Compressibility of a coalbed methane formation

Input(s)

$W_{i}$: Total Volume of Water in the Reservoir (bbl)

$W_{p}$: Total Volume of Water Removed (bbl)

$P_{i}$: Initial Reservoir Pressure (psi)

$P_{d}$: Desorption Pressure (psi)

Output(s)

$c_{t}$: Total Compressibility $(1 / \mathrm{psi})$

Formula(s)

$$ c_{t}=\left(\frac{1}{W_{i}}\right) *\left(\frac{W_{p}}{P_{i}-P_{d}}\right) $$

Reference(s)

Ahmed, T., McKinney, P.D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter:3, Page: 219.