Changes

[[File:M91FG30.JPG|thumb|300px|{{figure number|7}}Different configurations of oil-water contact are shown. A hydrodynamically tilted oil-water contact results from the movement of water under the oil column. A perched oil-water contact forms where water is locally trapped when the oil migrated into the reservoir.]]

[[File:M91FG30.JPG|thumb|300px|{{figure number|7}}Different configurations of oil-water contact are shown. A hydrodynamically tilted oil-water contact results from the movement of water under the oil column. A perched oil-water contact forms where water is locally trapped when the oil migrated into the reservoir.]]

Some fields have a hydrodynamically tilted oil-water contact ([[:File:M91FG30.JPG|Figure 7]]). This results from variations in aquifer pressure associated with the movement of water in the subsurface, mainly as a result of a mobile artesian aquifer or basin dewatering (Hubbert, 1953). The tilts are toward the direction of reducing pressure and are generally less than 2deg in gradient (Dennis et al., 2000, 2005).

Some fields have a hydrodynamically tilted oil-water contact ([[:File:M91FG30.JPG|Figure 7]]). This results from variations in aquifer pressure associated with the movement of water in the subsurface, mainly as a result of a mobile artesian aquifer or basin dewatering.<ref>Hubbert, M. 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, v. 37, p. 1954–2026.</ref> The tilts are toward the direction of reducing pressure and are generally less than 2deg in gradient (Dennis et al., 2000, 2005).

==Perched oil-water contacts==

==Perched oil-water contacts==