ALBERT

Description: Shale-gas resource plays can be distinguished by gas type and system characteristics. The Newark East gas field, located in the Fort Worth Basin, Texas, is defined by thermogenic gas production from low-porosity and low-permeability Barnett Shale. The Barnett Shale gas system, a self-contained source-reservoir system, has generated large amounts of gas in the key productive areas because of various characteristics and processes, including (1) excellent original organic richness and generation potential; (2) primary and secondary cracking of kerogen and retained oil, respectively; (3) retention of oil for cracking to gas by adsorption; (4) porosity resulting from organic matter decomposition; and (5) brittle mineralogical composition. The calculated total gas in place (GIP) based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf/section (5.78 × 109 m3/1.73 × 104 m3). We estimate that the Barnett Shale has a total generation potential of about 609 bbl of oil equivalent/ac-ft or the equivalent of 3657 mcf/ac-ft (84.0 m3/m3). Assuming a thickness of 350 ft (107 m) and only sufficient hydrogen for partial cracking of retained oil to gas, a total generation potential of 820 bcf/section is estimated. Of this potential, approximately 60% was expelled, and the balance was retained for secondary cracking of oil to gas, if sufficient thermal maturity was reached. Gas storage capacity of the Barnett Shale at typical reservoir pressure, volume, and temperature conditions and 6% porosity shows a maximum storage capacity of 540 mcf/ac-ft or 159 scf/ton. Dan Jarvie is an analytical and interpretive organic geochemist. He has worked on conventional hydrocarbon systems and unconventional shale-oil and shale-gas hydrocarbon systems, including the Barnett Shale since 1989. He earned a B.S. degree from the University of Notre Dame and was mentored in geochemistry by Wallace Dow and Don Baker of Rice University. He is president of Humble Geochemical Services. Ronald Hill specializes in petroleum geochemistry and has more than 12 years of professional experience, including those with ExxonMobil and Chevron. Currently, he is a research geologist for the U.S. Geological Survey. His interests include investigation of shale-gas resources and the processes that control petroleum generation. He holds geology degrees from Michigan State University (B.S. degree) and the University of California, Los Angeles (Ph.D.), and a geochemistry degree from the Colorado School of Mines (M.S. degree). Tim Ruble is a petroleum geochemist with Humble Geochemical Services and is currently involved in studies focused on the assessment of shale-gas resources. He has had a diverse professional career that has included periods with the Commonwealth Scientific and Industrial Research Organization in Australia, Mobil Oil, and the U.S. Geological Survey. He has published on a variety of geochemical topics, including lacustrine petroleum systems, oil-bearing fluid inclusions, native bitumens, biomarker analyses, and hydrocarbon generation kinetics. Tim earned his B.S. degree in chemistry from Truman State University and his M.S. degree and his Ph.D. in geology from the University of Oklahoma. Richard Pollastro received an M.A. degree in geological science from the State University of New York at Buffalo in 1977. He joined the U.S. Geological Survey in 1978 and has served as a province geologist on the national and world energy assessment projects. His recent accomplishments include petroleum system analysis and resource assessment of the Bend arch–Fort Worth Basin, with particular focus on Barnett Shale, South Florida Basin, and the Arabian Peninsula.