Page 153 - Petrophysics

126 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

(c) Calculate the flow zone indicator(FZI) from Equation 3.45:

&=-- @e - 0.15 = 0.176
1-& 1-0.15

RQI 0,519
--
-
FZI = - - 2.95p.m
-
Oz 0.176
(d) The Tiab flow unit characterization factor HT is:
1 1
FIT=-=--- - 0.1 15 ym-2
FZ12 2S2
Accurate estimates of reservoir rock parameters should not be
made from log data alone. A judicious combination of core analysis
and log data is required to link these parameters in order to
achieve a more global applicability of the equations and relationships
presented here. A consistent and systematic approach is required
to integrate such petrophysical data in order to develop meaningful
relationships between microscopic and macroscopic measurements.
The flow chart in Figure 3.21 provides such an approach. The chart
indicates the different steps for identifying and characterizing flow
units in clastic reservoirs. This zoning process is best suited for
reservoirs in which intergranular porosity is dominant. Because of the
similarity in distribution and movement of fluids within clastic and
carbonate rock having intercrystalline-intergranular porosity, this
zoning process can be directly applied to these reservoir systems.
This process is, however, not applicable to carbonate reservoirs with
vugular solution channels and/or fractures.

EXAMPLE

Assuming that the permeability and porosity data shown in Table 3.4
are representative of several hundred data points taken from an oil
reservoir:

(a) Identify the number of flow units and their corresponding values
of flow zone indicator, FZI, and the Tiab flow unit characterization
factor, HT.
(b) Calculate tortuosity and plot versus reservoir quality index, RQI, on
a log-iog graph. Does this plot confirm the number of flow units?
(c) Calculate the free fluid index (FFI) and plot versus RQI on a
log-log graph. Interpret this plot. The irreducible water saturation is
approximately 5%.