@wikipedia

A measure of rock volume change due to pressure  $//<![CDATA[ \begin{array}{l}p\end{array} //]]>$ variation:

It stays constant for small pressure variations ( $//<![CDATA[ \begin{array}{l}c_r(p) = \rm const\end{array} //]]>$) but for a wide range pressure variations the dependence on ambient pressure  $//<![CDATA[ \begin{array}{l}c_r(p)\end{array} //]]>$ can not be neglected

The typical values are in  $//<![CDATA[ \begin{array}{l}0.5 \div 1.5 \cdot 10^{-6} \, {\rm kPa}^{-1}\end{array} //]]>$ but may go higher for poorly consolidated rocks.

See also

Petroleum Industry / Upstream / Subsurface E&P Disciplines / Rock Geomechanics

[ Basic reservoir properties ]

[ Pore Compressibility ( cϕ ) ]