f Production applications of reservoir geochemistry - A current and long term view

Compositional heterogeneties in the fluid columns (oil, gas and water) of petroleum reservoirs are well known and are now believed to be the result of inadequate diffusive and density driven mixing of the columns on a geological time scale. In high quality reservoirs, the length squared-time dependance of diffusive mixing of petroleum column compositional heterogeneities inherited, during filling, from variable maturity and variable source rock facies derived petroleum charges, results generally, (on a say 10 MY limescale) in vertically homogeneous and laterally heterogenolis fluid columns. Similarly density driven advective flow in the reservoir, resulting from inherited netroleum density differences during filling, quickly (<<<1MY) results in Darcy flow mechanically stabilising the reservoir density reservoir distribution.