Page 48 - Petrophysics

22 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

saturation, phase relationships of multiple fluids in porous media, and
other complex characteristics of fluid behavior in rocks have become
the new areas of petrophysical research. More emphasis is now placed
on the origin of rocks and petroleum, since the mineral composition of
the rocks and the chemical characteristics of crude oils are involved in
the fluid flow properties and the amount of residual oil saturation.
The evaluation of any petroleum reservoir, new or old, for maximum
rate of production and maximum recovery of the hydrocarbons requires
a thorough knowledge of the fluid transport properties of rocks and
the fluid-rock interactions that influence the flow of the fluids. General
knowledge of fluid flow phenomena can be gained through the study of
quarried outcrop samples of rocks. The behavior of a specific reservoir,
however, can only be predicted from analyses of the petrophysical
properties of the reservoir and fluid-rock interactions obtained from core
samples of the reservoir. Analyses of the cores only yields data at point
locations within the reservoir; therefore, the petrophysical analyses must
be examined with respect to the geological, mineralogical, and well-log
correlations of the reservoir to develop a meaningful overall performance
estimate.

OBJECTIVES AND ORGANIZATION

This text is a presentation of the theories and methods of analyses of
rock properties, and of single, multiple, and miscible phase transport
of fluids in porous geologic materials. The presentation is oriented to
petroleum engineering and is designed to provide the engineer with
the required theory, together with methods of analyses and testing, for
measurement of petrophysical and fluid flow properties for application to
reservoir evaluation, reservoir production engineering, and the diagnosis
of formation damage.
The physical and fluid transport properties of rocks are a consequence
of their pore structure, degrees of grain cementation, and electrolytic
properties. Chapter 1 therefore begins the text with a brief review of
mineralogy and the origin of sedimentary rocks. Chapter 2 is a general
discussion of the origin and composition of hydrocarbons and water
solutions of salts and gases that form an integral part of petroleum
reservoirs. Chapter 3 follows naturally from this by describing specific
rock properties, and procedures for measurement, that are important
to petroleum engineering. Porosity, permeability, surface area, etc.
are all considered in the development and prediction of the fluid
transport behavior of petroleum reservoirs. Some of these properties are
more important than others at various stages of petroleum production.
During initial development porosity, permeability, and wettability,