How does PowerTools calculate the Z factor?
A. PowerTools calculates the real gas deviation, or Z factor (Z), for hydrocarbon gases. The technique used by this program was developed by Dranchuk, Purvis, and Robinson. The Benedict-Webb-Rubin equation of state is fit to the Z factor surface defined by the Standing-Katz Z factor correlation. The resulting nonlinear equation is then solved for Z as a function of reduced temperature and pressure using Newton-Raphson iteration. The Dranchuk, Purvis, and Robinson correlation has the lowest average error of the eight most commonly used methods for estimated Z factors.
PowerTools calculates the real gas deviation, or Z factor (Z), for hydrocarbon gases. The technique used by this program was developed by Dranchuk, Purvis, and Robinson. The Benedict-Webb-Rubin equation of state is fit to the Z factor surface defined by the Standing-Katz Z factor correlation. The resulting nonlinear equation is then solved for Z as a function of reduced temperature and pressure using Newton-Raphson iteration. The Dranchuk, Purvis, and Robinson correlation has the lowest average error of the eight most commonly used methods for estimated Z factors.
