The general form of pressure dynamics (see Universal view of 1D-Radial low-compressibility diffusion):

(1)	$\begin{array}{l}\displaystyle p(t, {\bf r}) = p_i + \frac{qB}{4 \pi \sigma} F \left(\frac{r^2}{4 \chi t} \right)\end{array}$

suggest that isobars

(2)	$\begin{array}{l}\displaystyle p(t, {\bf r}) = p_i + \frac{qB}{4 \pi \sigma} F \left(\frac{r^2}{4 \chi t} \right) = \rm const\end{array}$

will be honouring the following equation:

(3)	$\begin{array}{l}\displaystyle \frac{r^2}{4 \chi t} = \rm const\end{array}$

or

(4)	$\begin{array}{l}\displaystyle r(t) = r_w + 2 \sqrt{\chi t}\end{array}$

which means it will be moving with the phase velocity (see also Formation Pressure Dynamics):

(5)	$\begin{array}{l}\displaystyle u_{p= {\rm const}} = \sqrt{\frac{\chi}{t}}\end{array}$

and slowing down in time.

The practical range for this velocity is around 0.01 m/s which is much higher than actual fluid propagation in typical subsurface reservoirs 3 · 10^-6 m/s (circa 100 metres per year) .

This makes pressure pulsation an effective reservoir scanning technique.

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Pressure Pulse Propagation

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