ИСТИНА

Information on the rock thermal conductivity is necessary for heat flow determination as well as for modeling in the petroleum industry (thermal methods of enhanced oil recovery, basin and petroleum systems modeling), geothermal energy industry, civil and underground geophysics, and radioactive waste disposal. To account for spatial and temporal variations of thermal conductivity, special theoretical models of rock thermal conductivity are applied. The most widely used model – the weighted geometric mean (so-called Lichtenecker's model) – is believed by many specialists to be relevant. We performed an analysis of the vast experimental data for different rock types including argillites, dolomites, limestones, sandstones, and siltstones (20 collections, 1765 rock samples, 33% of the samples studied at different saturation states - with air, oil, and water in pores) to test the Lichtenecker's model. The analysis showed that Lichtenecker’s model systematically underestimates significantly (up to 53%) measured thermal conductivity values for porous and fractured reservoir rocks. The average error depends on rock lithology, porosity, and pore fluid and is about 20% for dry rock samples, 14% and 9% for oil- and water-saturated samples correspondingly. Modification of the model was suggested with a correction factor following Asaad’s approach. Estimations of the factor for various lithotypes, pore fluids, and porosity were performed. Interrelation between the correction factor and pore space geometry was established using the effective medium theory for rocks from carbonate reservoirs. Methodology of the correction factor determination for reservoir rock thermal conductivity modeling was developed.