Direct measurements of fluid velocity within fractured porous media remain limited, despite their critical significance for characterizing physical and chemical processes across multiple scales -- from pore to Darcy scale -- in various subsurface geoscience applications. This study addresses this gap by presenting direct measurements of fluid flow velocity fields in a 3D-printed fractured porous medium using two distinct techniques: Magnetic Resonance Imaging (MRI) and Particle Image Velocimetry (PIV). The porous medium under investigation comprises two matrices with differing permeabilities, each containing a flow-through and a dead-end fracture. By employing MRI and PIV techniques, which differ in measuring principles, we obtain velocity values at different scales, enabling an in-depth analysis of the influence of geometric features on fluid flow behavior. Specifically, the comparison of MRI-measured and PIV-measured velocity fields encompasses aspects such as spatial distributions and probability density functions of velocity vectors and their directions. Our findings reveal noteworthy distinctions between the two techniques. The MRI technique yields values closely aligned with seepage velocity, whereas the PIV technique offers insight into pore fluid velocity. Notably, fractures exhibiting higher contrast in permeability between the matrix and the embedded fracture exhibit heightened fluid velocity. These observations, despite all fractures having identical permeability, underscore the significant impact of permeability contrast on fluid flow within fractures. This study contributes valuable insights into quantifying fluid flow exchanges between fractures and porous media. Particularly in scenarios dominated by fractures, our research sheds light on the complexities of fluid flow behavior. Overall, our findings advance the understanding of fluid dynamics in fractured porous media and hold implications for diverse subsurface applications.

