A Geochemical Context for Stray Gas Investigations in the N. Appalachian Basin
Tuesday, April 25, 2017: 8:15 a.m.
Fred Baldassare, P.G.
,
Echelon Applied Geoscience Consulting, Murrysville, PA
Mark McCaffrey, Ph.D
,
Geosciences, Weatherford Laboratories, Dallas, TX
John Harper, Ph.D
,
Natural History, Carnegie Museum of Natural History, Pittsburgh, PA
More than 2,300 gas and water samples were analyzed in the present study for (1) molecular composition, (2) stable carbon and hydrogen isotope compositions of methane and (3) stable carbon isotope composition of ethane. The samples are from Neogene to Middle Devonian-age strata in a five-county study area in northeastern Pennsylvania. Gas and water samples were collected from (1) 234 gas wells during Mudgas Logging (MGL) programs for wells being drilled to the Marcellus Shale Formation, and (2) 67 private water supply wells during baseline groundwater water-quality testing programs. Regional and local geologic conditions were evaluated from core analyses and published studies.
Evaluation of this geochemical database reveals that microbial, mixed microbial/thermogenic, and thermogenic gases occur in some shallow aquifer systems, and that the gas occurrences pre-date Marcellus Formation drilling activity. The isotope data reveal that thermogenic gases in the Neogene and Upper Devonian strata are typically distinct from gases from deeper Middle Devonian strata (including the Marcellus Fm.).
Defining a specific source for stray natural gas requires the investigation and synthesis of several data types at the site-specific level. Molecular and isotope geochemistry provide evidence of gas origin and evidence of secondary processes that may have affected the gases. Such data provide focus for investigations where the potential sources for stray gas include multiple naturally occurring and anthropogenic gases. Additional investigation to delineate migration pathways and the mechanism of migration are necessary to further constrain and identify specific stray gas source(s).
Fred Baldassare, P.G., Echelon Applied Geoscience Consulting, Murrysville, PA
Fred Baldassare is Principal Geoscientist and owner of Echelon Applied Geosciences Consulting. He has more than 20 years of experience investigating incidents of stray gas migration. He previously served as the statewide consultant for the Pennsylvania Department of Environmental Protection for investigating and characterizing sources of stray carbon dioxide and methane. Baldassare helped pioneer the application and advancement of isotope geochemistry to identify the origin of stray and natural gases in the Appalachian Basin. He has authored and co-authored numerous professional papers for peer-reviewed publications on the application of isotope geochemistry.
Mark McCaffrey, Ph.D, Geosciences, Weatherford Laboratories, Dallas, TX
Dr. McCaffrey received his B.A. (1985) from Harvard University, magna cum laude with highest honors in geological sciences, and his Ph.D. (1990) in chemical oceanography (in the area of organic geochemistry) from the Massachusetts Institute of Technology/ Woods Hole Oceanographic Institution Joint Program. Mark spent 10 years at Chevron and Arco as a petroleum geochemist, then founded OilTracers LLC, a firm specializing in applications of petroleum geochemistry.
He is author of numerous articles on the application of geochemistry to petroleum exploration, reservoir management, oil biodegradation, and paleoenvironmental reconstruction. As an Expert Witness in gas fingerprinting, he has testified (i) in Mississippi State Court, (ii) in Ohio Federal Court, (iii) before the Oklahoma Corporation Commission, and (iv) before the Railroad Commission of Texas. Mark is a PetroSkills Instructor in the area of Oil and Gas Geochemistry, and has taught classes in: Bahrain, Brazil, Colombia, Egypt, England, India, Indonesia, Japan, Jordan, Kuwait, The Netherlands, Mozambique, Saudi Arabia, Tunisia, United Arab Emirates, and the USA.
John Harper, Ph.D, Natural History, Carnegie Museum of Natural History, Pittsburgh, PA
John is currently Research Associate at the Carnegie Museum of Natural History and previously served as manager of Pennsylvania Topographic & Geological Survey, Oil & Gas Division. John has published numerous professional papers in peer reviewed journals on various aspects of petroleum geology in Pennsylvania.
