For the past 14 years, M&A has been pleased to award the Montgomery Prize to a student from the University of Arizona’s Hydrology & Water Resources Department. The recipient is selected by a panel of professionals based on oral presentations at the El Dia del Agua Symposium. The award, one of many given at this event, includes a $2,000 cash prize — a symbol of M&A’s ongoing commitment to promoting excellence in research and communication in the field of hydrology.
This year’s recipient of the El Dia del Agua Montgomery Prize is Melissa Schlegel, a Ph.D. candidate under the supervision of Dr. Jennifer McIntosh. Her research incorporates an important topic: energy generation. Read her abstract below.
Constraining the timing of microbial methane generation in an organic-rich shale using noble gases, Illinois Basin, USA
Melissa Schlegel, Zheng Zhou1, Jennifer McIntosh, Christopher Ballentine1
Department of Hydrology and Water Resources, The University of Arizona
Deep subsurface methanogens produce ~20% of the world’s methane from organic-rich coals and shales; however rates at which this energy resource is generated are unknown. In the Illinois Basin economic reservoirs of microbial methane occur in the Upper Devonian New Albany Shale associated with anomalously low salinity formation water. By determining groundwater ages the maximum timing of initial microbial methanogenesis and in-situ metabolic rates can be estimated. The plume of water with low Cl- (0.7-2154mM) and d18O values (-0.14 to -7.25‰) extends from the basin margin to >750m depth. Plume contours parallel Laurentide Ice Sheet terminal moraines, suggesting glacially controlled freshwater recharge, though d18O mixing trends and regional paleoprecipitation records indicate the primary source is precipitation with minor contributions from glacial meltwater. 4He groundwater ages could be calculated because samples contained negligible atmospheric 4He and were dominated by a crustal radiogenic source, with near complete transfer of dissolved noble gases to the gas phase. Ages ranged from 0.082-1.2 Ma, with in-situ microbial methane production rates ranging from 10-1000TCF/Ma – ~104-106 times slower than average laboratory rates. Results have implications for targeting undeveloped microbial gas accumulations, improving natural gas reservoir estimates, and understanding biologic cycling of carbon in subsurface reservoirs.
1 – University of Manchester, Manchester, United Kingdom