Resolution dependence of petrophysical parameters derived from X-ray tomography of chalk

Dirk Müter, Henning Osholm Sørensen, Diwaker Jha, Ralph Patrick Harti, Kim Nicole Dalby, H. Suhonen, Robert Krarup Feidenhans'l, F. Engstrøm, Susan Louise Svane Stipp

30 Citationer (Scopus)

Abstract

X-ray computed tomography data from chalk drill cuttings were taken over a series of voxel dimensions, ranging from 320 to 25 nm. From these data sets, standard petrophysical parameters (porosity, surface area, and permeability) were derived and we examined the effect of the voxel dimension (i.e., image resolution) on these properties. We found that for the higher voxel dimensions, they are severely over or underestimated, whereas for 50 and 25 nm voxel dimension, the resulting values (5%-30% porosity, 0.2-2 m2/g specific surface area, and 0.06-0.34 mD permeability) are within the expected range for this type of rock. We compared our results to macroscopic measurements and in the case of surface area, also to measurements using the Brunauer-Emmett-Teller (BET) method and found that independent of the degree of compaction, the results from tomography amount to about 30% of the BET method. Finally, we concluded that at 25 nm voxel dimension, the essential features of the nanoscopic pore network in chalk are captured but better resolution is still needed to derive surface area.

OriginalsprogEngelsk
Artikelnummer043108
TidsskriftApplied Physics Letters
Vol/bind105
Antal sider5
ISSN0003-6951
DOI
StatusUdgivet - 28 jul. 2014

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