Petrophysical Characteristics of Silurian Mudstones from Central Taurides in Southern Turkey

This study used a range of integrated and complementary experiments to examine pore-structure, fluid-shale wetting characteristics, sample size-dependent porosity towards different fluids, and imbibition behavior, as well as the relationships between these properties and the mineralogy of Silurian mudstones in the Central Taurides of Turkey. Working with different sample-sizes, the experiments consisted of helium pycnometry, low-pressure nitrogen physisorption isotherm, mercury intrusion porosimetry, fluid immersion porosimetry, liquid displacement, fluid droplet wettability and contact angle measurements, and spontaneous imbibition of fluids; four fluids with different hydrophilicity were used to assess the characteristics of fluid-shale interaction and its influence on pore-structure. Results show that studied mudstones can be grouped into three rock types: siliceous, carbonate-dominated, and mixed mudstones. Siliceous and mixed mudstones have higher porosities, pore-throat diameters, surface areas and tortuosities than the carbonate-dominated mudstones, regardless of sample sizes and fluids used. With low permeabilities and medium pore-throat sizes for the siliceous and mixed mudstones, the wettability and imbibition results show that these mudstones are both oil-wet and moderately-to-high water-wet. In contrast, the carbonate-dominated mudstones exhibit oil-wet characteristics. These results indicate that studied siliceous and mixed mudstones in the Central Taurides seem to have appropriate petrophysical properties in the context of reservoir quality.