P_{\Psi}(p) = \frac{p_{ref} \cdot \Psi(p)}{\Psi(p_{ref})} = p_{ref} \cdot  \int_0^p \frac{p \, dp}{\mu(p) \, Z(p)} \Bigg/  \int_0^{p_{ref}} \frac{p \, dp}{\mu(p) \, Z(p)}

where

	reference pressure
	Pseudo-Pressure at reference pressure
	Pseudo-Pressure at pressure
	dynamic fluid viscosity
	fluid compressibility factor

It is widely used in Pressure Diffusion @model and transient data analysis (PTA / RTA ) of strongly compressible fluids.

The choice of reference pressure is made by engineer depending on common sense and objectives of the study.

The usual practise is to select as the bottom-hole pressure at initial time moment.

In case the Normalized Pseudo-Pressure is used to linearize the Pressure Diffusion equation the choice of reference pressure is not going to affect the solution.

Normalized Pseudo-Pressure does represent a pressure in terms of physical property and has the same dimension unlike Pseudo-Pressure.

See also