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.<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).

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.<ref>Dennis, H., J. Baillie, T. Holt, and D. Wessel-Berg, 2000, Hydrodynamic activity and tilted oil-water contacts in the North Sea, in K. Ofstad, E. J. Kittilsen, and P. Alexander-Marrack, eds., Improving the exploration process by learning from the past: Norwegian Petroleum Society Special Publication 9, p. 171–185.</ref><ref>Dennis, H., P. Bergmo, and T. Holt, 2005, Tilted oil-water contacts: Modelling the effects of aquifer heterogeneity, in A. G. Dore and B. A. Vining, eds., Petroleum geology: Northwest Europe and global perspectives: Proceedings of the 6th Petroleum Geology Conference, Geological Society (London), v. 1, p. 145–158.</ref>

==Perched oil-water contacts==

==Perched oil-water contacts==