An image analysis contribution to the study of transport properties of low-permeability crystalline rocks

Transport properties of the Charroux-Civray tonalite matrix were studied by a two-dimensional mufti-scale model, based on image analysis procedures. T he estimation of a transport coefficient of the matrix was obtained by comb ining the 2-D image of the spatial arrangement of primary mineral phases wi th the aperture distribution of microscopic pathways. The study focused on one fresh facies and one fairly altered facies. Connectivity of the fluid f low network varied according to the studied facies. It is shown that pathwa ys inside dark minerals and quartz, exert a lower influence on the transpor t coefficient than pathways inside feldspars. Strong assumptions used in th e presented numerical method do not allow direct comparison between real tr ansport coefficients and factors determined by the model. However, for both facies studied, comparison between simulated transport coefficients and ex perimental permeability suggests that the calculation hypothesis needs to b e improved: the real aperture of microcracks must be taken into account, an d a large number of classes of aperture are required for this kind of simul ation. (C) 2001 Elsevier Science Ltd. All rights reserved.