Page 26 - Petrophysics

CHAPTER 1

INTRODUCTION TO

M I N ERALOGY

Petrophysics is the study of rock properties and their interactions with
fluids (gases, liquid hydrocarbons, and aqueous solutions). The geologic
material forming a reservoir for the accumulation of hydrocarbons in the
subsurface must contain a three-dimensional network of interconnected
pores in order to store the fluids and allow for their movement within the
reservoir. Thus the porosity of the reservoir rocks and their permeability
are the most fundamental physical properties with respect to the storage
and transmission of fluids. Accurate knowledge of these two properties
for any hydrocarbon reservoir, together with the fluid properties, is
required for efficient development, management, and prediction of
future performance of the oilfield.
The purpose of this text is to provide a basic understanding of the
physical properties of porous geologic materials, and the interactions of
various fluids with the interstitial surfaces and the distribution of pores of
various sizes within the porous medium. Procedures for the measurement
of petrophysical properties are included as a necessary part of this text.
Applications of the fundamental properties to subsurface geologic strata
must be made by analyses of the variations of petrophysical properties
in the subsurface reservoir.
Emphasis is placed on the testing of small samples of rocks to
uncover their physical properties and their interactions with various
fluids. A considerable body of knowledge of rocks and their fluid flow
properties has been obtained from studies of artificial systems such as
networks of pores etched on glass plates, packed columns of glass beads,
and from outcrop samples of unconsolidated sands, sandstones, and
limestones. These studies have been used to develop an understanding

1