Reservoir flow with constant total compressibility: 

Not to be confused with Slightly Compressible Fluid since Reservoir flow depends both on Fluid Compressibility  and Pore Compressibility :

c_t = c_r + c_f

and thus can have non-zero compressibility even for incompressible fluids.

It is one of the popular concepts in Pressure Diffusion modelling.

See also

Physics /  Fluid Dynamics / Percolation

[ Slightly Compressible Fluid ] [ Pressure Diffusion @model ]