Investigation Of The Impact Of Voxel Image Subvolume Size Upon Computed Petrophysical Properties Of Carbonate Rocks Imaged Using X-Ray Computed Microtomography
T.D. Seers, N. Alyafei and T. Khan
Event name: Second EAGE Workshop on Well Injectivity and Productivity in Carbonates
Session: Advances In Core Flooding
Publication date: 11 December 2017
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Over the past decade, significant advancements have been made in the prediction of the petrophysical properties of reservoir rocks using x-ray micro CT based digital rock physics (DRP) workflows. Such techniques now enable static and dynamic petrophysical properties, such as bulk and effective porosity, single phase permeability, capillary pressure and relative permeability to be derived directly from pore-scale images of rocks. The derivation of a comprehensive suite of petrophysical properties previously required time consuming laboratory analyses using standard core plugs, typically derived from cores, negating the use of smaller rock fragments (i.e. drill cuttings) which typically provide more representative coverage of penetrated units along the length of the well bore. In this study, the impact of subvolume dimension upon image based predictions of porosity and permeability have been investigated, in order to provide improved insights into subvolume selection in carbonate rocks. Two lithologies (Estaillades and Ketton Limestone) displaying different degrees of pore-scale heterogeneity were studied. A pore network extraction routine and a single phase simulation code have been used to estimate permeability, with voxel counts used to establish porosity. Calculations are repeated within progressively dilated kernels, enabling the statistical homogenization of petrophysical properties with increasing subvolume size to be assessed.