Page 135 - Percolation Models for Transport in Porous Media With

Chapter 7

Methods for Determining

Parameters of :Fractured

Rocks

Investigation of the cores brought to the surface is one of the most widespread
methods for studying various types of rocks. At present, methods for determining
the coefficients of permeability for grained and cavernous reservoir rocks, based on
experimental study of cores from the productive layer, are well enough developed.
Since in general the sizes of pores or caverns are much less than the dimensions
of the core, the latter is in essence a macroscopic volume which can be studied to
get information about the rock.
In the case of a fractured medium the lengths of fractures can be commensu-
rate with the characteristic dimension of the core or even exceed this dimension.
Therefore the permeability of the core of a fractured reservoir rock cannot be iden-
tified with the permeability of the productive layer. Due to this fact there are two
possible approaches to the obtaining of reliable information about the permeabil-
ity of such a reservoir rock. One should either study the coefficient of permeability
for the cores with characteristic dimensions much greater than the average length
of fractures in the rock, or develop mathematical methods for processing the re-
sults of research on the cores of usual dimensions to obtain information about the
whole body. Obviously the second approach is preferable from the technological
feasibility viewpoint. It must be taken into account, however, that the only piece
of information there can be obtained during the study of the core of a fractured
reservoir rock is the information about the parameters of the traces left by the
fractures on the surface of the core.

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