Page 49 - Petrophysics

OBJECTIVES AND ORGANIZATION 23

together with hydrocarbon saturation, are important; but at later stages
of development, especially if enhanced recovery techniques (EOR) are
being considered, pore size distribution, surface area, and capillary pres-
sure become very important petrophysical properties in the planning and
design of continued reservoir development.
Chapter 4 presents various fundamental theories establishing quanti-
tative and qualitative relationships among porosity, electrical resistivity,
and hydrocarbon saturation of reservoir rocks. A brief discussion of
core analysis, well logging, and well testing is included. Laboratory tech-
niques for measuring core properties are presented in the Appendix. Well
logging techniques are presented solely for the purpose of explaining
the applications of the Archie and Waxman and Smits [34] equations.
A discussion is included on how well logs provide data not directly
accessible by means other than coring; and how well logs can be used
to extend core analysis data to wells from which only logs are available.
Several field examples are included in this chapter.
Capillary pressure and its measurement by several methods are
presented in Chapter 5. Laboratory techniques (semi-permeable disk,
mercury injection, and centrifuge) are presented for measuring capillary
pressure. Chapter 6 is in many ways an extension of the capillary
phenomena to the measurement and determination of the influence
of wettability on oil recovery, pore size distribution, and relative
permeability. Methods for determining the wettability index are also
included in this chapter.
The flow of fluids (oil and gas) through porous rocks is presented
in Chapter 7. The analysis of linear, laminar flow is followed by a
discussion of radial and turbulent flow. Equations for calculating the
average permeability of naturally fractured rocks and stratified formations
are derived in this chapter. This chapter concludes with a discussion of
rocks of multiple porosity.
Chapter 8 is a discussion of naturally fractured rocks and their
properties.
The effect of stress on reservoir rock properties, including
permeability, porosity, compressibility, and resistivity, is the subject of
Chapter 9. The mechanical properties of rocks are very important when
designing drilling, well completion, production, and field development
programs. Laboratory techniques for measuring elastic properties of
formation rocks are discussed. Also, a number of correlations used to
predict the behavior of these elastic properties are included.
Chapter 10 presents a discussion of the transport properties of
discrete particles in porous geologic materials. Fine rock particles
and precipitated particles from fluids tend to migrate to production
wells where they decrease production by plugging the rock pores.