Perpustakaan Digital ITB

Carbonate formations still present a challenging target with regard to reservoir characterization as they possess a wide range of pore types and sizes aswell as interconnected and isolated pore space. In this study a set of micritic and oomoldic carbonate samples was investigated with three measurement techniques (magnetic resonance (NMR), mercury intrusion (MICP), and spectral induced polarization (SIP, in a frequency range from 5mHz to 100 Hz)) which provide information about a rock's pore space indirectly based on different physical principles. The aims of the study were to combine these pieces of information to characterize the pore space of mud-dominated and grain-dominated carbonate rocks and to investigate potential correlations between pore space properties and SIP-derived parameters. Pore body and pore throat size distributionswere derived fromNMR and MICP data, respectively, and interpreted in terms of dominant pore throat (rt) radius, pore body (rb) radius and the rb/rt ratio. For validation of the NMRderivedrb distributions, scanning electron microscope images were used for the computation of image-derived pore size distributions. The SIP datawere interpreted in terms of characteristic features for oomoldic and micritic samples. Phase shift, real (??) and imaginary part (???) of complex conductivity, respectively, were fitted with Cole-Cole models and the characteristic parameters relaxation time ?, chargeability m, and frequency dependence c were derived for each sample. Subsequently, these parameters were interpreted with regard to correlations with rb,rt, and rb/rt and specific surface Spor. The results indicate that grain-dominated carbonates possess comparatively large radii rb and rt and low Spor, which seems to go along with sharp phase peaks (i.e. high c values) and a lowabsolute phase level (and therefore lowchargeabilitym). The mud-dominated carbonates, in contrast, possess relatively small radii rb and rt and high Sporwhich is obviously associatedwith broad phase peaks (i.e. lowc values) and a comparatively high phase level resulting in highmvalues. ?, in contrast,was found to decreasewith increasing ratio rb/rt and may therefore have similar values in both micritic and oomoldic samples. Consequently, the results of this study contribute to a better understanding of the petrophysical properties of carbonate rocks as a function of their pore space characteristics.