Rodolfo Christiansen

Rodolfo Christiansen¹, Mohamed Sobh¹, Alae-Eddine Barkaoui², David Tierney³, Gerald Gabriel^1,4

¹ LIAG Institute for Applied Geophysics, Hannover, Germany

²  Université Mohammed Premier, Oujda, Maroc

³ GETECH, Leeds, United Kingdom

⁴ Leibniz University Hannover, Institute of Earth System Sciences (IESW), Hannover, Germany

This study explores a multidisciplinary approach to characterize geological conditions for advancing the understanding and quantification of natural hydrogen production in the Tendrara Basin, eastern Morocco. This region exhibits surface evidence of natural hydrogen systems through the presence of sub-circular depressions. Inspection of gravity and magnetic anomalies point to the subsurface presence of ultramafic lithologies, assumed to relate to ophiolitic suites associated with the Atlas compressional system. Our methodology spans from initial data acquisition to complex geological modelling and numerical analyses. The first stage involves establishing a comprehensive database of petrophysical, geochemical, hydrogeological, and geophysical data. This includes compiling and statistically analysing diverse datasets from various sources to ensure their accuracy and reliability. Different techniques are employed to visualize and interpret trends within the data, which is essential for deeper analysis. The next phase involves constructing detailed 3D geological models, starting from basic configurations based on geological structures and units. Advanced geostatistical methods refine these models to build detailed fault networks and geological interfaces, which are validated against empirical data from boreholes and seismic sections to improve accuracy. This modelling provides a robust framework for analysing reservoir seals and gas migration routes, which is essential for evaluating exploration potential. Subsequently, we simulate temperature distributions in the study area, crucial for assessing the potential for natural hydrogen generation. We then use a sophisticated approach to geophysical inversion to accurately determine the volumes of source rocks –serpentinized (ophiolitic) rocks in this case. Our technique integrates geological and petrophysical data, enhancing the interpretability of geological models and distinguishing between different rock types such as peridotites and host rocks based on their unique petrophysical properties. The final and most critical component of our research focuses on quantifying hydrogen production, which is important for constraining transport models and for decision makers. This involves the application of computational models that integrate critical petrophysical and geochemical data to simulate the chemical reactions and physical transformations occurring within source rocks during serpentinization. An algorithm is used to determine daily hydrogen production, adapting parameters to the unique characteristics of the study area, such as the degree of serpentinization and varying temperature windows from 100 to 400°C. In these simulations, we employ gravity and magnetic data to calculate the present-day extent of serpentinization and its impact on decreased rock density and increased magnetic susceptibility. We examine different serpentinization rates, a key parameter influencing the volume and quality of hydrogen production. These rates help estimate the velocity of the serpentinization front, a crucial factor in determining how quickly hydrogen can be produced in situ. By integrating laboratory data and historical serpentinization rates, our models provide detailed insights into the distribution of hydrogen-rich zones, and production rates. Integrating this data with 3D geological and transport models enables dynamic assessment of potential hydrogen extraction sites, ensuring well targeted and feasible exploration efforts.