Page 8 - Fundamentals of Reservoir Engineering

PREFACE / ACKNOWLEDGEMENTS VIII

A difficult decision to make, at the time of writing, is which set of units to employ.
Although the logical decision has been made that the industry should adopt the SI
(Système Internationale) units, no agreement has yet been reached concerning the
extent to which "allowable" units, expressed in terms of the basic units, will be
tolerated. To avoid possible error the author has therefore elected to develop the
important theoretical arguments in Darcy units, while equations required for application
in the field are stated in Field units. Both these systems are defined in table 4.1, in
Chapter 4, which appropriately is devoted to the description of Darcy's law. This
chapter also contains a section, (4.4), which describes how to convert equations
expressed in one set of units to the equivalent form in any other set of units. The
choice of Darcy units is based largely on tradition. Equations expressed in these units
have the same form as in absolute units except in their gravity terms. Field units have
been used in practical equations to enable the reader to relate to the existing AIME
literature.