Pseudo Pressure

Introduction

Pseudo-variable transformations are commonly used to account for fluids that have strong pressure dependencies of fluid and rock properties. Pseudo-pressure is a mathematical pressure function that accounts for the variable compressibility and viscosity of a fluid.

For gas scenarios, pseudo-pressure is defined as follows, and is a function of both viscosity and gas z-factor .

which is the original real gas pseudo-pressure definition.

This defintion can also be normalized to real units by:

References:

• Agarwal, Ram G. “Real Gas Pseudo-Time" - A New Function For Pressure Buildup Analysis Of MHF Gas Wells." Paper presented at the SPE Annual Technical Conference and Exhibition, Las Vegas, Nevada, September 1979.

• Al-Hussainy, R., Ramey, H.J., and P.B. Crawford. "The Flow of Real Gases Through Porous Media." J Pet Technol 18 (1966): 624–636.