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Three-dimensional modeling of clinoforms in shallow-marine reservoirs (view source)

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Key factors influencing fluid flow and reservoir behavior include facies architecture and heterogeneity distribution conditioned to stratal surfaces. Within shallow-marine reservoirs, clinoforms are one such type of stratal surface. Clinoforms are dipping surfaces having geometry that preserves the depositional morphology of the delta-front or shoreface slope; and their distribution reflects the progradation history of the shoreline<ref>Barrell, J., 1912, Criteria for the recognition of ancient delta deposits: Geological Society of America Bulletin, v. 23, no. 1, p. 377–446, doi: 10.1130/GSAB-23-377.</ref><ref>Rich, J. L., 1951, Three critical environments of deposition, and criteria for recognition of rocks deposited in each of them: Geological Society of America Bulletin, v. 62, no. 1, p. 1–20, doi: 10.1130/0016-7606(1951)62[1:TCEODA]2.0.CO;2.</ref><ref name=GB05>Gani, M. R., and J. P. Bhattacharya, 2005, Lithostratigraphy versus chronostratigraphy in facies correlations of Quaternary deltas: Application of bedding correlation, inL. Giosan, and J. P. Bhattacharya, eds., River deltas—Concepts, models and examples: SEPM Special Publication 83, p. 31–47.</ref><ref name=Sch09>Sech, R. P., M. D. Jackson, and G. J. Hampson, 2009, [http://archives.datapages.com/data/bulletns/2009/09sep/BLTN08144/BLTN08144.HTM Three-dimensional modeling of a shoreface-shelf parasequence reservoir analog: Part 1. Surface-based modeling to capture high resolution facies architecture]: AAPG Bulletin, v. 93, no. 9, p. 1155–1181, doi: 10.1306/05110908144.</ref> ([[:File:BLTN13190fig1.jpg|Figure 1]]). Clinoforms control aspects of detailed facies architecture within parasequences and can also act as low-permeability barriers or baffles to flow.<ref name=WB96>Wehr, F. L., and L. D. Brasher, 1996, Impact of sequence-based correlation style on reservoir model behaviour, lower Brent Group, North Cormorant field, UK North Sea, inJ. A. Howell, and J. A. Aitken, eds., High resolution sequence stratigraphy: Innovations and applications: Geological Society, London, Special Publication 104, p. 115–128.</ref><ref name=Answrth1999>Ainsworth, B. R., M. Sanlung, and S. T. C. Duivenvoorden, 1999, [http://archives.datapages.com/data/bulletns/1999/10oct/1535/1535.htm Correlation techniques, perforation strategies, and recovery factors: An integrated 3-D reservoir modeling study, Sirikit field, Thailand]: AAPG Bulletin, v. 83, p. 1535–1551.</ref><ref>Dutton, S. P., B. J. Willis, C. D. White, and J. P. Bhattacharya, 2000, Outcrop characterization of reservoir quality and interwell-scale cement distribution in a tide-influenced delta, Frontier Formation, Wyoming USA: Clay Minerals, v. 35, no. 1, p. 95–105, doi: 10.1180/000985500546756.</ref><ref name=Hwll2008a>Howell, J. A., A. Skorstad, A. MacDonald, A. Fordham, S. Flint, B. Fjellvoll, and T. Manzocchi, 2008a, Sedimentological parameterization of shallow-marine reservoirs: Petroleum Geoscience, v. 14, no. 1, p. 17–34, doi: 10.1144/1354-079307-787.</ref><ref name=Hwll2008b>Howell, J. A., Å. Vassel, and T. Aune, 2008b, Modelling of dipping clinoform barriers within deltaic outcrop analogues from the Cretaceous Western Interior Basin, U.S.A., inA. Robinson, P. Griffiths, S. Price, J. Hegre, and A. H. Muggeridge, eds., The future of geologic modelling in hydrocarbon development: Geological Society, London, Special Publication 309, p. 99–121.</ref><ref name=Jckson2009>Jackson, M. D., G. J. Hampson, and R. P. Sech, 2009, [http://archives.datapages.com/data/bulletns/2009/09sep/BLTN08145/BLTN08145.HTM Three-dimensional modeling of a shoreface-shelf parasequence reservoir analog: Part 2. Geological controls on fluid flow and hydrocarbon production]: AAPG Bulletin, v. 93, no. 9, p. 1183–1208, doi: 10.1306/05110908145.</ref><ref name=EH2010>Enge, H. D., and J. A. Howell, 2010, [http://archives.datapages.com/data/bulletns/2010/02feb/BLTN08112/BLTN08112.HTM Impact of deltaic clinothems on reservoir performance: Dynamic studies of reservoir analogs from the Ferron Sandstone Member and Panther Tongue, Utah]: AAPG Bulletin, v. 94, no. 2, p. 139–161, doi: 10.1306/07060908112.</ref> Therefore, it is important to include clinoforms in models of shallow-marine reservoirs to properly characterize facies architecture and volumes of hydrocarbons in place.<ref name=Sch09 /> Under certain displacement conditions and if the clinoforms are associated with significant barriers to flow, clinoforms must be included in dynamic simulations to accurately predict likely drainage patterns and ultimate recovery of hydrocarbons.<ref name=Jckson2009 />

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Standard modeling techniques are not well suited to capturing clinoforms, particularly if they are numerous, below seismic resolution, and/or difficult to correlate between wells. Few studies have attempted to identify and correlate clinoforms in the subsurface<ref>Livera, S. E., and B. Caline, 1990, The sedimentology of the Brent Group in the Cormorant Block IV oil field: Journal of Petroleum Geology, v. 13, no. 4, p. 367–396, doi: 10.1111/j.1747-5457.1990.tb00855.x.</ref><ref>Jennette, D. C., and C. O. Riley, 1996, Influence of relative sea level on facies and reservoir geometry of the Middle Jurassic Lower Brent Group, UK North Viking Graben, inJ. A. Howell, and J. F. Aitken, eds., High-resolution sequence stratigraphy: Innovations and applications: Geological Society, London, Special Publication 104, p. 87–113.</ref><ref>Løseth, T. M., and A. Ryseth, 2003, A depositional model and sequence stratigraphic model for the Rannoch and Etive formations, Oseberg field, northern North Sea: Norwegian Journal of Geology, v. 83, p. 87–106.</ref><ref>Matthews, S., A. D. Thurlow, F. J. Aitken, S. Gowland, P. D. Jones, G. J. Colville, C. I. Robinson, and A. M. Taylor, 2005, A late life opportunity: Using a multidisciplinary approach to unlock reserves in the Rannoch Formation, Ninian field, inA. G. Doré, and B. A. Vining, eds., Petroleum geology: Northwest Europe and global perspective: Proceedings of the 6th Conference of the Geological Society (London), p. 496–510.</ref><ref name=Hmpsn2008>Hampson, G. J., A. B. Rodriguez, J. E. A. Storms, H. D. Johnson, and C. T. Meyer, 2008, Geomorphology and high-resolution stratigraphy of progradational wave-dominated shoreline deposits: Impact on reservoir-scale facies architecture, ~~inG~~. J. Hampson, R. J. Steel, P. M. Burgess, and R. W. Dalrymple, eds., Recent advances in models of siliclastic shallow-marine stratigraphy: SEPM Special Publication 90, p. 117–142.</ref> or have built two-dimensional (2-D)<ref name=WB96 /><ref name=Frstr2004>Forster, C. B., S. H. Snelgrove, and J. V. Koebbe, 2004, [http://archives.datapages.com/data/specpubs/study50/sg50ch14/sg50ch14.htm Modelling permeability structure and simulating fluid flow in a reservoir analog: Ferron Sandstone, Ivie Creek area, east-central Utah], in T. C. Chidsey, Jr., R. D. Adams, and T. H. Morris, eds., Regional to wellbore analog for fluvial-deltaic reservoir modeling: The Ferron Sandstone of Utah: [http://store.aapg.org/detail.aspx?id=655 AAPG Studies in Geology 50], p. 359–382.</ref> or three-dimensional (3-D)<ref name=Hwll2008a /><ref name=Hwll2008b /><ref name=Jckson2009 /><ref name=Sch09 /><ref name=EH2010 /> flow simulation models that incorporate clinoforms. Previous studies of the Ferron Sandstone Member have incorporated simple clinoform geometries into reservoir models by using either object-based<ref name=Hwll2008b /> or deterministic<ref name=Hwll2008a /> approaches. Enge and Howell<ref name=EH2010 /> used data collected by light detection and ranging (LIDAR) equipment to precisely recreate 3-D clinoform geometries from part of the Ferron Sandstone Member outcrops; the resulting flow-simulation model contained deterministically modeled clinoforms but in a volume smaller than most reservoirs (500 × 500 × 25 m [1640 × 1640 × 82 ft]). Sech et al.<ref name=Sch09 /> used a surface-based modeling approach to produce a deterministic, 3-D model of a wave-dominated shoreface–shelf parasequence from a rich, high-resolution outcrop data set (Cretaceous Kenilworth Member, Utah), and Jackson et al.<ref name=Jckson2009 /> used this model to investigate the impact of clinoforms on fluid flow. Jackson et al.<ref name=Jckson2009 /> and Enge and Howell<ref name=EH2010 /> both showed that capturing numerous clinoforms in fluid-flow simulations is feasible. Process-based forward numerical models are capable of generating geologically realistic, 3-D stratigraphic architectures containing clinoforms in shallow-marine strata (e.g., Edmonds and Slingerland;<ref name=ES2010>Edmonds, D. A., and R. L. Slingerland, 2010, Significant effect of sediment cohesion on delta morphology: Nature Geoscience, v. 3, no. 2, p. 105–109, doi: 10.1038/ngeo730.</ref> Geleynse et al.<ref name=Glnyse>Geleynse, N. L., J. E. A. Storms, D. J. R. Walstra, H. R. A. Jagers, Z. B. Wang, and M. J. F. Sive, 2011, Controls on river delta formation; insights from numerical modeling: Earth and Planetary Science Letters, v. 302, no. 1–2, p. 217–226, doi: 10.1016/j.epsl.2010.12.013.</ref>), but it can be difficult to replicate geometries observed in outcrop data, or condition models to subsurface data (e.g., Charvin et al.<ref>Charvin, K., G. J. Hampson, K. L. Gallagher, and R. Labourdette, 2009, A Bayesian approach to inverse modelling of stratigraphy, Part 2: Validation tests: Basin Research, v. 21, no. 1, p. 27–45, doi: 10.1111/j.1365-2117.2008.00370.x.</ref>); consequently, process-based approaches have yet to be developed for routine use in reservoir modeling.

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Standard modeling techniques are not well suited to capturing clinoforms, particularly if they are numerous, below seismic resolution, and/or difficult to correlate between wells. Few studies have attempted to identify and correlate clinoforms in the subsurface<ref>Livera, S. E., and B. Caline, 1990, The sedimentology of the Brent Group in the Cormorant Block IV oil field: Journal of Petroleum Geology, v. 13, no. 4, p. 367–396, doi: 10.1111/j.1747-5457.1990.tb00855.x.</ref><ref>Jennette, D. C., and C. O. Riley, 1996, Influence of relative sea level on facies and reservoir geometry of the Middle Jurassic Lower Brent Group, UK North Viking Graben, inJ. A. Howell, and J. F. Aitken, eds., High-resolution sequence stratigraphy: Innovations and applications: Geological Society, London, Special Publication 104, p. 87–113.</ref><ref>Løseth, T. M., and A. Ryseth, 2003, A depositional model and sequence stratigraphic model for the Rannoch and Etive formations, Oseberg field, northern North Sea: Norwegian Journal of Geology, v. 83, p. 87–106.</ref><ref>Matthews, S., A. D. Thurlow, F. J. Aitken, S. Gowland, P. D. Jones, G. J. Colville, C. I. Robinson, and A. M. Taylor, 2005, A late life opportunity: Using a multidisciplinary approach to unlock reserves in the Rannoch Formation, Ninian field, inA. G. Doré, and B. A. Vining, eds., Petroleum geology: Northwest Europe and global perspective: Proceedings of the 6th Conference of the Geological Society (London), p. 496–510.</ref><ref name=Hmpsn2008>Hampson, G. J., A. B. Rodriguez, J. E. A. Storms, H. D. Johnson, and C. T. Meyer, 2008, Geomorphology and high-resolution stratigraphy of progradational wave-dominated shoreline deposits: Impact on reservoir-scale facies architecture, in G. J. Hampson, R. J. Steel, P. M. Burgess, and R. W. Dalrymple, eds., Recent advances in models of siliclastic shallow-marine stratigraphy: SEPM Special Publication 90, p. 117–142.</ref> or have built two-dimensional (2-D)<ref name=WB96 /><ref name=Frstr2004>Forster, C. B., S. H. Snelgrove, and J. V. Koebbe, 2004, [http://archives.datapages.com/data/specpubs/study50/sg50ch14/sg50ch14.htm Modelling permeability structure and simulating fluid flow in a reservoir analog: Ferron Sandstone, Ivie Creek area, east-central Utah], in T. C. Chidsey, Jr., R. D. Adams, and T. H. Morris, eds., Regional to wellbore analog for fluvial-deltaic reservoir modeling: The Ferron Sandstone of Utah: [http://store.aapg.org/detail.aspx?id=655 AAPG Studies in Geology 50], p. 359–382.</ref> or three-dimensional (3-D)<ref name=Hwll2008a /><ref name=Hwll2008b /><ref name=Jckson2009 /><ref name=Sch09 /><ref name=EH2010 /> flow simulation models that incorporate clinoforms. Previous studies of the Ferron Sandstone Member have incorporated simple clinoform geometries into reservoir models by using either object-based<ref name=Hwll2008b /> or deterministic<ref name=Hwll2008a /> approaches. Enge and Howell<ref name=EH2010 /> used data collected by light detection and ranging (LIDAR) equipment to precisely recreate 3-D clinoform geometries from part of the Ferron Sandstone Member outcrops; the resulting flow-simulation model contained deterministically modeled clinoforms but in a volume smaller than most reservoirs (500 × 500 × 25 m [1640 × 1640 × 82 ft]). Sech et al.<ref name=Sch09 /> used a surface-based modeling approach to produce a deterministic, 3-D model of a wave-dominated shoreface–shelf parasequence from a rich, high-resolution outcrop data set (Cretaceous Kenilworth Member, Utah), and Jackson et al.<ref name=Jckson2009 /> used this model to investigate the impact of clinoforms on fluid flow. Jackson et al.<ref name=Jckson2009 /> and Enge and Howell<ref name=EH2010 /> both showed that capturing numerous clinoforms in fluid-flow simulations is feasible. Process-based forward numerical models are capable of generating geologically realistic, 3-D stratigraphic architectures containing clinoforms in shallow-marine strata (e.g., Edmonds and Slingerland;<ref name=ES2010>Edmonds, D. A., and R. L. Slingerland, 2010, Significant effect of sediment cohesion on delta morphology: Nature Geoscience, v. 3, no. 2, p. 105–109, doi: 10.1038/ngeo730.</ref> Geleynse et al.<ref name=Glnyse>Geleynse, N. L., J. E. A. Storms, D. J. R. Walstra, H. R. A. Jagers, Z. B. Wang, and M. J. F. Sive, 2011, Controls on river delta formation; insights from numerical modeling: Earth and Planetary Science Letters, v. 302, no. 1–2, p. 217–226, doi: 10.1016/j.epsl.2010.12.013.</ref>), but it can be difficult to replicate geometries observed in outcrop data, or condition models to subsurface data (e.g., Charvin et al.<ref>Charvin, K., G. J. Hampson, K. L. Gallagher, and R. Labourdette, 2009, A Bayesian approach to inverse modelling of stratigraphy, Part 2: Validation tests: Basin Research, v. 21, no. 1, p. 27–45, doi: 10.1111/j.1365-2117.2008.00370.x.</ref>); consequently, process-based approaches have yet to be developed for routine use in reservoir modeling.

Deterministic approaches are appropriate for modeling clinoforms that are tightly constrained by outcrop data, but they are time consuming to implement. Moreover, they do not allow flexibility in conditioning clinoform geometry and distribution to sparser data sets with a larger degree of uncertainty, such as those that are typically available for subsurface reservoirs. Incorporating hundreds of deterministic clinoform surfaces within a field-scale reservoir model would be a dauntingly time-consuming task, particularly if multiple scenarios and realizations that capture uncertainty in clinoform geometry and distribution are to be modeled. A stochastic, 3-D, surface-based modeling approach is required to address these issues. Similar approaches have been demonstrated for other depositional environments (e.g., Xie et al.;<ref>Xie, Y., A. S. Cullick, and C. V. Deutsch, 2001, Surface geometry and trend modeling for integration of stratigraphic data in reservoir models: SPE Paper 68817, 13 p.</ref> Pyrcz et al.;<ref>Pyrcz, M. J., O. Catuneanu, and C. V. Deutsch, 2005, [http://archives.datapages.com/data/bulletns/2005/02feb/0177/0177.HTM Stochastic surface-based modeling of turbidite lobes]: AAPG Bulletin, v. 89, no. 2, p. 177–191, doi: 10.1306/09220403112.</ref> Zhang et al.<ref>Zhang, X., M. J. Pyrcz, and C. V. Deutsch, 2009, Stochastic surface modeling of deepwater depositional systems for improved reservoir models: Journal of Petroleum Science and Engineering, v. 68, no. 1–2, p. 118–134, doi: 10.1016/j.petrol.2009.06.019.</ref>) and to create models of generic, dipping barriers to flow (e.g., Jackson and Muggeridge<ref>Jackson, M. D., and A. H. Muggeridge, 2000, The effect of discontinuous shales on reservoir performance during immiscible flow: SPE Journal, v. 5, no. 4, p. 446–455, doi: 10.2118/69751-PA.</ref>), but at present, there are no tools available to automate the generation of multiple 3-D clinoforms using a small number of parameters. The aims of this paper are to develop an efficient, quick, and practical method for incorporating clinoforms into models of shallow-marine reservoirs and to validate its application through building both geologic and fluid-flow simulation models.

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===Cross-Sectional Clinoform Geometry===

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The shape and dip angle of a deltaic or shoreface clinoform in cross section is a function of modal grain size, proportion of mud, and the depositional process regime at the shoreline. In sandy, fluvial-dominated deltas, clinoforms have simple concave-upward geometries and steep dip angles (up to 15°)<ref name=GB05 /> (e.g., [[:File:BLTN13190fig1.jpg|Figure 1]]). Similar geometries have been documented in sandy, tide-influenced deltas (dip angles up to 5°–15°).<ref name=Wllsetal1999>Willis, B. J., J. P. Bhattacharya, S. L. Gabel, and C. D. White, 1999, Architecture of a tide-influenced river delta in the Frontier Formation of central Wyoming, USA: Sedimentology, v. 46, no. 4, p. 667–688, doi: 10.1046/j.1365-3091.1999.00239.x.</ref> Concave-upward clinoform geometry is also typical of sandy, wave-dominated deltas and strandplains, although the clinoforms have smaller dip angles (typically up to 1°–2°).<ref>Hampson, G. J., and J. E. A. Storms, 2003, Geomorphological and sequence stratigraphic variability in wave-dominated shoreface-shelf parasequences: Sedimentology, v. 50, no. 4, p. 667–701, doi: 10.1046/j.1365-3091.2003.00570.x.</ref><ref name=GB05 /> Clinoforms are consistently inclined paleobasinward down depositional dip; and, along depositional strike, they exhibit bidirectional, concave-upward dips if the delta-front was lobate in plan view (e.g., Willis et al.;<ref name=Wllsetal1999 /> Kolla et al.;<ref name=Kll>Kolla, V., P. Biondi, B. Long, and R. Fillon, 2000, Sequence stratigraphy and architecture of the late Pleistocene Lagniappe delta complex, northeast Gulf of Mexico, inD. Hunt, and R. L. Gawthorpe, eds., Sedimentary responses to forced regressions: Geological Society, London, Special Publication 172, p. 291–327.</ref> Roberts et al.<ref name=Rbrts2004 />) or appear horizontal if the shoreline was approximately linear (e.g., Hampson~~, 2000~~). Clinoforms are usually truncated at their tops by a variety of channelized erosion surfaces formed during shoreline advance (e.g., distributary channels, incised valleys) and by channelized and/or planar transgressive erosion surfaces (tide and wave ravinement surfaces ~~sensu~~ Swift, 1968) associated with shoreline retreat. Consequently, most sandy shoreline clinoforms lack a decrease in depositional dip (rollover) near their tops, although this geometry is ubiquitous in larger, shelf-slope margin clinoforms (e.g., Steckler et al., 1999) and in the outer, muddy portion of compound deltaic clinoforms with a broad subaqueous topset that lies seaward of the shoreline (e.g., Pirmez et al., 1998).

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The shape and dip angle of a deltaic or shoreface clinoform in cross section is a function of modal grain size, proportion of mud, and the depositional process regime at the shoreline. In sandy, fluvial-dominated deltas, clinoforms have simple concave-upward geometries and steep dip angles (up to 15°)<ref name=GB05 /> (e.g., [[:File:BLTN13190fig1.jpg|Figure 1]]). Similar geometries have been documented in sandy, tide-influenced deltas (dip angles up to 5°–15°).<ref name=Wllsetal1999>Willis, B. J., J. P. Bhattacharya, S. L. Gabel, and C. D. White, 1999, Architecture of a tide-influenced river delta in the Frontier Formation of central Wyoming, USA: Sedimentology, v. 46, no. 4, p. 667–688, doi: 10.1046/j.1365-3091.1999.00239.x.</ref> Concave-upward clinoform geometry is also typical of sandy, wave-dominated deltas and strandplains, although the clinoforms have smaller dip angles (typically up to 1°–2°).<ref>Hampson, G. J., and J. E. A. Storms, 2003, Geomorphological and sequence stratigraphic variability in wave-dominated shoreface-shelf parasequences: Sedimentology, v. 50, no. 4, p. 667–701, doi: 10.1046/j.1365-3091.2003.00570.x.</ref><ref name=GB05 /> Clinoforms are consistently inclined paleobasinward down depositional dip; and, along depositional strike, they exhibit bidirectional, concave-upward dips if the delta-front was lobate in plan view (e.g., Willis et al.;<ref name=Wllsetal1999 /> Kolla et al.;<ref name=Kll>Kolla, V., P. Biondi, B. Long, and R. Fillon, 2000, Sequence stratigraphy and architecture of the late Pleistocene Lagniappe delta complex, northeast Gulf of Mexico, inD. Hunt, and R. L. Gawthorpe, eds., Sedimentary responses to forced regressions: Geological Society, London, Special Publication 172, p. 291–327.</ref> Roberts et al.<ref name=Rbrts2004 />) or appear horizontal if the shoreline was approximately linear (e.g., Hampson<ref name=Hmpsn2000 />). Clinoforms are usually truncated at their tops by a variety of channelized erosion surfaces formed during shoreline advance (e.g., distributary channels, incised valleys) and by channelized and/or planar transgressive erosion surfaces (tide and wave ravinement surfaces sense Swift<ref>Swift, D. J., 1968, Coastal erosion and transgressive stratigraphy: Journal of Geology, v. 76, no. 4, p. 444–456, doi: 10.1086/jg.1968.76.issue-4.</ref>) associated with shoreline retreat. Consequently, most sandy shoreline clinoforms lack a decrease in depositional dip (rollover) near their tops, although this geometry is ubiquitous in larger, shelf-slope margin clinoforms (e.g., Steckler et al.<ref name=Stcklr1999>Steckler, M. S., G. S. Mountain, K. G. Miller, and N. Christie-Blick, 1999, Reconstruction of tertiary progradation and clinoform development on the New Jersey passive margin by 2D backstripping: Marine Geology, v. 154, no. 1–4, p. 399–420, doi: 10.1016/S0025-3227(98)00126-1.</ref>) and in the outer, muddy portion of compound deltaic clinoforms with a broad subaqueous topset that lies seaward of the shoreline (e.g., Pirmez et al.<ref>Pirmez, C., L. F. Pratson, and M. S. Steckler, 1998, Clinoform development by advection-diffusion of suspended sediment; modeling and comparison to natural systems: Journal of Geophysical Research B: Solid Earth and Planets, v. 103, p. 24,141–24,157, doi: 10.1029/98JB01516.</ref>).

Here, a geometric approach is used to represent the depositional dip cross-section shape of a clinoform with a dimensionless shape function, ''s(rc)'' ([[:File:BLTN13190fig2.jpg|Figure 2E]]), such as a power law for concave-upward, sandy, shoreline clinoforms:

:<math>s(r_c) = \left ( \frac{(r_{\text{max}}(x, y) - r_c(x, y))^P}{r_{\text{max}}(x, y) - r_{\text{min}}(x, y))^P} \right )</math>

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However, as the algorithm is generic, the mathematical expression of the dimensionless shape function is interchangeable so that other clinoform geometries can be represented; for example, a sigmoid function can be used to represent clinoforms in a larger, shelf-slope margin settings (e.g., Steckler et al.~~, 1999~~). By combining the height function (equation 1), with the shape function (equation 7), the clinoform shape function, ''c(rc)'', is used to construct the shape of a clinoform surface:

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However, as the algorithm is generic, the mathematical expression of the dimensionless shape function is interchangeable so that other clinoform geometries can be represented; for example, a sigmoid function can be used to represent clinoforms in a larger, shelf-slope margin settings (e.g., Steckler et al.<ref name=Stcklr1999 />). By combining the height function (equation 1), with the shape function (equation 7), the clinoform shape function, ''c(rc)'', is used to construct the shape of a clinoform surface:

:<math>c(r_c) = h_{\text{min}}(r_c) + \left ( \frac{(r_{\text{max}}(x, y) - r_c(x, y))^P}{r_{\text{max}}(x, y) - r_{\text{min}}(x, y))^P} h(r_c) \right )</math>

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Reservoir zones in the Troll West accumulation are defined by alternating layers of fine-grained, micaceous sandstone and coarse-grained sandstone (informally referred to as m sands and c sands, respectively). The coarse-grained sandstones have higher porosity and permeability (hundreds to thousands of millidarcys) than the fine-grained, micaceous sandstones (tens to hundreds of millidarcys) (Gibbons et al., 1993; Dreyer et al., 2005). Each couplet of fine-grained, micaceous sandstone and overlying coarse-grained sandstones corresponds to the lower and upper part of a single delta-front parasequence (Dreyer et al., 2005). The 3-D seismic data image laterally extensive (up to 30 km [19 mi] along depositional strike), near-linear, north-northeast–south-southwest-trending clinoforms that dip west-northwestward at 1.5°–4° (Dreyer et al., 2005; Patruno et al., 2015). The structure of the Troll West reservoir is defined by two rotated fault blocks that formed after reservoir deposition, and the reservoir is further segmented by smaller postdepositional faults that trend west-northwest–east-southeast to north-northwest–south-southeast (Dreyer et al., 2005) ([[:File:BLTN13190fig12.jpg|Figure 12B]]).

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Troll West contains a thin oil column (11–26 m [36–85 ft]) that is exploited through the use of horizontal wells (Dreyer et al., 2005), the productivity of which is sensitive to the ratio of vertical-to-horizontal permeability (cf. Joshi, 1987). This ratio is predicted to be influenced by the calcite-cemented concretionary beds that are abundant in the Sognefjord Formation (Kantorowicz et al., 1987; Lien et al., 1992; Evensen et al., 1993). These are present within delta-front parasequences, which are seismically imaged as clinoform sets, and along their bounding flooding surfaces (Gibbons et al., 1993; Bakke et al., 1996; Dreyer et al., 2005; Holgate et al., 2014; Patruno et al., 2015). The Jurassic Bridport Sand Formation, a close sedimentologic analog present onshore United Kingdom, contains similarly abundant calcite-cemented concretionary beds. These are observed at the outcrop to be laterally extensive (>80% areal coverage) along bedding planes and in a producing subsurface reservoir; their presence is marked by breaks in pressure and fluid saturation within seismically imaged clinoform sets (Morris et al., 2006~~; Hampson et al., 2014~~). Thus it appears probable that permeability barriers and baffles in the form of calcite-cemented concretionary layers occur along clinoforms in the Troll Field reservoir and could influence drainage patterns and recovery from the thin oil zone (Gibbons et al., 1993); this may have been recognized previously and shown to impact on well test interpretations (Lien et al., 1991; Haug, 1992). However, to date, the heterogeneity associated with clinoforms has not been explicitly included in reservoir or flow-simulation models of the Sognefjord Formation in the Troll Field. Dilib et al. (2015) created a sector model of the Sognefjord Formation (dimensions: 3200 × 750 × 150 m [10,499 × 2461 × 492 ft]) to investigate production optimization using intelligent wells for a range of uncertainty in geologic parameters and their model, extracted and refined from the existing full field geological model, was used here as the context in which to apply the clinoform-modeling algorithm.

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Troll West contains a thin oil column (11–26 m [36–85 ft]) that is exploited through the use of horizontal wells (Dreyer et al., 2005), the productivity of which is sensitive to the ratio of vertical-to-horizontal permeability (cf. Joshi, 1987). This ratio is predicted to be influenced by the calcite-cemented concretionary beds that are abundant in the Sognefjord Formation (Kantorowicz et al., 1987; Lien et al., 1992; Evensen et al., 1993). These are present within delta-front parasequences, which are seismically imaged as clinoform sets, and along their bounding flooding surfaces (Gibbons et al., 1993; Bakke et al., 1996; Dreyer et al., 2005; Holgate et al., 2014; Patruno et al., 2015). The Jurassic Bridport Sand Formation, a close sedimentologic analog present onshore United Kingdom, contains similarly abundant calcite-cemented concretionary beds. These are observed at the outcrop to be laterally extensive (>80% areal coverage) along bedding planes and in a producing subsurface reservoir; their presence is marked by breaks in pressure and fluid saturation within seismically imaged clinoform sets.<ref>Hampson, G. J., J. E. Morris, and H. D. Johnson, 2014, Synthesis of time-stratigraphic relationships and their impact on hydrocarbon reservoir distribution and performance, Bridport Sand Formation, Wessex Basin, UK, inD. G. Smith, R. J. Bailey, P. M. Burgess, and A. J. Fraser, eds., Strata and time: Probing the gaps in our understanding: Geological Society, London, Special Publication 404, first published online on March 19, 2014, doi: 10.1144/SP404.2.</ref> (Morris et al., 2006) Thus it appears probable that permeability barriers and baffles in the form of calcite-cemented concretionary layers occur along clinoforms in the Troll Field reservoir and could influence drainage patterns and recovery from the thin oil zone (Gibbons et al., 1993); this may have been recognized previously and shown to impact on well test interpretations (Lien et al., 1991; Haug, 1992). However, to date, the heterogeneity associated with clinoforms has not been explicitly included in reservoir or flow-simulation models of the Sognefjord Formation in the Troll Field. Dilib et al. (2015) created a sector model of the Sognefjord Formation (dimensions: 3200 × 750 × 150 m [10,499 × 2461 × 492 ft]) to investigate production optimization using intelligent wells for a range of uncertainty in geologic parameters and their model, extracted and refined from the existing full field geological model, was used here as the context in which to apply the clinoform-modeling algorithm.

===Model Construction===

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The stratigraphic framework of the reservoir model is defined by flooding surfaces that bound seven parasequences. The bounding surfaces are offset by two postdepositional faults that are oriented northwest–southeast across the model volume. The faulted parasequence-bounding flooding surfaces were extracted from the existing reservoir model (Dilib et al., 2015). The faulted parasequence boundaries were used to construct the final Troll West sector model but, as a quality control step for applying the clinoform-modeling algorithm, these boundaries were adjusted so that they were horizontal. Each parasequence also contains a surface that represents the facies-association boundary between m sands below and c sands above; these surfaces were extracted from the model of Dilib et al. (2015) and are laterally continuous across the clinoforms modeled here, because they were extracted from a model that omits clinoforms. Consequently, facies interfingering across clinoforms is not captured here, and this may further increase the impact of modeling clinoforms on flow.<ref name=Jckson2009 /> The facies-association boundary surfaces were adjusted to remove the effects of faulting in the same way as the flooding surfaces. Additionally, where facies associations pinch out, the facies association boundary surfaces are adjusted to coincide throughout the remainder of the model volume with the top parasequence bounding surface. This procedure created flooding surfaces and facies-association boundaries in the model that mimic their depositional geometries, which were used as a reference framework to validate that the clinoform geometries and distributions applied later using the faulted parasequence-bounding surfaces are consistent with geologic concepts.

−

Table 4 shows the parameters used in the clinoform-modeling algorithm. To honor the nearly linear plan-view geometry of clinoforms observed in seismic data (figures 3, 12 in Dreyer et al., 2005), a width for the top-clinoform ellipse (''ts'') that is far greater than the depositional-dip extent of the bounding surfaces in the model area (3200 m [10,499 ft]) was defined; the top-clinoform ellipse length ''tD'' is half of ''ts'', to give a plan-view aspect ratio of 2 (cf. wave-dominated shoreface systems in Howell et al.<ref name=Hwll2008a />). Seismically resolved clinoform dip values of 1.5°–4° (Dreyer et al., 2005; Patruno et al., 2015) were used in conjunction with the estimated parasequence thickness to calculate clinoform length (''L'') using simple trigonometry. As there are only a small number of seismically resolved clinoforms in a few paleogeographic locations and within a few stratigraphic levels to extract clinoform length, a normal distribution based on the extracted data was generated ([[:File:BLTN13190fig13.jpg|Figure 13A]]), and values were then drawn at random from this distribution to populate the model volume ([[:File:BLTN13190fig13.jpg|Figure 13A]]). Finally, the premodeling lengths were compared with the seismically resolved clinoforms (Dreyer et al., 2005) to validate that the algorithm-generated lengths are reasonable. Similarly, the horizontal spacing of seismically resolved clinoforms (figures 3, 12 in Dreyer et al., 2005) was used to generate a normal distribution of values for clinoform spacing, S ([[:File:BLTN13190fig13.jpg|Figure 13B]]), and values were drawn at random from this distribution to populate the model volume ([[:File:BLTN13190fig13.jpg|Figure 13B]]). The resulting values of clinoform length and spacing are consistent with those observed at the outcrop for other wave-dominated shorelines (e.g., Hampson~~, 2000~~; Sech et al.<ref name=Sch09 />) ([[:File:BLTN13190fig13.jpg|Figure 13]]). A value of 2 was used for the exponent in the clinoform shape function (defined by ''P'' in equation 8), as this gives a good match to the seismically resolved clinoforms; and, furthermore, it was assumed that a similar geometry is shared by clinoforms in all parasequences in all locations throughout the model volume, consistent with observations of seismically resolved clinoforms over similar-size volumes (Patruno et al., 2015). Although, ''P'' has the same value as used in the Ferron Sandstone Member example, ''L'' values in the Troll Field sector model are larger ([[:File:BLTN13190fig13.jpg|Figure 13A]], Table 4) such that clinoform dip angles are shallower, consistent with the seismically resolved clinoforms (Dreyer et al., 2005; Patruno et al., 2015). As a first step, the insertion point of the first clinoform (''Po'') was arbitrarily selected in the center of the proximal model boundary, and consistent west-northwest progradation of clinoforms (Dreyer et al., 2005; Patruno et al., 2015) was used to define a ''θ'' of 320°. The facies-association boundary surfaces extracted from the model of Dilib et al. (2015) were then used to create zones of m sands and c sands within each clinothem. The application of the clinoform-modeling algorithm yields a model containing 100 clinoforms. A visual quality control check was then performed to ensure that the clinoforms produced by the algorithm are consistent with the geologic concepts of the model (e.g., clinoform spacing, dip, length) in the absence of postdepositional faults.

+

Table 4 shows the parameters used in the clinoform-modeling algorithm. To honor the nearly linear plan-view geometry of clinoforms observed in seismic data (figures 3, 12 in Dreyer et al., 2005), a width for the top-clinoform ellipse (''ts'') that is far greater than the depositional-dip extent of the bounding surfaces in the model area (3200 m [10,499 ft]) was defined; the top-clinoform ellipse length ''tD'' is half of ''ts'', to give a plan-view aspect ratio of 2 (cf. wave-dominated shoreface systems in Howell et al.<ref name=Hwll2008a />). Seismically resolved clinoform dip values of 1.5°–4° (Dreyer et al., 2005; Patruno et al., 2015) were used in conjunction with the estimated parasequence thickness to calculate clinoform length (''L'') using simple trigonometry. As there are only a small number of seismically resolved clinoforms in a few paleogeographic locations and within a few stratigraphic levels to extract clinoform length, a normal distribution based on the extracted data was generated ([[:File:BLTN13190fig13.jpg|Figure 13A]]), and values were then drawn at random from this distribution to populate the model volume ([[:File:BLTN13190fig13.jpg|Figure 13A]]). Finally, the premodeling lengths were compared with the seismically resolved clinoforms (Dreyer et al., 2005) to validate that the algorithm-generated lengths are reasonable. Similarly, the horizontal spacing of seismically resolved clinoforms (figures 3, 12 in Dreyer et al., 2005) was used to generate a normal distribution of values for clinoform spacing, S ([[:File:BLTN13190fig13.jpg|Figure 13B]]), and values were drawn at random from this distribution to populate the model volume ([[:File:BLTN13190fig13.jpg|Figure 13B]]). The resulting values of clinoform length and spacing are consistent with those observed at the outcrop for other wave-dominated shorelines (e.g., Hampson;<ref name=Hmpsn2000 /> Sech et al.<ref name=Sch09 />) ([[:File:BLTN13190fig13.jpg|Figure 13]]). A value of 2 was used for the exponent in the clinoform shape function (defined by ''P'' in equation 8), as this gives a good match to the seismically resolved clinoforms; and, furthermore, it was assumed that a similar geometry is shared by clinoforms in all parasequences in all locations throughout the model volume, consistent with observations of seismically resolved clinoforms over similar-size volumes (Patruno et al., 2015). Although, ''P'' has the same value as used in the Ferron Sandstone Member example, ''L'' values in the Troll Field sector model are larger ([[:File:BLTN13190fig13.jpg|Figure 13A]], Table 4) such that clinoform dip angles are shallower, consistent with the seismically resolved clinoforms (Dreyer et al., 2005; Patruno et al., 2015). As a first step, the insertion point of the first clinoform (''Po'') was arbitrarily selected in the center of the proximal model boundary, and consistent west-northwest progradation of clinoforms (Dreyer et al., 2005; Patruno et al., 2015) was used to define a ''θ'' of 320°. The facies-association boundary surfaces extracted from the model of Dilib et al. (2015) were then used to create zones of m sands and c sands within each clinothem. The application of the clinoform-modeling algorithm yields a model containing 100 clinoforms. A visual quality control check was then performed to ensure that the clinoforms produced by the algorithm are consistent with the geologic concepts of the model (e.g., clinoform spacing, dip, length) in the absence of postdepositional faults.

{| class = wikitable

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</gallery>

−

The clinoforms incorporated into the Troll sector model show similar geometries and spacing to those that are seismically resolved in the Sognefjord Formation (Dreyer et al., 2005; Patruno et al., 2015). The clinoforms are linear in plan view over the small (750 m [2461 ft]) depositional-strike extent of the model ([[:File:BLTN13190fig14.jpg|Figure 14B]]), consistent with the interpreted plan-view geometries of wave-dominated shoreface systems ([[:File:BLTN13190fig3.jpg|Figure 3A]]),<ref name=Hwll2008a /> consistently prograde west-northwestward (θ = 320°), as established through 3-D seismic data (Dreyer et al., 2005; Patruno et al., 2015), and have the concave-upward geometry observed in seismic dip sections through the Sognefjord Formation (Dreyer et al., 2005; Patruno et al., 2015) (Figures 14A, 15B). In depositional strike cross section, the algorithm produces near-horizontal clinoform geometries, consistent with seismically resolved clinoforms (Dreyer et al., 2005; Patruno et al., 2015) ([[:File:BLTN13190fig15.jpg|Figure 15C]]). The stochastic component of the clinoform-modeling algorithm distributes clinoforms with cross-sectional geometries and spacings (Figures 14A, 15B) that are consistent with outcrop studies of wave-dominated deltas (Hampson, 2000; <ref name=Sch09 />) ([[:File:BLTN13190fig13.jpg|Figure 13]]) and honor the sparse subsurface data. In contrast to the Ferron Sandstone Member example, the Troll West sector model does not contain subtle clinoform geometries, such as onlap and downlap of younger clinoforms on to older clinoforms ([[:File:BLTN13190fig14.jpg|Figures 14A]], [[:File:BLTN13190fig15.jpg|15B]]). Such features are below the resolution of the seismic data used to extract the parameters that were used in the algorithm. The clinoforms are also faulted in the same way as the parasequence-bounding flooding surfaces (cf. [[:File:BLTN13190fig2.jpg|Figures 2A]], [[:File:BLTN13190fig15.jpg|15C]]).

+

The clinoforms incorporated into the Troll sector model show similar geometries and spacing to those that are seismically resolved in the Sognefjord Formation (Dreyer et al., 2005; Patruno et al., 2015). The clinoforms are linear in plan view over the small (750 m [2461 ft]) depositional-strike extent of the model ([[:File:BLTN13190fig14.jpg|Figure 14B]]), consistent with the interpreted plan-view geometries of wave-dominated shoreface systems ([[:File:BLTN13190fig3.jpg|Figure 3A]]),<ref name=Hwll2008a /> consistently prograde west-northwestward (θ = 320°), as established through 3-D seismic data (Dreyer et al., 2005; Patruno et al., 2015), and have the concave-upward geometry observed in seismic dip sections through the Sognefjord Formation (Dreyer et al., 2005; Patruno et al., 2015) (Figures 14A, 15B). In depositional strike cross section, the algorithm produces near-horizontal clinoform geometries, consistent with seismically resolved clinoforms (Dreyer et al., 2005; Patruno et al., 2015) ([[:File:BLTN13190fig15.jpg|Figure 15C]]). The stochastic component of the clinoform-modeling algorithm distributes clinoforms with cross-sectional geometries and spacings (Figures 14A, 15B) that are consistent with outcrop studies of wave-dominated deltas<ref name=Hmpsn2000>Hampson, G. J., 2000, Discontinuity surfaces, clinoforms and facies architecture in a wave-dominated, shoreface-shelf parasequence: Journal of Sedimentary Research, v. 70, no. 2, p. 325–340, doi: 10.1306/2DC40914-0E47-11D7-8643000102C1865D.</ref><ref name=Sch09 /> ([[:File:BLTN13190fig13.jpg|Figure 13]]) and honor the sparse subsurface data. In contrast to the Ferron Sandstone Member example, the Troll West sector model does not contain subtle clinoform geometries, such as onlap and downlap of younger clinoforms on to older clinoforms ([[:File:BLTN13190fig14.jpg|Figures 14A]], [[:File:BLTN13190fig15.jpg|15B]]). Such features are below the resolution of the seismic data used to extract the parameters that were used in the algorithm. The clinoforms are also faulted in the same way as the parasequence-bounding flooding surfaces (cf. [[:File:BLTN13190fig2.jpg|Figures 2A]], [[:File:BLTN13190fig15.jpg|15C]]).

===Production Strategy===

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# Google Earth and DigitalGlobe, 2013, accessed January 14, 2013, http://www.google.co.uk/intl/en_uk/earth/index.html.

# Google Earth and TerraMetrics, 2013, accessed January 14, 2013, http://www.google.co.uk/intl/en_uk/earth/index.html.

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#

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# Hampson, G. J., 2000, Discontinuity surfaces, clinoforms and facies architecture in a wave-dominated, shoreface-shelf parasequence: Journal of Sedimentary Research, v. 70, no. 2, p. 325–340, doi: 10.1306/2DC40914-0E47-11D7-8643000102C1865D.

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# Hampson, G. J., J. E. Morris, and H. D. Johnson, 2014, Synthesis of time-stratigraphic relationships and their impact on hydrocarbon reservoir distribution and performance, Bridport Sand Formation, Wessex Basin, UK, inD. G. Smith, R. J. Bailey, P. M. Burgess, and A. J. Fraser, eds., Strata and time: Probing the gaps in our understanding: Geological Society, London, Special Publication 404, first published online on March 19, 2014, doi: 10.1144/SP404.2.

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#

# Haug, B. T., 1992, The second long-term horizontal well test in Troll: Successful production from a 13-in. oil column with the well partly completed in the water zone: SPE Paper 24943, 10 p.

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# Joshi, S. D., 1987, A review of horizontal well and drain hole technology: SPE Paper 16868, 17 p.

# Kantorowicz, J. D., I. D. Bryant, and J. M. Dawans, 1987, Controls on the geometry and distribution of carbonate cements in Jurassic sandstones: Bridport Sands, southern England and Viking Group, Troll Field, Norway, inJ. D. Marshall, ed., Diagenesis of sedimentary sequences: Geological Society, London, Special Publication 36, p. 103–118.

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#

# Lien, S. C., H. H. Haldorsen, and M. Manner, 1992, Horizontal wells: Still appealing in formations with discontinuous vertical permeability barriers?: Journal of Petroleum Technology, v. 44, no. 12, p. 1364–1370, doi: 10.2118/20962-PA.

Line 400: Line 395:

# Olariu, C., J. P. Bhattacharya, X. Xu, C. L. Aiken, X. Zeng, and G. A. McMechan, 2005, Integrated study of ancient delta-front deposits, using outcrop ground-penetrating radar, and three-dimensional photorealistic data: Cretaceous Panther Tongue Sandstone, Utah, U.S.A., inL. Giosan, and J. P. Bhattacharya, eds., River deltas—Concepts, models and examples: Tulsa, Oklahoma, SEPM Special Publication 83, p. 155–177.

# Patruno, S., G. J. Hampson, C. A.-L. Jackson, and T. Dreyer, 2015, Clinoform geometry, geomorphology, facies character and stratigraphic architecture of a sand-rich subaqueous delta: Jurassic Sognefjord Formation, offshore Norway: Sedimentology, v. 62, no. 1, p. 350–388, doi: 10.1111/sed.12153.

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# Pirmez, C., L. F. Pratson, and M. S. Steckler, 1998, Clinoform development by advection-diffusion of suspended sediment; modeling and comparison to natural systems: Journal of Geophysical Research B: Solid Earth and Planets, v. 103, p. 24,141–24,157, doi: 10.1029/98JB01516.

#

# Ryer, T. A., 1991, Stratigraphy, facies and depositional history of the Ferron Sandstone in the Canyon of Muddy Creek, east-central Utah, inT. C. Chidsey, Jr., ed., Geology of east-central Utah: Utah Geological Association Publication 19, p. 45–54.

# Ryer, T. A., and P. B. Anderson, 2004, Facies of the Ferron Sandstone, east-central Utah, inT. C. Chidsey, Jr., R. D. Adams, and T. H. Morris, eds., Regional to wellbore analog for fluvial-deltaic reservoir modeling: The Ferron Sandstone of Utah: AAPG Studies in Geology 50, p. 59–78.

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#

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# Steckler, M. S., G. S. Mountain, K. G. Miller, and N. Christie-Blick, 1999, Reconstruction of tertiary progradation and clinoform development on the New Jersey passive margin by 2D backstripping: Marine Geology, v. 154, no. 1–4, p. 399–420, doi: 10.1016/S0025-3227(98)00126-1.

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~~# Swift, D. J., 1968, Coastal erosion and transgressive stratigraphy: Journal of Geology, v. 76, no. 4, p. 444–456, doi: 10.1086/jg.1968.76.issue-4.~~

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#

# Vinje, J., R. Nybø, and G. Grinestaff, 2011, A new simulation grid type is demonstrated for the giant Troll oil and gas field: SPE Paper 148023, 14 p.

#

# White, C. D., and M. D. Barton, 1999, Translating outcrop data to flow models, with applications to the Ferron Sandstone: SPE Reservoir Evaluation and Engineering, v. 2, no. 4, p. 341–350, doi: 10.2118/57482-PA.

# White, C. D., B. J. Willis, S. P. Dutton, J. P. Bhattacharya, and K. Narayanan, 2004, Sedimentology, statistics, and flow behaviour for a tide-influenced deltaic sandstone, Frontier Formation, Wyoming, United States, inG. M. Grammer, P. M. Harris, and G. P. Eberli, eds., Integration of outcrop and modern analogs in reservoir modeling: AAPG Memoir 80, p. 129–152.

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