Comparison of Texas shale plays – geologic characteristics and implications for

production of the Eagle Ford/Tuscaloosa Marine Shale, Haynesville/Bossier,

Wolfcamp/Bone Springs, and Barnett/Woodford plays.

Texas shale plays are some of the most prolific oil and gas producers in the world and have been

compared to many shale plays around the world. However, a comparative study of geologic

characteristics of the Texas shale plays has not been presented. This study compares the carbonate-dominated shales of the Eagle Ford and Haynesville formations, the silica dominated shales of the Barnett/Woodford and Wolfcamp/Bone Springs formations and the argillaceous dominated shales of the Tuscaloosa Marine Shale. Knowing the impact of the shales’ depositional environments on background mineralogy is important because it has a direct influence on reservoir quality (porosity, permeability, brittleness) of the shales.

The carbonate-dominated Eagle Ford and Haynesville/Bossier shales exhibit pore networks that are dominated by interparticle pores between calcite grains, intraparticle pores within skeletal grains, and pores in organic matter. These units were bordered by carbonate platforms that sourced carbonate debris into the basins. The Barnett/Woodford and Wolfcamp/Bone Springs shales were deposited in deep-water environments influenced by siliceous skeletal grains and invariable shedding of carbonate and silica-dominated turbidites into the basin. These shales are dominated by interparticle and intraparticle pores between silica and clay grains, but the majority of the porosity in these shales is related to organic-matter nanopores. Although, the Tuscaloosa Marine Shale is of the same age as the carbonate-dominated Eagle Ford Shale, the depositional setting was mainly siliciclastic and argillaceous sediments shed into the basin by Lower Cretaceous deltas. This shale contains interparticle porosity between clay and organic-matter pores. Knowledge of the depositional setting and history, source and sediment transport, and environmental conditions in a shale play provides insight into pore networks, porosity and permeability, and brittleness of the rocks forming the shale play and these insights can be applied to other shale plays.

Ursula Hammes, Ph.D.

Hammes Energy & Consultants

Austin, TX

www.hammesenergyconsultants.com

ursula@hammesenergyconsultants.com

Education:

Diploma (MSc), University of Erlangen, Germany, 1987

PhD, University of Colorado at Boulder, 1992

Dr. Ursula Hammes is currently President of Hammes Energy & Consultants and Adjunct Professor

at the Department of Geological Sciences, Texas A&M University, teaching and assessing various

shale oil/gas systems. Dr. Hammes has 25+ years of experience in the oil and gas industry and

academia in Europe and USA in positions ranging from exploration, development, research and

management. She has provided advanced consulting in shale-gas/oil and carbonate systems and

has taught industry short courses and in-house training courses for universities and oil

companies.

Dr. Hammes obtained her Diploma at the University of Erlangen, Germany, and her Ph.D. at the

University of Colorado at Boulder. Her graduate studies specialized in carbonate depositional

environments, sequence stratigraphy, carbonate diagenesis, and rock-water interactions. Her

background is diverse ranging from exploration, exploitation and business development for

Anadarko Petroleum, consulting for Marathon Oil, Equinor, and various other independent

oil/gas companies, conducting research in Texas and the Gulf of Mexico as Research Scientist

and Principal Investigator of $3+ million projects for the State of Texas Advanced Resource

Recovery project and leading research and advising students at the University of Potsdam,

Germany, Texas A&M University, and Bureau of Economic Geology at the University of Texas at

Austin. Before her career and oil and gas she also worked for an environmental firm, IT

Corporation (now Shaw Environmental), as geoscientist.

Dr. Hammes is past-president of the Energy and Minerals Division (EMD) of AAPG, served as

president of the Gulf Coast Section of SEPM (GCSSEPM), serves as senior associate editor for

the AAPG Bulletin, and has been chair and moderator of many AAPG conventions and sessions.

She has served as shale liquids and gas committee chair for EMD. Her research interests range

from tight shale, sandstone, and carbonate analyses to clastic and carbonate sequence

stratigraphy, reservoir characterization, and sedimentology. She has published extensively in

recognized sedimentologic and petroleum industry professional journals.