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# Normalized Pseudo-Time

 (1)

where

 $//$ reference pressure $//$ pseudo-time  at time moment $//$ $//$ dynamic fluid viscosity $//$ total compressibility $//$ as function of time (see below)

It is widely used in Pressure Diffusion @model and transient data analysis (PTARTA ) 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.

Selection of $//$ depends on objectives.

In Pressure Build Up (PBU) survey the $//$ is calculated as sandface bottom-hole pressure$//$.

In Drawdown survey (DD) survey the $//$ is calculated as field-average formation pressure$//$.

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

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