Thermal conductivity is an important thermophysical rock property, needed for heat flow determination, deep thermal regime determination, and reconstruction of thermal history of sedimentary basin. It is generally accepted that the thermal conductivity of rocks decreases with increasing temperature and increases with increasing pressure, and the effects of temperature and pressure counteract each other. Although many measurements of thermal conductivity of the igneous and metamorphic rocks have been taken, little attention has been paid to sedimentary rocks and heat flow in sedimentary basins. Samples selected for the investigation, representing sedimentary rocks of aleuritic structure, were collected from boreholes (from deep formation, approx. 3000 m) and outcrops. The mineral composition was determined with the use of TG/DSC analysis, under inert and oxidizing atmosphere. Thermal conductivity measurements were taken with the use of C-Therm analyser, in directions parallel and perpendicular to the bedding in rock. Thermal conductivity of the examined rocks ranges from 0.96 to 6.06 W m⁻¹ K⁻¹ and is strongly dependent on mineral content and bedding direction.

The investigated rock material belongs to the group of upper cretaceous quader sandstones which are very important construction stones in Poland and Germany. The mineral composition of the rocks is relatively uniform—they are quartzose sandstones. The most important feature is their good workability and comparatively high weathering resistance. Still, regardless of the apparent resemblance, the observations carried on buildings and monuments show differences in weathering processes. The undertaken test was an attempt to verify the proposed before rock classification, performed on the basis of parameterization of porosimetric cumulative intrusion volume curves. The aim of the experiment was the evaluation of the sandstone petrography (including the structure, texture and porosity of the rock) influence on the weathering process. The modelling of accelerated weathering was conducted in Chamber for Ageing Acceleration, where some weather circumstances were simulated (insolation, rain and frost). As the result of the weathering experiment it could be stated that the dominant mechanism of the sandstones deterioration was granular disintegration and weight loss as a consequence of sample destruction. The most important factor influencing rock deterioration is rock texture, especially the character of grain contacts. The effective porosity is a requisite of potential for the stone to take in and hold water, and hence of resistance to weathering. In case of silica-cemented sandstones, the deciding criterion influencing weathering resistance is pore structure. In case of sandstones with clay cement, the most important is mineral composition of the rock.

The thermal methods, including TG and DSC techniques, were implemented to determine the composition of the fine-grained rocks with dispersed organic matter. The analyses were carried out in inert and oxidising atmosphere. The analysed samples represented Palaeozoic siltstones, shales, claystones and mudstones from Baltic Basin, Lublin Basin and Upper Silesian Coal Basin (Poland). There was detected the presence of some minerals as: clay minerals, muscovite, quartz, calcite, dolomite and pyrite. A comparison of the reactions occurring in an oxidising and inert atmosphere can give a solution to the problem of some effects overlapping, such as distinguishing pyrite decomposition from organic matter combustion. The analysis of DSC curves of heated rocks under oxidative atmosphere allows to determine the temperature regions of the organic matter combustion and to conclude on its maturity level. There was also found a strong correlation between the mass loss resulted from organic matter combustion, and the mass loss as a result of pyrolysis.

Proppant embedment is a serious issue that reduces fracture width and conductivity. The paper presents the results of experiments on embedment phenomena on a shale rock from the region of the Baltic Basin, which is regarded as an unconventional gas deposit. A novel laboratory imaging procedure was implemented to the proppant embedment visualization. The tests were performed for conditions corresponding to the average reservoir conditions occurring in the studied deposit formation. The parameters characterizing damage of the surface of the fracture faces by the grains of proppant material, after the application of axial compressive stress to two shale core samples with proppant placed in between, are presented. The tests were carried out for rock samples pre-saturated with fracturing fluid. The obtained results of relatively low total effective penetration depth of proppant grains into the walls of the fracture (0.293 mm), and high effective width of fracture with proppant material after hydraulic fracturing (87.9%), indicate the proper selection of proppant and fracturing fluid for the properties of the rock and the reservoir conditions. The results of the experiments present a range of embedment parameters, that have not been widely described before. The test procedure presented in the article is a good method for assessing the vulnerability of a deposit rock to embedment phenomenon.