# Pseudo Steady State

## Definition - What does Pseudo Steady State mean?

Pseudo Steady State is the period in which hydrocarbons in a reservoir flow in a steady state into the well. It can also be referred to as the “stabilized” flow condition from a bounded drainage area. In a Pseudo Steady flow, the pressure at various locations in the reservoir linearly declines as a function of time and remains constant at every point.

## Petropedia explains Pseudo Steady State

A Pseudo Steady state flow condition can be expressed mathematically in the following formula:

This means that the change in the rate of pressure with respect to time at every point in a reservoir is constant.

In a constant production rate, the difference between the pressure created by the fluid flowing in a wellbore and reservoir pressure in the drainage area remains constant. This results in a uniform slope when plotted on a Cartesian plot.

There are three types of flow regimes which describes the behavior of fluid flow through a reservoir

- Steady state flow
- Semi steady state flow
- Unsteady state flow