil: about 82 percent is in the Tampico-Misantla Basin — 55 percent (426 million barrels) in the Agua Nueva Shale Oil unit and 27 percent (212 million) in the Pimienta Shale Oil unit. The Burgos Basin's Agua Nueva Shale Oil unit holds the other 18 percent (138 million).
• Gas: about 66 percent (15,591 billion cubic feet) is in the Burgos Basin, 25 percent (5,822) in the Sabinas Basin and 9 percent (2,061) in the Tampico-Misantla Basin.

MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Estimates are fully risked; for gas units, all liquids are counted as NGL.

Studies of the geologic models and methods behind the assessment were in progress; results are on the USGS Energy Resources Program site.

Sources

• Schenk, C.J., Charpentier, R.R., Klett, T.R., Tennyson, M.E., Gaswirth, S.B., Brownfield, M.E., Pawlewicz, M.J., and Weaver, J.N., 2014, Assessment of unconventional oil and gas resources in northeast Mexico, 2014: U.S. Geological Survey Fact Sheet 2014–3047. https://pubs.usgs.gov/publication/fs20143047 — the map, photograph and tables come from its PDF.
• Rewritten in hubnx's own words.