Experimental estimation of specific surface area of bazhenov oil shale and factors controlling its increase
As reserves from traditional hydrocarbon traps are increasingly depleted, the development of shale oil resources moves into focus. When developing new technologies for hydrocarbon production from low-permeable reservoirs rich in organic matter, such as Bazhenov oil shale, it is extremely important to correctly estimate the sorption capacity of the rock surface. This theoretically should depend on the amount and characteristics of organic matter and the ratio (proportion by content) of three rock-forming minerals, silica, carbonate, and clay, which are present in Bazhenov rocks with a significant predominance of silica. In the present work, for the first time, experimental laboratory studies of N 2 and H 2 O vapor sorption were carried out on a specially selected collection of rock samples of different thermal maturity from the Bazhenov Formation in oil and gas fields in western Siberia. The specific surface area of Bazhenov rocks has been estimated experimentally by the adsorption of nitrogen and water vapor using the BET method. The values obtained by nitrogen adsorption vary from 3.6 m 2 /g to 7.9 m 2 /g and depend on several factors, including thermal maturity of kerogen. The estimates based on vapor adsorption correlate with the clay content. The analysis reveals several peculiarities of the pore space of Bazhenov rocks, including a substantial fraction of isolated porosity and a substantial hydrophobic surface area in a mature sample, presumably within the organic phase.
