\phi \cdot \partial_\tau \Psi -   
 \nabla \cdot \left( k \cdot   \vec \nabla \Psi   \right) 
  = 0

-\frac{k}{\mu} \int_{\Sigma} \, \nabla p \, d {\bf A} = q(t)

where

	reservoir pressure		time
	effective porosity		position vector
	total compressibility		gradient operator
	formation permeability to a given fluid		normal surface element of well-reservoir contact
	dynamic viscosity of a given fluid		Pseudo-Pressure
	fluid compressibility factor		Pseudo-Time
			sandface flowrates to/from the well-reservoir contact

See also