Page 189 - Petrophysics 2E
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162 PETROPHYSICS: RESERVOIR ROCK PROPERTIES
Figure 3.44. Scales of reservoir beterogeneity.
sealing bed unconformities, and high permeability zones; (4) large-scale
structural features of folds and faults; and (5) the relationship of
lithofacies to depositional environment and hydraulic flow units.
OF
DISTRIBUTION ROCK PROPERTIES
Reservoir rocks are seldom if ever found to be homogeneous in
physical properties or uniform in thickness. Variation in the geologic
processes of erosion, deposition, lithification, folding, faulting, etc.
dictate that reservoir rocks be heterogeneous and non-uniform. Although
engineers have been producing oil and gas from reservoirs for more than
a century, they are still inadequately informed about the distribution of
reservoir rock properties. For a few locations in a reservoir the mineral
composition of the rock is known. Beyond this point, the real knowledge
becomes sparse. The overall problem, as stated partly by Hutchison et al.,
can be best expresse by the following three questions [47] :
How can heterogeneities be identified and classified as to extent and
geometry?
How can the extent and geometry of heterogeneities within a specific
reservoir be predicted?
How can the performance of heterogeneous reservoirs be predicted
with confidence?
