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Line 198: + + − − [[file:M91FG190.JPG|thumb|300px|{{figure number|9}}Sweep patterns in delta sediments. (a) Preferential water ingress along channel sediments can result in bypassed oil in the surrounding sediments. From the South Pass Block 27 field, offshore Louisiana (from Hartman and Paynter<ref name=Hartmanandpaynter_1979>Hartman, J. A., and D. D. Paynter, 1979, Drainage anomalies in Gulf Coast Tertiary sandstones: Journal of Petroleum Technology, [https://www.onepetro.org/journal-paper/SPE-7532-PA SPE Paper 7532], v. 31, no. 10, p. 1313–1322.</ref>). Reprinted with permission from, and © by, the Society of Petroleum Engineers. (b) Horizontal well drilled to target oil within a mouth bar in the Ivishak Formation, [[Prudhoe Bay field]]. Bay shales above the mouth bar act to prevent gas ingress from a gas cap immediately above (from Tye et al.<ref name=Tyeetal_1999 />).]]
→Sweep patterns in distributary channels
==Sweep patterns in distributary channels==
==Sweep patterns in distributary channels==
[[file:M91FG190.JPG|thumb|300px|{{figure number|9}}Sweep patterns in delta sediments. (a) Preferential water ingress along channel sediments can result in bypassed oil in the surrounding sediments. From the South Pass Block 27 field, offshore Louisiana (from Hartman and Paynter<ref name=Hartmanandpaynter_1979>Hartman, J. A., and D. D. Paynter, 1979, Drainage anomalies in Gulf Coast Tertiary sandstones: Journal of Petroleum Technology, [https://www.onepetro.org/journal-paper/SPE-7532-PA SPE Paper 7532], v. 31, no. 10, p. 1313–1322.</ref>). Reprinted with permission from, and © by, the Society of Petroleum Engineers. (b) Horizontal well drilled to target oil within a mouth bar in the Ivishak Formation, [[Prudhoe Bay field]]. Bay shales above the mouth bar act to prevent gas ingress from a gas cap immediately above (from Tye et al.<ref name=Tyeetal_1999 />).]]
[[Distributary channel]]s tend to be narrow with a common width range of 10–300 m (33–984 ft).<ref name=Gibling_2006 /> It is possible that hydrocarbons in isolated distributary channels may be missed in fields with larger well spacings. Richardson et al.<ref name=Richardsonetal_1989 /> stated that it could be impractical to try and locate both injection and production wells to sweep individual distributary channels. The sweep efficiency in the distributary channels will be low without direct injection support, particularly if the sand bodies are isolated. There is a better chance of improving recovery by waterflooding the delta-front sandstones.
[[Distributary channel]]s tend to be narrow with a common width range of 10–300 m (33–984 ft).<ref name=Gibling_2006 /> It is possible that hydrocarbons in isolated distributary channels may be missed in fields with larger well spacings. Richardson et al.<ref name=Richardsonetal_1989 /> stated that it could be impractical to try and locate both injection and production wells to sweep individual distributary channels. The sweep efficiency in the distributary channels will be low without direct injection support, particularly if the sand bodies are isolated. There is a better chance of improving recovery by waterflooding the delta-front sandstones.
==Sweep patters in delta-front sediments==
==Sweep patters in delta-front sediments==