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Hierarchical levels of heterogeneity in a Mississippi River meander belt and application to reservoir systems

Douglas W. Jordan and Wayne A. Pryor
Hierarchical levels of heterogeneity in a Mississippi River meander belt and application to reservoir systems
AAPG Bulletin (October 1992) 76 (10): 1601-1624

Abstract

Six hierarchical levels of sand heterogeneity that would be present in analogous reservoirs are recognized in a Mississippi River meander-belt system in southeastern Missouri: (1) meander belt, (2) meander scroll, (3) channel, point bar, and splay, (4) lobe sheet, (5) bedding unit, and (6) laminae. Heterogeneity level 1 is similar in size to an oil field and consists of (1) 9 million ac-ft (11.1 billion m3) of high-permeability channel sands in numerous meander scrolls and (2) 4 million ac-ft (4.9 billion m3) of low-permeability clay plugs (in numerous abandoned channels) that separate a field into isolated pools and reservoirs. Overbank flood-plain muds capping the meander-belt system are barriers to vertical migration of fluids. Heterogeneity level 2 is the size of pools within a field and has 1.2 million ac-ft (1.5 billion m3) of highly permeable, laterally accreted channel and point-bar sands, partly or wholly isolated from other sand bodies by low-permeability, abandoned-channel clay plugs. Abandoned mud-filled chutes impede lateral migration of fluids in the upper parts of the meander scroll. The third level of heterogeneity is composed of about 70,000 ac-ft (86.3 million m3) of individual, permeable channel, point-bar, and crevasse-splay sand bodies, with numerous thin sheets and lenses of low-permeability muds and silts (derived from chute fill and mud drapes) that impede vertical migration of fluids. Heterogeneity level 4 is the lobe sheet unit (reservoir pay zone about 450 ac-ft or 555,000 m3 in volume) comprising channel, point-bar, and splay sand bodies. The fifth level of heterogeneity is the single bedding unit (about 10 ac-ft or 12,000 m3) at the scale of a reservoir flow unit or perforated interval. Permeable, cross-bedded sand bundles are separated by low-permeability, inclined and horizontal mud-silt layers and lenses present along bed-set boundaries. Heterogeneity level 6 is individual sand laminae (grain-flow lenses or grain-fall sheets) separated by textural variations (and hence permeability-porosity variations) and isolated mud-silt laminae. Permeabilities range from 90-160 d in sand; several millidarcys to 50 d in muddy sand, silt, and sandy silt beds from the levee, crevasse, and abandoned-channel fill; and less than 10 md in muddy silts and muds from abandoned-channel and chute-fill mud sheets and laminae. At all levels within a fluvial meander-belt system, these permeability heterogeneities are the principal controls on productivity throughout the life of a reservoir.


ISSN: 0149-1423
EISSN: 1558-9153
Coden: AABUD2
Serial Title: AAPG Bulletin
Serial Volume: 76
Serial Issue: 10
Title: Hierarchical levels of heterogeneity in a Mississippi River meander belt and application to reservoir systems
Affiliation: ARCO International Oil and Gas Company, Plano, TX, United States
Pages: 1601-1624
Published: 199210
Text Language: English
Publisher: American Association of Petroleum Geologists, Tulsa, OK, United States
References: 48
Accession Number: 1992-042410
Categories: Sedimentary petrologyEconomic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, block diags., sects., strat. cols., sketch maps
N29°00'00" - N47°13'00", W93°31'00" - W89°04'60"
N36°00'00" - N40°34'60", W95°45'00" - W89°04'60"
Secondary Affiliation: University of Cincinnati, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 1992
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