...
Wellbore flow is called stabilised if the delta pressure across wellbore is not changing over time.
Reservoir flow is called stabilised if the well productivity index is not changing over time.
It's important to remember the difference between constant rate formation flow and stabilised reservoir flow.
...
On the other hand, the constant rate formation flow may not represent a stabilised formation flow as the bottom-hole pressure and productivity index maybe still in transition after the last rate change.
The WFP methods are not applicable if the well flow is not stabilised even if the flow rate is maintained constant.
There are two special reservoir flow regimes which are both stabilised and maintain constant flow rate: steady state regime (SS) and pseudo-steady state regime (PSS).
...
The pseudo-steady state (PSS) regime is reached when the flow is stabilised with no pressure support at the external boundary.
...
As for formation and bottom-hole pressure in PSS they will be synchronously varying while in SS they will be staying constant.
The table below is summarizing the major differences between SS and PSS regimes.
...
| LaTeX Math Inline | ||
|---|---|---|
|
...
constant
...
constant
...
| LaTeX Math Inline | ||
|---|---|---|
|
...
constant
...
constant
...
...
| LaTeX Math Inline | ||
|---|---|---|
|
...
constant
...
constant
...
| LaTeX Math Inline | ||
|---|---|---|
|
...
constant
...
varying
...
| LaTeX Math Inline | ||
|---|---|---|
|
...
constant
...
varying
It's again important to avoid confusion between the termines stationary conditions (which mean that refered properties are not chaning in time) and stabilised flow conditions which may admit pressure and rate vraition.May refer to Stabilised wellbore flow or Stabilised reservoir flow
See Also
...
Physics / Mechanics / Continuum mechanics / Fluid Mechanics / Fluid Dynamics
...