Units and Conversions

We have used “oilfield” units throughout the text, even though this system of units is inherently inconsistent. We chose this system because more petroleum engineers “think” in bbl/day and psi than in terms of and Pa. All equations presented include the constant or constants needed with oilfield units.

To employ these equations with SI units, it will be easiest to first convert the SI units to oilfield units, calculate the desired results in oilfield units, then convert the results to SI units. However, if an equation is to be used repeatedly with the input known in SI units, it will be more convenient to convert the constant or constants in the equation of interest. Conversion factors between oilfield and SI units are given in Table 1-1.