Mass balance equation

The mass balance equation is an equation that relates densities of a rock with its porosity. The equation is as follows:

$\rho =\phi \rho _{\mathrm {f} }+(1-\phi )\rho _{\mathrm {m} }\$

where $\phi$ is the total porosity, $\rho$ is the measured bulk density, $\rho _{\mathrm {m} }$ is the density of the rock matrix, and $\rho _{\mathrm {f} }$ is the density of the saturating fluid.