...
Pressure difference between the current bottom-hole pressure
and the
bottom-hole pressure at time moment
when flowrate has changed :
| LaTeX Math Block |
|---|
|
\delta p (t) = p_{wf}(t_0) - p_{wf}(t) |
Pressure drop is is:
| | when production rate is increased or injection rate is decreased |
|---|
| | when production rate is decreased or injection rate is increased |
|---|
...
On log-log plots the pressure drop is always pictured as positive (see Fig. 1).
 Image Added
|
Image Removed Image Added
|
Fig. 1. |
A sample typical DTR ( and log-derivative P' in red) presented in log-log plot for PTA type-library analysis
In particular case when the well has been shut-in for a long time and bottom-hole pressure has stabilised by the time moment
and when well is opened for flow the
pressure drop will be equal to
pressure drawdown:
| LaTeX Math Block |
|---|
|
{\rm pressure } \, \, {\rm drop} = \delta p (t) = p_{wf}(t_0) - p_{wf}(t) = p_e - p_{wf}(t) = \Delta p(t) = {\rm pressure } \, \, {\rm drawdown} |
as the initial bottom-hole pressure value
represents
formation pressure :
...
...
...
...
...
See
...
Also
...
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Well Testing / Pressure Testing / Pressure Transient Analysis (PTA) / PTA Diagnostic Plot
[ Well & Reservoir Surveillance ] [ Pressure Diffusion ] [ Pressure drawdown ]Drawdown
