A method for determining the porosity of core samples of ultra-low-permeability rocks is presented and tested. The core samples of the Bazhenov formation were the object of research. The proposed method is based on the GRI method (Gas Research Institute), adapted for rocks of the Bazhenov formation. To calculate the coefficient of gas-saturated and open porosity, bulk and mineralogical densities were determined both for samples in a state of natural saturation and after extraction.

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... of bulk density was carried out by the gas-volumetric method and the modified method of liquid saturation. Determination of the mineralogical density was carried out by the gas volumetric method. The measurement of water saturation of the crushed core samples was carried out in the Dean-Stark apparatus. The gas saturation of core samples was calculated based on the results of determining the coefficient of gas-saturated and open porosity. Gas saturation was calculated based on the results of determining the coefficient of gas-saturated and open porosity. The oil saturation was determined by the calculation method based on the material balance.