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Dr. Terry Engelder
Department of Geosciences, The Pennsylvania State University (USA)
Terry Engelder, a leading authority on the recent Marcellus gas shale play, holds degrees from Penn State B.S. (’68), Yale M.S. (’72) and Texas A&M, Ph.D. (’73). He is currently a Professor of Geosciences at Penn State and has previously served on the staffs of the US Geological Survey, Texaco, and Columbia University. Short-term academic appointments include those of Visiting Professor at Graz University in Austria and Visiting Professor at the University of Perugia in Italy. Other academic distinctions include a Fulbright Senior Fellowship in Australia, Penn State’s Wilson Distinguished Teaching Award, membership in a US earth science delegation to visit the Soviet Union immediately following Nixon-Brezhnev détente, and the singular honor of helping Walter Alvarez collect the samples that led to the famous theory for dinosaur extinction by large meteorite impact. He has written 150 research papers, many focused on Appalachia, and a book, the research monograph "Stress Regimes in the Lithosphere". In the international arena, he has worked on exploration and production problems with companies including Saudi Aramco, Royal Dutch Shell, Total, Agip, and Petrobras. In 2011 he was named to the Foreign Policy Magazine’s list of Top 100 Global Thinkers.
The extraction of natural gas from shale is now routine using massive slickwater hydraulic fractures. Along with its obvious economic advantages, this extraction technique comes with a number of well publicized risks, foremost of which is the migration of methane in the subsurface. Subsurface migration is a consequence of drilling into exhumed gas fields such as the Appalachian Basin where the areal extent of the Marcellus makes this gas reservoir one of the world’s largest. During thermal maturation of the Marcellus between 300 Ma and 265 Ma gas was distributed throughout the Catskill Delta complex by natural hydraulic fractures (NHF). Migration of reducing fluids within redbeds of the delta complex accompanied NHF. Reduction halos allow the mapping of these pathways. While NHF was gas-driven as indicated by a cyclic plume pattern on fracture surfaces, high permeability NHF allowed the modern distribution of gas in these exhumed gas fields.