Perm Journal of Petroleum and Mining Engineering (Sep 2015)
The results of dispersion factor analysis in verifying a structure of pore space in reservoir rocks
Abstract
The paper offers some results of dispersion factor analysis in classifying carbonate rocks according to pore space. The radius of pore channels and pore tortuosity were chosen as effective parameters. The analysis demonstrates a correlation between a pore channel radius and pore space structure except for distinguishing "pure" pore space and pore-cavernous/cavernous structures, as well as cavernous and fractured structures of carbonate rocks at the Bashkir anticline deposits. For deposits of the Solikamskaya depression the fidelity values obtained (except for the parameter distinguishing pore and pore-cavernous structures) are higher than tabular values for a certain significance level. As for pore tortuosity of channels, this parameter is informative only to distinguish "pure" pore and fractured structures, as well as cavernous and fractured reservoirs located in the Solikamskaya depression. The results testify to different processes of cavern and fracture formation in the Famennian-Tournaisian deposits of the Bashkir anticline and Solikamskaya depression. Cavernosity in the Famennian-Tournaisian deposits of the Solikamskaya depression is found to extend uniformly and more active than in the deposits of the Bashkir anticline. Microdescription of core samples taken from the Solikamskaya depression confirms that the Famennian-Tournaisian cement rocks of this location were transformed in a more expressed manner than their counterparts of the Bashkir anticline. This is shown by intensive desalination and relation of cavernosity and fracturing to compact variety. The maximum number of cavernous rocks in these deposits corresponds to poor-pore intervals (0-3 %), their portion being 60 %, while the cavernous varieties among poor-pore rocks (Kp < 3 %) in the the Bashkir anticline makes less than 2 %.
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