porosity) and makes thus reservoir quality prediction difficult. This complexity in the microstructure will translate in complex relationship between geophysical observables and rock parameters (e.g. Compared to siliclastic rocks, carbonate rocks exhibit a far more complex microstructure, which is the result of both deposition and transport processes of fossiliferous materials containing intraporosity, as well as of diagenetic alterations (dissolution/precipitation) that leads to complex changes in the initial microstructure. Rocks are heterogeneous at all scales, from the pore scale upwards. Scanning Electron Microscopy (SEM) imaging of the same probed areas allowed to correlate micrite microstructure to elastic properties: the more microporous micrites displayed Young’s moduli as low as 9 GPa and the tighter ones as high as 64 GPa. Because the length scale of heterogeneities of the probed areas was larger than the indent size, the samples can be seen as composites of different phases and upscaling rock physics models such as self-consistent approximation can be used to get the effective elastic properties. Results show a broad distribution of moduli, from very low values to values consistent with calcite mineral. In this study, we used nanoindentation technique to map Young’s modulus of microporous limestones at the microscale (map of 300*300 µm 2, with a step measurement of 10 µm).

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