Virtual core laboratory: Properties of reservoir rock derived from X-ray CT images

We demonstrate that accurate predictions of petrophysical properties can be made directly from digitized tomographic images. Computations of both transport (formation factor and permeability) and elastic properties from micro-tomographic images of a suite of Fontainebleau sandstone are shown to be in excellent agreement with experimental measurements over a wide range of porosities (5% < φ < 25%). Four small (5 mm i.d.) plugs from a producing gas field have also been analysed. Unlike Fontainebleau, these four cores exhibit a broad range of pore and grain sizes, porosity and mineralogy. Computations of permeability and capillary pressure are made directly on the digitized tomographic images and compared to laboratory core measurements. The results are in excellent agreement. The very small sample size required for imaging may allow representative petrophysical data to be obtained from sidewall cores and drill cuttings.