Non-destructive core analysis using X-ray computed tomography

Abstract

X-ray computed tomography (CT) is a non-destructive means by which the internal structure of an object may be viewed. It produces a digital image that is a map of the X-ray attenuation in a slice through the object. At Curtin University, this technique has been successfully applied in the analysis of various rock materials, including four inch diameter cores from the petroleum exploration industry. Two scanners, an EMI CT5005 (second generation machine) and a Siemens SOMOTOM DR/H (third generation), both in routine medical use at local Perth hospitals, have been used in this work. Interpretation of X-ray CT results is facilitated by high resolution colour graphic display on a Landmark seismic workstation. CT images have revealed sedimentological and structural features in cores that are, in some cases, quite unexpected, and would not be apparent utilizing conventional (i.e. destructive) core analysis techniques. X-ray CT has much potential for core characterisation and reservoir modelling; it can measure mineral distributions, depositional textures, porosity variability, fracture frequency and orientation, and fluid saturations. Core quality parameters such as the degree of drilling mud invasion can also be assessed. Importantly, X-ray CT can image the internal structure of sealed (i.e. preserved at the rig site) cores.