Petrophysical characterization, BIB-SEM imaging, and permeability models of tight carbonates from the Upper Jurassic (Malm ß), SE Germany

Abstract Tight carbonate rocks are important hydrocarbon and potential geothermal reservoirs, for example, in CO 2 -Enhanced Geothermal Systems. We report a study of outcrop samples tectonically undeformed tight carbonates from the upper Jurassic “Malm ß” formation Southern Germany near town Simmelsdorf (38 km NE Nuremberg) to understand bulk petrophysical properties relation microstructure compare models permeability prediction these samples. applied Archimedes isopropanol immersion, Helium pycnometry, mercury injection, gamma density core logging, gas measurements, combined with microstructural investigations liquid metal injection (LMI-BIB-SEM). In addition, ultrasonic velocity was measured allow geomechanical comparison stratigraphically equivalent South German Molasse Basin (SGMB). Results show only small variations, showing that is rather homogeneous porosities below 5% argon permeabilities around 1.4E−17 m . The presence stylolites some has neither significant effect on porosity nor permeability. Pores submicron size pore throats 10 nm connected as shown by Mercury Liquid Metal injection. Samples have high dynamic Young’s Modulus 73 ± 5 GPa expected lithified diagenetically overmature limestones. Moreover, no trends were observable toward faults at meter scale, suggesting faulting post-diagenetic matrix too low intensive fluid–rock interaction. Petrophysical very close those SGMB, illustrating widespread homogeneity justifying quarry reasonable reservoir analog. Permeability models, such percolation theory-based Katz-Thompson Model, Poiseuille-based like Winland, Dastidar, capillary tube, Kozeny-Carman Models, well several empirical namely, Bohnsack, Saki, GPPT applied. It tube Model Saki best suited predictions BIB-SEM pressure results, respectively, providing method estimate subsurface drill cuttings. Matrix primarily controlled (throat) diameters than effective porosity.