Laboratory-scale muography experiments to estimate density and saturation in porous media

Cosmic-ray muons are naturally abundant, high-energy particles that can probe geological structures. Muography exploits muon attenuation or scattering to infer density variations, offering a non-invasive and cost-effective method for subsurface studies. We present laboratory and Monte Carlo simulation evidence for density estimation of porous media with varying fluid saturation, measured by coincident muon flux using plastic scintillator detectors. Muon flux was recorded after transmission through acrylic and sand samples of known density and thickness, and the results were validated against simulations that tracked attenuation as a function of density. Muon flux attenuation systematically reflected changes in material density and fluid saturation. Using a Gaussian-filtered dataset and an exponential model, the estimated bulk density of acrylic closely matched the known value (1.19 g cm⁻³), with relative errors decreasing from 11.1% at 20 cm to 0.34% at 80 cm. For variably saturated sands, densities ranged from 1.01 ± 0.12 g cm⁻³ (0% saturation) to 1.54 ± 0.13 g cm⁻³ (100% saturation), with relative errors improving from 21.1% to 10.8%. Numerical simulations reproduced the same attenuation trends, with errors of less than 1%. These findings demonstrate muography’s sensitivity to subtle density variations, highlighting its potential for reservoir monitoring and imaging density-linked fluid dynamics. Laboratory and simulation results demonstrate that absorption muography effectively quantifies bulk density and fluid saturation in porous sand. Muon flux attenuation scales with density-length, resolving small changes and supporting noninvasive reservoir monitoring.