Page 187 - Petrophysics

160 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

TABLE 3.6
SUMMARY OF RESULTS

kw
Equal Kaolinite-Illite
0.58 0.35 1.66
0.58 0.35 1.66
0.58 0.4 1.45
High Illite
0.58 0.11 5.27
0.58 0.15 3.87
0.58 0.37 1.57

rocks varies from pore level to field level. Consequently, petrophysical
properties are better understood by using the scales of heterogeneity.

Microscopic Heterogeneity
The microscopic scale of heterogeneity represents the scale volume
at which the rock properties such as porosity and permeability are
determined by: (1) grain size and shape; (2) pore size and shape; (3) grain,
pore size, and pore throat distribution; (4) packing arrangements;
(5) pore wall roughness; and (6) clay lining of pore throats, etc. The
major controls on these parameters are the deposition of sediments
and subsequent processes of compaction, cementation, and dissolution.
Microscopic scale parameters are measured using scanning electron
microscope (SEM), pore image analysis (PIA), magnetic resonance
imaging (MRI), and nuclear magnetic resonance (NMR).

Macroscopic Heterogeneity
Core analysis represents the domain scale of macroscopic heterogeneity.
Laboratory measurement of porosity, permeability, fluid saturation,
capillary pressure, and wettability are physically investigated at the
macroscopic level. Rock and fluid properties are determined to cdibrate
logs and well tests for input into reservoir simulation models.

Mesoscopic Heterogeneity
Information on this scale of heterogeneity is collected from well logs.
They are represented at grid cell scale in the reservoir simulation where
variation in rock and fluid properties, along with small-scale geological
features, is averaged to be assigned single values for the whole grid
block. Core calibrated well logs are used to: (1) establish the correlations