Synchrotron microtomography: System design and application to fluids in small channels

The Exxon microtomography facility at the National Synchrotron Light Source (NSLS) located at Brookhaven National Laboratory has constantly evolved since its first operation in 1986. This evolution has been driven by improvement in imaging technology and by research applications particularly the study of fluids in man-made structures and random porous media. The present facility provides tunable x-ray energies between 6 and 35 keV and acquires 1024 cubes of 14 bit x-ray image data with a resolution of a few microns in about one hour. Image data is reconstructed using direct Fourier inversion. We present a brief overview of the system configuration and how the application of differential absorption contrast microtomography across the iodine K edge to the characterization of multi-phase fluids in sandstones. We also present a simple method for computing the nuclear magnetic resonance T₂ relaxation spectrum directly from the CT data. Recently the system has been upgraded to radiographically image at high sped multi-phase fluid flow in small channels such as in petroleum reservoir rocks and in microelectromechancial systems. Expansion of the high speed capability to tomographic imaging of specimens in 3D in near real time is currently in progress. The upgrades improve both image acquisition and reconstruction speed by employing multi-port CCD and parallel processing technologies. We will describe the design capabilities of the high speed system and will show results from the high speed imaging of fluid flow in small tubes.