Estimation of Carbonate Elastic Properties Using Nanoindentation and Digital Images

Abstract

Petrophysical properties of carbonate reservoirs are less predictable than the properties of silisiclastic reservoirs. The main reason for that is chemical interaction of carbonate rocks with percolating fluids, ion exchange and recrystallization in geological time. Quantification of the elastic variability of carbonate grains on the microscale is the first step to constrain models and to obtain more realistic predictions of practically important rock properties of carbonate reservoirs. In this study we present elastic moduli of an oolite sample from the Pleistocene Dampier Formation of Southern Carnarvon Basin, Western Australia obtained by the nanoindentation technique. Young moduli of this highly heterogeneous sample are measured at 49 points regularly distributed in a 70x70micrometer rectangular grid on the surface. The frequency diagram shows bimodal distribution of the Young moduli that correspond to dense calcite phase and rare (dissolved) calcite phase. These two solid phases are apparent in the high resolution scanning electron microscope images. We used the obtained moduli of the dense and rare phases for numerical modelling of elastic properties of the carbonate sample from micro-CT images. The results of the numerical modelling using finite element code are compared with the elastic moduli obtained from acoustic velocities measured by ultrasonic technique.

An experimental study of solid matrix weakening in water‐saturated Savonnières limestone

“…; De Paula et al . ). In the majority of such experiments the so‐called grid‐indentation technique is applied (Ortega et al .…”

“…A historical overview and further details of the indentation technique can be found elsewhere (Fischer-Cripps 2004). This technique has been successfully applied to rock sample materials such as shales (Ortega et al 2007;Akrad et al 2011;Zargari et al 2013) and carbonates (Pérez-Huerta et al 2007;De Paula et al 2010). In the majority of such experiments the so-called grid-indentation technique is applied (Ortega et al 2007), in which a statistically significant number of indentation measurements are obtained from a big area of the sample.…”

Effect of supercritical CO2 on carbonates: Savonnières sample case study

“…A number of EMMs were reported to be successful in the case of carbonate rocks, including Krief's approximation ), modified upper Hashin-Shtrikman approximation (Derzhi et al (2011)), etc. The use of nano-indentation to directly measure the elastic moduli of individual phases embedded in a carbonate sample has been shown to further reduce uncertainties in the simulated effective elastic moduli (de Paula et al 2010). Another approach for selecting elastic properties of individual phases consists in using values for carbonates reported in the literature.…”