Fast 4D imaging of fluid flow in rock by high‐speed neutron tomography

High-speed neutron tomographies (1-min acquisition) have been acquired during water invasion into air-filled samples of both intact and deformed (ex situ) Vosges sandstone. Three-dimensional volume images have been processed to detect and track the evolution of the waterfront and to calculate full-field measurement of its speed of advance. The flow process correlates well with known rock properties and is especially sensitive to the distribution of the altered properties associated with observed localized deformation, which is independently characterized by Digital Volume Correlation of X-ray tomographies acquired before and after the mechanical test. The successful results presented herein open the possibility of in situ analysis of the local evolution of hydraulic properties of rocks due to mechanical deformation.