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The aim of the study was to examine the possibility of determining the pore space in microporous rocks using a set of methods: differential thermal analysis, retort distillation, and Dean-Stark. These methods are used for low-permeability rock containing hydrocarbons, such as shale gas, shale oil and tight gas. By using these methods it is possible to specify the amount of water contained in the sample and, consequently, determine the different levels of saturation and porosity. The study showed shale porosity values ranging from 0% to more than 5%. It was found that the samples with the highest porosities in the combustion process evolve relatively large amounts of carbon dioxide, which indicate that the porosity is related to the presence of organic matter. There was no complete correlation between the various methods׳ test results. It seems that for determining the porosity of tight shale rocks, the most effective would be the use of several complementary methods. [ABSTRACT FROM AUTHOR]

Thermal methods (simultaneous thermal analysis coupled with quadrupole mass spectrometry STA- QMS and retort) were applied to characterization of microporous rocks of different clay content. Two series of samples were investigated: highly diagenetic lower Paleozoic mudstones from Polish Lowlands and less altered Miocene and Paleocene rocks from the Carpathian Foredeep. The aim of the presented work was to differentiate between "free" and "bound" water in the pore space, to estimate the amount of fluids obtained by using retort method in regard to the distinction between free water, capillary water, clay bound water and organic matter fluids. In order to evaluate the retort results it was necessary to determine the temperatures at which a particular kind of water is released. The interpretation was based on the results of STA – QMS investigations together with XRD analysis of the mineral content, cation exchange capacity (CEC) and organic carbon content (TOC) measurements. In STA investigations the loss of mass connected with water release from clay minerals was observed in two temperature ranges: from 40 °C to 150 °C (adsorbed water) and from 440 °C to 620 °C (structural water). When analysing retort measurements, a considerable upward shift of adsorbed water release temperature can be observed. In case of Miocene and Paleocene rocks interpretation results of adsorbed water content indicate the temperature range from 150 to 450 °C, and in case of Lower Paleozoic rocks from 150 °C to 350 °C. Structural water is released at temperatures 500 °C −650 °C. A condensate connected with organic matter was observed within the temperature range 350–500 °C for Lower Paleozoic rock samples of high organic matter content (TOC>2). Taking into account the methodical discrepancies, a satisfactory compliance of results obtained by both methods in regard to the volume of clay bound water and condensate connected with organic matter was found. The results show that thermal methods can be successfully used for evaluation of saturations necessary for proper estimation of reservoir properties. • Differentiation between free and bound water by simultaneous use of STA and Retort methods. • Average content of clay bound water in early diagenetic Miocene mudstones amounts to 3,4% volume. • In Paleozoic mudstones the average content of clay bound water amounts to: 0,7% volume. [ABSTRACT FROM AUTHOR]