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  | isbn    = 0891813721

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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>]]

[[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 form layer-cake geometries==

==Shoreface sands form layer-cake geometries==

Shoreface sands prograde by lateral accretion with a tendency to produce layer-cake tabular geometries. Depositional dead ends are rare within individual shoreface sandstones, and sweep efficiencies are generally high as a result; for example, Tyler and Ambrose<ref name=TA1986>Tyler, N., and W. A. Ambrose, 1986, [http://archives.datapages.com/data/bulletns/1986-87/data/pg/0070/0007/0800/0809.htm Facies architecture and production characteristics of strand-plain reservoirs in North Markham-North Bay City field, Frio Formation, Texas]: AAPG Bulletin, v. 70, no. 7, p. 809–829.</ref> described excellent continuity and efficient simple sweep in the Carlson shoreface reservoir of the North Markham-North City Bay field of Texas. The large size and excellent lateral continuity of shoreface reservoirs give a reasonable chance that these systems will be in contact with an aquifer (Table 1):

Shoreface sands prograde by [[lateral]] accretion with a tendency to produce layer-cake tabular geometries. Depositional dead ends are rare within individual shoreface sandstones, and sweep efficiencies are generally high as a result; for example, Tyler and Ambrose<ref name=TA1986>Tyler, N., and W. A. Ambrose, 1986, [http://archives.datapages.com/data/bulletns/1986-87/data/pg/0070/0007/0800/0809.htm Facies architecture and production characteristics of strand-plain reservoirs in North Markham-North Bay City field, Frio Formation, Texas]: AAPG Bulletin, v. 70, no. 7, p. 809–829.</ref> described excellent continuity and efficient simple sweep in the Carlson shoreface reservoir of the North Markham-North City Bay field of Texas. The large size and excellent lateral continuity of shoreface reservoirs give a reasonable chance that these systems will be in contact with an aquifer (Table 1):

{| class="wikitable"

{| class="wikitable"

| Common tidal and fluvial channel fills ||  || Permeability contrast with shore face or barrier island sandstones can result in bypassed oil

| Common tidal and fluvial channel fills ||  || Permeability contrast with shore face or barrier island sandstones can result in bypassed oil

|-

|-

| Lagoonal sandstone bodies (washover fans and flood-tidal deltas) can be wholly or partially enclosed in mudstone ||  || Can form discrete hydraulic units or compartments with bypassed oil

| Lagoonal sandstone bodies (washover fans and flood-tidal deltas) can be wholly or partially enclosed in [[mudstone]] ||  || Can form discrete hydraulic units or compartments with bypassed oil

|}

|}

==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, 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.

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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Shoreface sandstones characteristically show upward-increasing permeability profiles. This in turn reflects increasing grain size and better sorting higher up the shoreface profile (see also [[:File:M91Ch6FG42.JPG|Figures 4]] and [[:File:M91FG108.JPG|5]]). A contrast in rock properties is characteristically seen between the lower and upper shoreface intervals. Upper shoreface beach facies associations generally show higher permeabilities than lower shoreface sediments. When a shoreface sand is subjected to a waterflood, the water tends to edge ahead through the high-permeability tops of these cycles by viscous forces. Gravity and capillary action will then draw the water down through the shoreface cycle into the lower units, displacing oil upward. Sweep efficiencies can be high as a result.

Shoreface sandstones characteristically show upward-increasing permeability profiles. This in turn reflects increasing [[grain size]] and better sorting higher up the shoreface profile (see also [[:File:M91Ch6FG42.JPG|Figures 4]] and [[:File:M91FG108.JPG|5]]). A contrast in rock properties is characteristically seen between the lower and upper shoreface intervals. Upper shoreface beach facies associations generally show higher permeabilities than lower shoreface sediments. When a shoreface sand is subjected to a waterflood, the water tends to edge ahead through the high-permeability tops of these cycles by viscous forces. [[Gravity]] and capillary action will then draw the water down through the shoreface cycle into the lower units, displacing oil upward. Sweep efficiencies can be high as a result.

The degree to which the lower part of the shoreface is swept by water will depend on the magnitude of the vertical permeability within the lower shoreface. In the Middle Jurassic Brent Province of the UK North Sea, bypassed oil is often found within the lower shoreface facies association (Rannoch Formation). The overlying upper shoreface (Etive Formation) is typically an interval of water overrun.<ref>Thomas, J. M. D., and R. Bibby, 1991, The depletion of the Rannoch-Etive sand unit in Brent sands reservoirs in the North Sea, in W. Linville, ed., Reservoir characterization III: Tulsa, PennWell Books, 1008 p.</ref> This behavior can be reinforced by a zone of mica concentration at the top of the lower shoreface, which acts as a baffle to vertical flow (Wetzelaer et al., 1996). Horizontal wells have been drilled in several Brent Province fields to target bypassed oil in the lower shore face.<ref>Braithwaite, C. I. M., J. D. Marshall, and T. C. Holland, 1989, Improving recovery from the Dunlin field, U.K. northern North Sea: Presented at the 54th Annual Technical Conference of the Society of Petroleum Engineers, San Antonio, Texas, SPE Paper 19878, 18 p.</ref><ref>Black, R. C., H. J. Poelen, M. J. Roberts, and S. E. Roddy, 1999, Tern field development: A marriage of new technologies for business benefit, in A. J. Fleet and S. A. R. Boldy, eds., Petroleum geology of northwest Europe: Proceedings of the 5th Conference, Geological Society (London), p. 1063–1073.</ref> The success of these wells depends on the presence of low vertical permeabilities at the top of the lower shoreface interval in order to prevent water coning down from the swept upper shoreface interval.

The degree to which the lower part of the shoreface is swept by water will depend on the magnitude of the vertical permeability within the lower shoreface. In the Middle Jurassic Brent Province of the UK North Sea, bypassed oil is often found within the lower shoreface facies association (Rannoch Formation). The overlying upper shoreface (Etive Formation) is typically an interval of water overrun.<ref>Thomas, J. M. D., and R. Bibby, 1991, The depletion of the Rannoch-Etive sand unit in Brent sands reservoirs in the North Sea, in W. Linville, ed., Reservoir characterization III: Tulsa, PennWell Books, 1008 p.</ref> This behavior can be reinforced by a zone of mica concentration at the top of the lower shoreface, which acts as a baffle to vertical flow (Wetzelaer et al., 1996). Horizontal wells have been drilled in several Brent Province fields to target bypassed oil in the lower shore face.<ref>Braithwaite, C. I. M., J. D. Marshall, and T. C. Holland, 1989, Improving recovery from the Dunlin field, U.K. northern North Sea: Presented at the 54th Annual Technical Conference of the Society of Petroleum Engineers, San Antonio, Texas, SPE Paper 19878, 18 p.</ref><ref>Black, R. C., H. J. Poelen, M. J. Roberts, and S. E. Roddy, 1999, Tern field development: A marriage of new technologies for business benefit, in A. J. Fleet and S. A. R. Boldy, eds., Petroleum geology of northwest Europe: Proceedings of the 5th Conference, Geological Society (London), p. 1063–1073.</ref> The success of these wells depends on the presence of low vertical permeabilities at the top of the lower shoreface interval in order to prevent water coning down from the swept upper shoreface interval.