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PROPERTIES OF RESERVOIR FLUIDS

A key question to ask upon discovering oil and gas is, “How much is there?”
In addition to oil or gas, there will be water and probably some gas dissolved in the
liquids. Gas also may appear as a separate phase along with oil. Properties of these
fluids are used to determine their amounts in a formation and their fluid flow charac-
teristics. This chapter describes the origin and the common methods for classifying
oil and gas resources, introduces keywords and definitions of fluid properties,
provides methods for estimating fluid properties, and shows how these properties are
measured and used in petroleum engineering.

3.1 ORIGIN

The details of the formation of oil and gas are largely unknown. From about 1860
to 1960, some debate centered on whether these fluids derived from biological or
nonbiological sources. Geochemical analysis has uncovered many molecules in
oils that share structure with chemicals in living organisms. These molecules, or bio-
markers, are fossil remains of life from millions of years ago. Hence, it is generally
accepted that oil and gas have biological origin. Many geochemists around the world
continue to research the processes of oil and gas formation. Although the details are
still being determined, we can describe the process in broad‐brush terms.

Introduction to Petroleum Engineering, First Edition. John R. Fanchi and Richard L. Christiansen.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/Fanchi/IntroPetroleumEngineering