Pressure Pulse Testing

Borehole (Downhole or THP) pressure survey based on the pressure response to the periodic flow rate variations (also called "cycles" or "pulses" ).

The usual practise is to create 3 - 5 pulses.

The pressure response is recorded in

the same well where the flowrate is varying ( and in this case is called Self-Pulse Test)

or

in the offset well (an in this case is called Pressure Pulse Interference Test)

In case of harmonic pulsations and sufficiently long pressure-rate delay and a simple diffusion model (single-bed homogeneous reservoir without boundary) the test data can be approximated by analytical model:

$\begin{array}{l}\displaystyle q=q_0 \cdot \cos \left(\frac{2 \pi \, t}{T} \right)\end{array}$

$\begin{array}{l}\displaystyle p=p_0 \cdot \cos \left(\frac{2 \pi \, t}{T} + \delta \right)\end{array}$

where

$\begin{array}{l}\displaystyle \delta = \frac{\pi}{8} + \frac{L}{\sqrt{\chi \, T}}\end{array}$

phase shift related to the pressure response delay to the flowrate variation

$\begin{array}{l}\displaystyle p_0 = \frac{q_0}{\sigma} ...\end{array}$

pressure response to the flowrate variation

$\begin{array}{l}\displaystyle \sigma = \left< \frac{k}{\mu} \right> h\end{array}$

transmissbility

$\begin{array}{l}\displaystyle \chi = \left< \frac{k}{\mu} \right> \frac{1}{c_t \, \phi}\end{array}$

pressure diffusivity

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Pressure Pulse Testing