Changes

[[Fluvial]] reservoirs are difficult for the production geologist to understand, characterize, and model. One major problem involves trying to classify fluvial reservoirs in the [[subsurface]]. The system used in this article broadly categorizes fluvial systems into meandering and [[braided fluvial reservoirs]]. Although this is a classification used by many production geologists, not all experts are happy with this approach; some believe the classification to be too prescriptive. They consider that only limited inferences can be made from core and log data as to the overall geometry of a fluvial reservoir in the subsurface (e.g., Bridge<ref name=Bridge_2003>Bridge, J. S., 2003, Rivers and flood plains: Forms, processes and sedimentary record: Oxford, Blackwell, 491 p.</ref>). Because of this, some geologists prefer to use a simple nongeneric description by classifying subsurface fluvial geometries as either sheets or ribbons.<ref name=Friendetal_1979>Friend, P. F., M. J. Slater, and R. C. Williams, 1979, [http://jgs.geoscienceworld.org/content/136/1/39.abstract Vertical and [[lateral]] building of river sandstone bodies, Ebro Basin, Spain]: Journal of the Geological Society of London, v. 136, p. 39–46.</ref>

[[Fluvial]] reservoirs are difficult for the production geologist to understand, characterize, and model. One major problem involves trying to classify fluvial reservoirs in the [[subsurface]]. The system used in this article broadly categorizes fluvial systems into meandering and [[braided fluvial reservoirs]]. Although this is a classification used by many production geologists, not all experts are happy with this approach; some believe the classification to be too prescriptive. They consider that only limited inferences can be made from core and log data as to the overall geometry of a fluvial reservoir in the subsurface (e.g., Bridge<ref name=Bridge_2003>Bridge, J. S., 2003, Rivers and flood plains: Forms, processes and sedimentary record: Oxford, Blackwell, 491 p.</ref>). Because of this, some geologists prefer to use a simple nongeneric description by classifying subsurface fluvial geometries as either sheets or ribbons.<ref name=Friendetal_1979>Friend, P. F., M. J. Slater, and R. C. Williams, 1979, [http://jgs.geoscienceworld.org/content/136/1/39.abstract Vertical and [[lateral]] building of river sandstone bodies, Ebro Basin, Spain]: Journal of the Geological Society of London, v. 136, p. 39–46.</ref>

[[file:M91Ch11FG70.JPG|thumb|300px|{{figure number|1}}A point bar cut into the underlying Ivan limestone as picked out by varying seismic amplitudes on a horizon display, late Pennsylvanian to Early Permian, Baylor County, Texas (from Burnett<ref name=Burnett_1996>Burnett, M., 1996, [http://archives.datapages.com/data/specpubs/study42/ch05/0062.htm 3-D seismic expression of a shallow fluvial system in west central Texas], in P. Weimer and T. L. Davis, eds.: AAPG Studies in Geology 42 and SEG (Society of Exploration Geophysicists) Geophysical Developments Series 5, p. 45–56.</ref>). Reprinted with permission from the AAPG.]]

[[file:M91Ch11FG70.JPG|thumb|300px|{{figure number|1}}A point bar cut into the underlying Ivan [[limestone]] as picked out by varying seismic amplitudes on a horizon display, late Pennsylvanian to Early Permian, Baylor County, Texas (from Burnett<ref name=Burnett_1996>Burnett, M., 1996, [http://archives.datapages.com/data/specpubs/study42/ch05/0062.htm 3-D seismic expression of a shallow fluvial system in west central Texas], in P. Weimer and T. L. Davis, eds.: AAPG Studies in Geology 42 and SEG (Society of Exploration Geophysicists) Geophysical Developments Series 5, p. 45–56.</ref>). Reprinted with permission from the AAPG.]]

Despite the above difficulties, the production geologist will nevertheless try and find some basis for providing a predictive model for the subsurface geology of a fluvial reservoir. Seismic data can help to determine the planform geometry where it is of sufficient resolution ([[:file:M91Ch11FG70.JPG|Figure 1]]). Fluvial geometries can sometimes be well differentiated on horizon slice amplitude displays (e.g., Brown et al.,<ref name=Brownetal_1981>Brown, A. R., C. G. Dahm, and R. J. Graebner, 1981, A stratigraphic case history using three-dimensional seismic data in the Gulf of Thailand: Geophysical Prospecting, v. 29, no. 3, p. 327–349.</ref> Rijks and Jauffred,<ref name=Rijksandjauffred_1991>Rijks, E. J. K., and J. C. E. M. Jauffred, 1991, Attribute extraction: An important application in any detailed 3D interpretation study: Leading Edge, v. 10, no. 9, p. 11–19.</ref> Noah et al.,<ref name=Noahetal_1992>Noah, J. T., G. S. Hofland, and K. Lemke, 1992, Seismic interpretation of meander channel point-bar deposits using realistic seismic modeling techniques: The Leading Edge, v. 11, p. 13–18.</ref> Carter<ref name=Carter_2003>Carter, D. C., 2003, [http://archives.datapages.com/data/bulletns/2003/06jun/0909/0909.HTM 3-D seismic geomorphology:  Insights into fluvial reservoir deposition and performance, Widuri field, Java Sea]: AAPG Bulletin, v. 87, no. 6, p. 909–934.</ref>).

Despite the above difficulties, the production geologist will nevertheless try and find some basis for providing a predictive model for the subsurface geology of a fluvial reservoir. Seismic data can help to determine the planform geometry where it is of sufficient resolution ([[:file:M91Ch11FG70.JPG|Figure 1]]). Fluvial geometries can sometimes be well differentiated on horizon slice amplitude displays (e.g., Brown et al.,<ref name=Brownetal_1981>Brown, A. R., C. G. Dahm, and R. J. Graebner, 1981, A stratigraphic case history using three-dimensional seismic data in the Gulf of Thailand: Geophysical Prospecting, v. 29, no. 3, p. 327–349.</ref> Rijks and Jauffred,<ref name=Rijksandjauffred_1991>Rijks, E. J. K., and J. C. E. M. Jauffred, 1991, Attribute extraction: An important application in any detailed 3D interpretation study: Leading Edge, v. 10, no. 9, p. 11–19.</ref> Noah et al.,<ref name=Noahetal_1992>Noah, J. T., G. S. Hofland, and K. Lemke, 1992, Seismic interpretation of meander channel point-bar deposits using realistic seismic modeling techniques: The Leading Edge, v. 11, p. 13–18.</ref> Carter<ref name=Carter_2003>Carter, D. C., 2003, [http://archives.datapages.com/data/bulletns/2003/06jun/0909/0909.HTM 3-D seismic geomorphology:  Insights into fluvial reservoir deposition and performance, Widuri field, Java Sea]: AAPG Bulletin, v. 87, no. 6, p. 909–934.</ref>).