Dynamic CT Reconstruction With Improved Temporal Resolution for Scanning of Fluid Flow in Porous Media

Abstract

Lab-based high-resolution Computed Tomography (μCT) is an important tool to investigate multiphase fluid flow through porous media. Rapid and continuous μCT acquisition can be used to resolve the dynamics of the 3D fluid distribution in the pores over time while the flow processes occur. However, the temporal resolution of this technique remains limited due to a trade-off between acquisition time and image quality. This work presents a method to improve the temporal resolution of multiphase flow imaging experiments by limiting the angular range of radiographs used to reconstruct each time step, while compensating for this loss of information by including a temporal total variation term in the reconstruction algorithm. This addition penalizes improper temporal fluctuations in the reconstructed images, but not those dynamic events that are consistent with the radiographs. We perform a thorough evaluation of the resulting gain in temporal resolution at the single-pore level. The method is validated on both simulated and experimental data representing multiphase flow in porous media. We find that this method improved the temporal resolution up to a factor 3 compared to reconstructions that use full 360° rotations for each time step.