Chapter 6 - Neutron transmission tomography applied to reactive dissolution through percolating porous media

Abstract

This chapter describes a neutron imaging facility that can be operated in the radiographic mode to obtain two-dimensional transmission images having a high degree of spatial resolution or in the radioscopic mode to image dynamic events. Both systems can be used in conjunction with computer tomography for three-dimensional imaging. To demonstrate the imaging technique, neutron radiography, neutron radioscopy, and neutron transmission tomography were applied to the reactive dissolution of carbonate porous media, a process pertinent to the stimulation of petroleum reservoirs. Neutron transmission tomography is a three-dimensional imaging technique ideally suited for imaging flow and reaction in porous media. The computer tomography (CT) based technique provides excellent contrast between substances containing hydrogen or cadmium and host materials, such as consolidated porous media and most metals. The technique provides moderate contrast when stainless steel is the host material. Previous investigators have applied this technique to the inspection of nuclear fuel assemblies, the non-destructive testing of large metallic objects, the imaging of hydrocarbon sprays inside metallic structures, and the imaging of water saturation in dolomite core samples.