Geoffrey S. Ellis, U.S. Geological Survey, Denver, Colorado, USA (email@example.com)
Daniel Palmowski, Terranta GmbH, Aachen, Germany
Nicolas Lefeuvre, Université Grenoble Alpes, Grenoble, France
Interest in natural hydrogen as a primary energy resource has grown significantly in recent years. The geologic concepts required to understand the processes that could produce economic hydrogen accumulations are expanding along with the efforts to explore for natural hydrogen resources. The concept of the ‘hydrogen system’ is now evolving from the framework of the petroleum system with adopted elements from geothermal and hydrothermal mineral exploration. However, effective strategies for hydrogen resource exploration will require tools to apply the hydrogen system model to natural systems. Adopting workflows from hydrocarbon and mineral exploration, two- and three-dimensional reactive transport modeling software potentially offers an effective approach to test hypotheses and concepts. Model predictions can be compared with field observations to efficiently provide validation of predictions of hydrogen system components. We will present a case study from a site of active hydrogen exploration in the Mauléon Basin in the Northern Pyrenees of France where soil gas hydrogen anomalies have identified the possible presence of a viable hydrogen system. The model inputs include the structural geometry and lithostratigraphy of the study area as well as the inferred hydrodynamic regime. Coupled fluid-flow and chemical reaction (thermodynamic equilibrium or kinetic) calculations allow for assessing and quantifying key geological constraints on the effectiveness of the hydrogen system from source to trap. For example, rates of hydrogen generation or migration along faults can readily be estimated. We will demonstrate the utility of this approach for derisking natural hydrogen exploration by evaluating geologic and geochemical concepts and validation with field data.