Page 120 - Reservoir Formation Damage

Characterization of Reservoir Rock 103

(Kersey, 1986; Amaefule et al., 1988; Unalmiser and Funk, 1998). Some
methods, such as well test interpretation, may be used to infer for limited
information on a few critical parameters of reservoir formation. However,
direct measurements of core properties at reservoir conditions are pre-
ferred, because they provide the most realistic information about the
petroleum-bearing formations.
The fundamental analytical techniques available for laboratory evalu-
ation of core samples for sensitivity and damage potential are briefly
described in this chapter. For operational principles and detailed descriptions,
the readers are referred to manufacturers' manuals and other pertinent sources.

Formation Evaluation

Knowledge of reservoir formation characteristics is essential infor-
mation required for studies of reservoir formation damage and inter-
pretation of laboratory and field tests. As stated by Doublet et al. (1995),
"Reservoir properties and heterogeneities can be effectively defined
using four scale levels (Doublet et al., 1995 credit; Kelkar, 1991, 1993
for this information):

• Microscopic
— micro scale data
— pore and grain size distributions
— pore throat radius
— rock lithology
• Macroscopic
— core scale data
— permeability
— porosity
— saturation
— wettability
• Megascopic
— simulator grid block scale data
— wireline logs
— seismic data
• Gigascopic
— reservoir scale data
— pressure transient tests
— geologic model"

The extent of the information required depends on the scale of the
studies planned. Various techniques are being developed for measurement