Multiphase Flow Characterization Using Simultaneous High Resolution Neutron and X-Ray Imaging

Abstract:

Multiphase flow in geologic materials is an important area of research for hydrology and oil recovery. A valuable tool for determining how liquid water and/or hydrocarbons transport through soils and rocks is neutron tomography due to its high sensitivity to hydrogen. This technique allows for the 3D reconstruction of the liquid phase in the sample. In order to resolve the solid phase structure of the sample it is necessary to perform x-ray tomography which often must be conducted at a separate facility from the neutron imaging. When imaging deformable samples or stochastic flow this delay in imaging modes ruins the analysis as the sample is no longer in an identical state. To address this issue and bring a unique capability to NIST, an instrument has been commissioned for the simultaneous imaging with neutrons and x-rays. The new system orients a micro-focus 90 kV x-ray beam 90° to the neutron beam which facilitates rapid dual-mode tomography of samples. Current highest spatial resolutions are 20 µm and 10 µm for the neutron and x-ray detectors, respectively, with upcoming improvements. This presentation will focus on introducing the new system and demonstrating its ability with several cases. Examples of high resolution water uptake and high speed imaging of uptake dynamics will be given.