Porosity measurements of sedimentary rocks by means of microfocus X-ray computed tomography (μCT)

Porosity of reservoir rocks is an important petrophysical characteristic, used as a basic parameter in simulation studies for predicting reservoir quality. An extensive debate continues about the techniques that are available for porosity measurements and visualization. One aspect is the fact that petrophysical measurements are performed on volumetric samples, whereas classical geological petrography using a petrographical microscope is restricted to 2D analysis. This leads to a discrepancy between petrographical and petrophysical studies. This paper aims to evaluate microfocus X-ray computed tomography (μCT) as a technique that can link petrography and petrophysics. A short overview of the μCT technique is given, together with a discussion of its limitations, mainly due to artefacts. Optimization of image quality and procedures for quantification are outlined. μCT results for porosity measurements of a limestone and a sandstone are compared with results obtained by other techniques.