Importance of Microstructure in Carbonate Rocks: Laboratory and 3D-Imaging Petrophysical Characterization

Marie Leger,Linda Luquot

doi:10.3390/app11093784

Abstract

Carbonate rocks are considered to be essential reservoirs for human development, but are known to be highly heterogeneous and difficult to fully characterize. To better understand carbonate systems, studying pore-scale is needed. For this purpose, three blocks of carbonate rocks (chalk, enthrocal limestone, and dolomite) were cored into 30 samples with diameters of 18 mm and lengths of 25 mm. They were characterized from pore to core scale with laboratory tools. These techniques, coupled with X-ray micro-tomography, enable us to quantify hydrodynamic properties (porosity, permeability), elastic and structural properties (by acoustic and electrical measurements), pore distribution (by centrifugation and calculations). The three rocks have similar properties to typical homogeneous carbonate rocks but have specific characteristics depending on the rock type. In the same rock family, sample properties are different and similarities were established between certain measured properties. For example, samples with the same hydrodynamic (porosity, permeability) and structural (formation factor, electrical tortuosity) characteristics may have different elastic properties, due to their cohesion, which itself depends on pore size distributions. Microstructure is understood as one of the essential properties of a rock and thus must be taken into account to better understand the initial characteristics of rocks.

Highlights

IntroductionCarbonate formations are considered to be useful reservoirs for human development
Carbonate formations are considered to be useful reservoirs for human development.They are often used for their resources such as water, oil and gas, and for their storage capacity or their ability to heat, such as in geothermal energy [1,2]
Once the structural-property relationships are identified at pore scale they can be replicated at large scale, facilitating large scale reservoir characterization

Summary

Introduction

Carbonate formations are considered to be useful reservoirs for human development. They are often used for their resources such as water, oil and gas, and for their storage capacity or their ability to heat, such as in geothermal energy [1,2]. Carbonate rocks are known to be highly heterogeneous, with varying properties at different scales. They are known as a complex medium, due to their formation of component particles in matrixes composed of cement and/or limestone mud [3,4,5,6]. Once the structural-property relationships are identified at pore scale they can be replicated at large scale, facilitating large scale reservoir characterization

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Discussion

Conclusion