Natural molecular hydrogen in Saskatchewan, Canada.

Abstract

Natural hydrogen holds significant promise as a net-zero strategy, yet its distribution and concentration in the subsurface remain poorly understood. This thesis leverages large geodatabases to better understand the sources of natural hydrogen occurrence in Saskatchewan, Canada. The aim was to characterize the Precambrian basement, calculate hydrogen and helium production rates, and analyse 3D spatial trends in the fluid geochemistry. To achieve this, a model of Saskatchewan's basement was integrated in 3D space with radioelement data, Precambrian lithology interpretations and down well geochemical data. Hydrogen and helium production rates were calculated for basement radioelement sites and compared to the concentrations observed in down-well gas samples. A global radioelement database, combined with historical Saskatchewan data, identifies optimal hydrogen and helium source rocks and assesses Saskatchewan's natural hydrogen potential on a global scale. Results highlight the importance of understanding the crystalline basement in natural H2 exploration. Saskatchewan’s basement has a diverse composition but potentially world class radioelement concentrations and H2/He source rock in the Swift Current Anorogenic Province. Radioelement analysis of a combined global and Saskatchewan database found felsic igneous rocks to have the highest total dose rate, a metric which emerged as an effective predictor for radiolytic hydrogen potential and recommended for geodata poor regions. The distribution of H2 in Saskatchewan’s subsurface was not unambiguously resolved however some unique spatial trends were accounted for. High H2 concentrations in Mississippian strata of the Williston Basin are attributed to anthropogenic CO2 injection. When this trend is accounted for, H2 concentrations correlate more with distance from basement. Salinity was also identified as a potential control of H2 distribution but requires further study. Overall, this thesis builds on existing natural H2 knowledge to better characterize potential source rocks and explain some of the geochemical complexity which can be expected in natural H2 systems.