The contribution of very high resolution drone-borne aeromagnetic survey (VHRAM) for resources exploration in faulted reservoirs and application in the Upper Rhine Graben

Abstract Faulted reservoirs are key targets for geothermal resources as well as lithium extraction but their exploration at great depth faces great technological challenges. Recent advancements in drone and magnetic sensors have enabled the integration of measuring systems on light drones, allowing a great increase of resolution of measurements. This study presents the successful execution of a very-high resolution aeromagnetic survey (VHRAM) at 50 meters above ground level using drones. The results were compared with regional interpretations of the Upper Rhine Graben from a helicopterborne survey and seismic data. The drone-based survey provided a significant increase in resolution, enhancing the interpretation of local geological features, particularly the basement rock structures and the pre- and syn-rift sediments in the fractured areas along the basin borders. A key finding was the ability to detect structural features in the basement at depths of several kilometers which were not observable in the regional survey and interpretation from seismic data. This very high resolution data, when combined with a reinterpretation of historical seismic lines, allowed for a refinement of the geological model, highlighting a structural node in the area. Although the UAV survey covered a relatively small area, its impact was significant, offering valuable insights at the scale of typical exploration permits. These results validate the feasibility and effectiveness of very-high-resolution magnetic surveys (VHRAM) using lightweight drones at low altitudes for fault network characterization in geothermal resource exploration.