Network extraction from sandstone and carbonate pore space images

A methodology for extracting networks from pore space images is presented. It computes the location and sizes of pores and throats to create a topologically equivalent representation of the void space of three-dimensional (3D) rock images, using the concept of maximal balls [Silin, D.B., Jin, G. and Patzek, T.W., 2003. Robust Determination of the Pore Space Morphology in Sedimentary rocks. SPE 84296, Annual Technical Conference and Exhibition, Denver, Colorado, USA, October.]. The model is successfully tested on sandstone and carbonate samples. The network extracted from a representation of Fontainebleau sandstone yielded a coordination number distribution that agrees well with that computed using a different extraction algorithm that is based on knowing the location of grain centers [Øren, P. and Bakke, S., 2003. Reconstruction of Berea sandstone and pore-scale modelling of wettability effects. Journal of Petroleum Science and Engineering 39 177–199.]. The model was further tested on a carbonate sample from subsurface Oman for which it is not possible to identify grains easily. For all the samples investigated in this study, the predicted absolute permeabilities, using the newly extracted networks, agree well with the laboratory measured values.