X-ray Computed Tomography (CT) is a nondestructive imaging technique, and its efficiency is widely recognized. In the present paper, X-ray CT is successfully applied for the visualization of water permeation process in rock. A new experimental technique using a tracer, which mainly consists of Potassium Iodide (KI), is proposed, together with the analysis method of the velocity field. The permeation process and the velocity field in rock are concretely visualized and analyzed by considering the conservation of mass of the tracers.

La tomographie calculee aux rayons X est une technique de la prise d'images non-destructive et son efficacite est largement reconnue. Dans le present expose, la tomographie calculee aux rayons X Radio est appliquee avec succès à la visualisation du procede de permeation de l'eau dans la roche. Une nouvelle technique experimentale, se servant d'un identificateur principalement constitue d'iodure de potassium (KI), est proposee avec la methode de l'analyse du champ des vitesse. Le procede de permeation et le champ des vitesse dans la roche sont visualises concrètement et analyses en considerant la conservation de masse des identificateurs.

Röntgen-Computer-Tomografie (CT) ist eine nicht-destruktive Bildverarbeitungstechnik, deren Effizienz weit anerkannt ist. In der vorliegenden Arbeit wird Röntgen-CT erfolgreich fuer die visuelle Darstellung des Wasser-Durchdringungsvorgangs im Fels eingesetzt. Eine neue experimentelle Technit mit einem Tracer, der hauptsachlich aus Kaliumiodid (KI) besteht, wird vorgeschlagen, zusammen mit der Analysemethode des Geschwindigkeitsfelds. Der Durchdringungsprozess und das Geschwindigkeitsfeld im Fels werden konkret visualisiert und analysiert, wobei die Bewahrung der Masse des Tracers beruecksichtigt wird.

Introduction

X-ray computed tomography (CT) is well known as nondestructive imaging technique. This technique has been applied for the measurements of geomaterial properties, such as soils and rock (Arthur, 1971., Verhelst et al., 1995, Otani et al., 2002). The migration of fluid fronts in rock has been studied by Cromwell et al. (1984), and the subtraction of CT images has been utilized to identify the water saturation process by Coles et al. (1991) and Sugawara et al. (1999). Through these studies, it has been revealed that X-ray CT is an effective tool for visualization of the pore structure and of transitional phenomenon such as water permeation process in rock.

In the present paper, a new experimental technique using a tracer is proposed together with the analysis method of the velocity field. In order to obtain the enough increment of CT values in rock, a new tracer, which mainly consists of Potassium Iodide (KI), is developed and the characteristics as a tracer is confirmed. One-dimensional permeation tests are performed using relatively porous stone, Kimachi sandstone, and the transportation of the tracer is visualized by X-ray CT. The velocity field in rock is also visualized and analyzed by considering the conservation of mass of the tracers.

X-ray CT scanner employed

The X-ray CT scanner employed is TOSCANER-23200, of which composition is indicated in Figure 1. A X-ray bulb of 300kV/2mA and 176 detectors are installed in a horizontal plane, and samples are set on a turntable.

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