Numerical petrographic pore system analysis: Implications for geothermal reservoir characterization of the Muschelkalk in Northern Germany

In this study, the effect of different Lower Muschelkalk Schaumkalk fabrics on pore system properties have been investigated to understand the permeability heterogeneity of this potential geothermal reservoir facies. A combination of permeability mapping and numerical petrographic pore system analysis has been used to identify high-permeability fabrics which are then analysed for their effective pore types. Locally concentrated zones of vug-formation as well as the occurrence of laminae dominated by molds of bivalves highly elevate permeability as compared to the typical “Schaumkalk” fabric with an inverted pore system dominated by moldic pores. The highest permeability measured is tied to the coquina fabric. The method presented offers a novel tool of numerical pore system analysis for determination of pore type properties and prediction of permeability heterogeneity at an unprecedented level of accuracy.