Sensitivity Analysis for the Effect of Pore Structure and Geometry on Petrophysical and Electrical Properties of Tight Media: Random Network Modeling

ABSTRACT

Several methodologies published in the literature can be used to construct realistic pore networks for simple rocks, whereas in complex pore geometry formations, as formed in tight reservoirs, such a construction still remains a challenge. A basic understanding of pore structure and topology is essential to overcome the challenges associated with the pore scale modeling of tight porous media. A stochastic random generation algorithm was employed to assess the effects of certain pore structure and geometries on the estimation of petrophysical and electrical properties of tight media through physically realistic 3D random networks. A Weibull truncated equation was used to predict the distribution of network pores and throats. An equivalent 3D pore network of Berea Sandstone was generated based on published pore and throat size distributions. The estimated porosity, absolute permeability, and formation factor of the reconstructed pore network are in good agreement with published laboratory measurements. Moreover, the estimated drainage and imbibition relative permeability curves are in a good match with corresponding experimental relative permeability curves. Subsequently, the effect of pore structure on basic core properties is evaluated by varying the Berea network pore size, throat size, and coordination number (connectivity) distributions. Finally, the effect of pore and throat geometries on two phase flow properties is investigated. The study shows the importance of taking into consideration the internal pore structure for petrophysical and electrical properties estimation.

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