We may think of rock as “solid”, but all rocks have mechanical discontinuities, generally referred to as fractures. These range in length scale from micro-cracks (µm - mm) to fractures (cm – m) to faults (m – km) and are easily affected by natural and engineered processes, causing them to open, close, initiate, coalesce and/or propagate. Furthermore, natural and engineered fluids can cause geochemical alterations that lead to crack growth or sealing through mineralization. All these changes affect the movement of fluids through fractures. Fractures can be beneficial, for example, to geothermal energy production where fluids are injected and withdrawn from subsurface rocks to extract heat. On the other hand, fractures are detrimental to subsurface sites used for storing fluids (H2, CO2) because they act as well-connected “fast” paths for fluids to leak. Thus the detection and characterization of fractures is crucial for the sustain production/isolation of fluid throughout the life-cycle of a subsurface site.
Over the last three decades, steady progress by the community has led to a deeper understanding of the hydraulic, mechanical, and seismic responses of fractures. A key finding of these efforts is the role of fracture geometry in controlling and linking these responses. In this presentation, I will highlight the importance of fracture geometry understanding the behavior of fractures.