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[[File:M91FG191.JPG|thumb|300px|{{figure number|1}}The photograph shows a shoreface profile on St. Cyrus Beach, Scotland. The beach is just over a hundred meters wide. Reservoir properties are influenced by the degree of wave reworking up the shoreface profile. Lower figure from McCubbin.<ref name=McCubbin>McCubbin, D. G., 1992, [http://archives.datapages.com/data/bulletns/1986-87/data/pg/0070/0007/0800/0809.htm Barrier Islands, strand-plains], in P. A. Scholle and D. R. Spearing, eds., Sandstone depositional environments: [http://store.aapg.org/detail.aspx?id=627 AAPG Memoir 31], p. 247–279.</ref> Reprinted with permission from the AAPG.]]

[[File:M91FG191.JPG|thumb|300px|{{figure number|1}}The photograph shows a shoreface profile on St. Cyrus Beach, Scotland. The beach is just over a hundred meters wide. Reservoir properties are influenced by the degree of wave reworking up the shoreface profile. Lower figure from McCubbin.<ref name=McCubbin>McCubbin, D. G., 1992, [http://archives.datapages.com/data/bulletns/1986-87/data/pg/0070/0007/0800/0809.htm Barrier Islands, strand-plains], in P. A. Scholle and D. R. Spearing, eds., Sandstone depositional environments: [http://store.aapg.org/detail.aspx?id=627 AAPG Memoir 31], p. 247–279.</ref>]]

Shoreface sands are deposited along shorelines, and they generally form extensive, high-quality reservoir systems ([[:File:M91FG191.JPG|Figure 1]]). Wave action and occasional storms act to deposit sand along the shoreface. The lower shoreface lies below fair-weather wave base but can be affected by storms; the sands tend to be siltier and more poorly sorted by comparison to the upper shoreface, where the sands have been subjected to wave winnowing. A shoreface deposit separated by a lagoon from the land is known as a barrier island.

Shoreface sands are deposited along shorelines, and they generally form extensive, high-quality reservoir systems ([[:File:M91FG191.JPG|Figure 1]]). Wave action and occasional storms act to deposit sand along the shoreface. The lower shoreface lies below fair-weather wave base but can be affected by storms; the sands tend to be siltier and more poorly sorted by comparison to the upper shoreface, where the sands have been subjected to wave winnowing. A shoreface deposit separated by a lagoon from the land is known as a barrier island.

==Parasequences and parasequence sets==

==Parasequences and parasequence sets==

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M91Ch11FG73.JPG|{{figure number|2}}Lithofacies map for the upper Piper Sand interval of the Scott field, UK North Sea (from Guscott et al.<ref name=Guscott>Guscott, S., K. Russell, A. Thickpenny, and R. Poddubiuk, 2003, The Scott field, Blocks 15/21a, 15/22, UK North Sea, in J. G. Gluyas and H. M. Hichens, eds., United Kingdom oil and gas fields, commemorative millennium volume: Geological Society (London) Memoir 20, p. 467–481.</ref>). Reprinted with permission from the Geological Society. See also [[Lithofacies maps]]<ref>Shepherd, M., 2009, [http://archives.datapages.com/data/specpubs/memoir91/CHAPTER11/CHAPTER11.HTM Lithofacies maps], in M. Shepherd, Oil field production geology: [http://store.aapg.org/detail.aspx?id=788 AAPG Memoir 91], p. 93-98.

M91Ch11FG73.JPG|{{figure number|2}}Lithofacies map for the upper Piper Sand interval of the Scott field, UK North Sea (from Guscott et al.<ref name=Guscott>Guscott, S., K. Russell, A. Thickpenny, and R. Poddubiuk, 2003, The Scott field, Blocks 15/21a, 15/22, UK North Sea, in J. G. Gluyas and H. M. Hichens, eds., United Kingdom oil and gas fields, commemorative millennium volume: Geological Society (London) Memoir 20, p. 467–481.</ref>). Reprinted with permission from, and &copy; by, the Geological Society. See also [[Lithofacies maps]]<ref>Shepherd, M., 2009, [http://archives.datapages.com/data/specpubs/memoir91/CHAPTER11/CHAPTER11.HTM Lithofacies maps], in M. Shepherd, Oil field production geology: [http://store.aapg.org/detail.aspx?id=788 AAPG Memoir 91], p. 93-98.

M91FG102.JPG|{{figure number|3}}Vertical flow barriers can control the drainage patterns in a reservoir. The degree to which individual barriers are effective across the reservoir can be characterized by vertical flow barrier maps.

M91FG102.JPG|{{figure number|3}}Vertical flow barriers can control the drainage patterns in a reservoir. The degree to which individual barriers are effective across the reservoir can be characterized by vertical flow barrier maps.

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M91Ch6FG42.JPG|{{figure number|4}}Example of a sedimentological core log, Well d-2-C/94a-16, Peejay field, Canada (after Caplan and Moslow).<ref>Caplan, M. L., and T. F. Moslow, 1999, [http://archives.datapages.com/data/bulletns/1999/01jan/0128/0128.htm Depositional origin and facies variability of a Middle Triassic barrier island complex, Peejay field, northeastern British Columbia]: AAPG Bulletin, v. 83, no. 1, p. 128–154.</ref> From Shepherd.<ref>Shepherd, M., 2009, [http://archives.datapages.com/data/specpubs/memoir91/CHAPTER06/CHAPTER06.HTM Sources of data], in M. Shepherd, Oil field production geology: [http://store.aapg.org/detail.aspx?id=788 AAPG Memoir 91], p. 49-63.

M91Ch6FG42.JPG|{{figure number|4}}Example of a sedimentological core log, Well d-2-C/94a-16, Peejay field, Canada (after Caplan and Moslow).<ref>Caplan, M. L., and T. F. Moslow, 1999, [http://archives.datapages.com/data/bulletns/1999/01jan/0128/0128.htm Depositional origin and facies variability of a Middle Triassic barrier island complex, Peejay field, northeastern British Columbia]: AAPG Bulletin, v. 83, no. 1, p. 128–154.</ref> From Shepherd.<ref>Shepherd, M., 2009, [http://archives.datapages.com/data/specpubs/memoir91/CHAPTER06/CHAPTER06.HTM Sources of data], in M. Shepherd, Oil field production geology: [http://store.aapg.org/detail.aspx?id=788 AAPG Memoir 91], p. 49-63.

M91FG108.JPG|{{figure number|5}}The barrier bar-shoreface interval of the Brent Group reservoir in the Thistle field, UK North Sea, shows an upward-increasing permeability profile. This pattern is favorable to a high sweep efficiency (from Williams and Milne).<ref>Williams, R. R., and A. D. Milne, 1991, The Thistle field, Blocks 211/18a and 211/19, UK North Sea, in I. L. Abbots, ed., United Kingdom oil and gas fields, 25 years commemorative volume: Geological Society (London) Memoir 14, p. 199–207.</ref> Reprinted with permission from the Geological Society.

M91FG108.JPG|{{figure number|5}}The barrier bar-shoreface interval of the Brent Group reservoir in the Thistle field, UK North Sea, shows an upward-increasing permeability profile. This pattern is favorable to a high sweep efficiency (from Williams and Milne).<ref>Williams, R. R., and A. D. Milne, 1991, The Thistle field, Blocks 211/18a and 211/19, UK North Sea, in I. L. Abbots, ed., United Kingdom oil and gas fields, 25 years commemorative volume: Geological Society (London) Memoir 14, p. 199–207.</ref> Reprinted with permission from, and &copy; by, the Geological Society.

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==Beach sandstones==

==Beach sandstones==

[[File:M91FG117.JPG|thumb|300px|{{figure number|6}}Time series of water cut maps from the West Cornelius reservoir, North Markham-North Bay City field, Texas. In this strand-plain reservoir, east-northeastndashwest-southwest-oriented beach ridge macroforms are fairways for water ingress. Tidal mud flat deposits south of the field restrict water influx from this direction (from Tyler and Ambrose, reprinted with permission from the AAPG.<ref name=TA1986 />)]]

[[File:M91FG117.JPG|thumb|300px|{{figure number|6}}Time series of water cut maps from the West Cornelius reservoir, North Markham-North Bay City field, Texas. In this strand-plain reservoir, east-northeastndashwest-southwest-oriented beach ridge macroforms are fairways for water ingress. Tidal mud flat deposits south of the field restrict water influx from this direction (from Tyler and Ambrose.<ref name=TA1986 />)]]

Beach sandstones form as single belts or accrete laterally to form strand plains many kilometers long and several kilometers wide. Modern strand plains such as the Nayarit strand plain of western Mexico show a ridge and swale topography on their surfaces.<ref name=McCubbin /> Mud fills in the interridge swales can act as permeability barriers to lateral flow in the subsurface. One example in the Frio Formation of south Texas is known to have caused the compartmentalization of a beach ridge interval containing several million barrels of recoverable oil.<ref>Reistroffer, J. R., and N. Tyler, 1991, Depositional environments and reservoir compartmentalization within the Frio zone 21-B reservoir, Tijerina-Canales-Blucher field, South Texas (abs.): Transactions of the Gulf Coast Association of Geological Societies, v. 41, p. 559–560.</ref> Water ingress may preferentially occur along the low-lying swales<ref name=TA1986 /> ([[:File:M91FG117.JPG|Figure 6]]).

Beach sandstones form as single belts or accrete laterally to form strand plains many kilometers long and several kilometers wide. Modern strand plains such as the Nayarit strand plain of western Mexico show a ridge and swale topography on their surfaces.<ref name=McCubbin /> Mud fills in the interridge swales can act as permeability barriers to lateral flow in the subsurface. One example in the Frio Formation of south Texas is known to have caused the compartmentalization of a beach ridge interval containing several million barrels of recoverable oil.<ref>Reistroffer, J. R., and N. Tyler, 1991, Depositional environments and reservoir compartmentalization within the Frio zone 21-B reservoir, Tijerina-Canales-Blucher field, South Texas (abs.): Transactions of the Gulf Coast Association of Geological Societies, v. 41, p. 559–560.</ref> Water ingress may preferentially occur along the low-lying swales<ref name=TA1986 /> ([[:File:M91FG117.JPG|Figure 6]]).