Page 502 - Petrophysics
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470 PETROPHYSICS: RESERVOIR ROCK PROPERTIES
n
Figure 7.12. Three-layer reservoir with crossflow.
If the thickness also varies, Equation 7.143 becomes:
(7.144)
where n is the total number of layers. If the porosity, thickness, and
compressibility vary from layer to layer, then:
(7.145)
If the total permeability-thickness product, (kh)t, is known from a
pressure test, individual layer permeabilities may be estimated from the
following equation:
(7.146)
where qi is the volumetric rate of fluid flow through each layer.
Equation 7.146 is valid only if the individual skin factors are all equal
or negligible.
LAYERED RESERVOIRS WITHOUT CROSSFLOW
In many oil and gas pools, the reservoir rocks are interbedded with
impermeable shales beds and silt laminations, such that there is no
crossflow between the oil- and gas-saturated sand beds.
