Changes

===Potentiometric surface===

===Potentiometric surface===

[[file:formation-fluid-pressure-and-its-application_fig5-36.png|300px|thumb|{{figure number|2}}Potentiometric surface for hydrodynamic updip and downdip flow and hydrostatic no flow.]]

[[file:formation-fluid-pressure-and-its-application_fig5-36.png|300px|thumb|{{figure number|2}}Potentiometric surface for hydrodynamic updip and downdip flow and hydrostatic no flow. From Schowalter, 1979; courtesy AAPG.]]

The Potentiometric surface is the surface defined by the hydraulic head (elevation) from a rock unit from several different wells. If the Potentiometrie surface for a given subsurface rock unit is horizontal, then the potential energy of the water in that formation is constant and the water is at rest (hydrostatic). If the Potentiometrie surface is sloping, then the water moves (hydrodynamic) in the direction of the greatest downward slope.<ref name=ch05r11>Hubbert, K., 1953, [http://archives.datapages.com/data/bulletns/1953-56/data/pg/0037/0008/1950/1954.htm Entrapment of petroleum under hydrodynamic conditions]: AAPG Bulletin, vol. 37, no. 8, p. 1954–2026. The original paper that proposed hydrodynamics as an important trapping mechanism.</ref>

The Potentiometric surface is the surface defined by the hydraulic head (elevation) from a rock unit from several different wells. If the Potentiometrie surface for a given subsurface rock unit is horizontal, then the potential energy of the water in that formation is constant and the water is at rest (hydrostatic). If the Potentiometrie surface is sloping, then the water moves (hydrodynamic) in the direction of the greatest downward slope.<ref name=ch05r11>Hubbert, K., 1953, [http://archives.datapages.com/data/bulletns/1953-56/data/pg/0037/0008/1950/1954.htm Entrapment of petroleum under hydrodynamic conditions]: AAPG Bulletin, vol. 37, no. 8, p. 1954–2026. The original paper that proposed hydrodynamics as an important trapping mechanism.</ref>