Sedimentology of multistorey fluvial sandstones of the Mississippian Cypress Formation, Illinois Basin, USA
type: CreativeWork
description: The Cypress Formation (Upper Mississippian) is the most oil-productive unit in the Illinois Basin, USA. In the central part of the basin, the Cypress Formation contains sandstones up to 60 m thick in a northeast-southwest trending belt known as the Western Belt. Thick Western Belt sandstones have potential for nonconventional carbon dioxide enhanced oil recovery (CO2 -EOR) and storage, whereby CO2 injection aims to store appreciable volumes of anthropogenic CO2 and produce incremental oil at the same time. However, the depositional environments and resultant depositional controls on reservoir heterogeneity are currently poorly understood. This study provides the geologic context necessary for building representative geocellular models and helping select a proper CO2 injection strategy to co-optimize CO2 storage and EOR in thick sandstones of the Western Belt. Consequently, this study also provides new insight into the dynamics of Carboniferous sedimentation in the Illinois Basin. Using new cores, outcrops and well logs, thick Western Belt sandstones were recognized to be predominantly multistorey, lowstand deposits of a fine-grained (D50 = 132 µm), meandering or anastomosing fluvial system that had a high affinity toward suspended load transport. Principal sandstone lithofacies all contain exceptionally low volumes of detrital clay and include: unidirectional simple dune cross-sets, low amplitude (<3 m) – high wavelength (10s of meters) dune cross-sets, asymmetric ripple cross-sets, and upper-stage plane beds. Mean simple cross-set thickness is 0.3 m, and foresets are commonly low-angle (<15º) and sigmoidal or convex-up with tangential toesets. Simple dune cross-sets are commonly superimposed on low amplitude (< 3 m) – high wavelength (10s of meters) dune cross-set or bar-scale accretion surfaces. Lithofacies associations in core suggest up to three channel fill storeys that form sheet-like or arcuate channel elements. These elements, along with abandoned channel cl…
abstract: The Cypress Formation (Upper Mississippian) is the most oil-productive unit in the Illinois Basin, USA. In the central part of the basin, the Cypress Formation contains sandstones up to 60 m thick in a northeast-southwest trending belt known as the Western Belt. Thick Western Belt sandstones have potential for nonconventional carbon dioxide enhanced oil recovery (CO2 -EOR) and storage, whereby CO2 injection aims to store appreciable volumes of anthropogenic CO2 and produce incremental oil at the same time. However, the depositional environments and resultant depositional controls on reservoir heterogeneity are currently poorly understood. This study provides the geologic context necessary for building representative geocellular models and helping select a proper CO2 injection strategy to co-optimize CO2 storage and EOR in thick sandstones of the Western Belt. Consequently, this study also provides new insight into the dynamics of Carboniferous sedimentation in the Illinois Basin. Using new cores, outcrops and well logs, thick Western Belt sandstones were recognized to be predominantly multistorey, lowstand deposits of a fine-grained (D50 = 132 µm), meandering or anastomosing fluvial system that had a high affinity toward suspended load transport. Principal sandstone lithofacies all contain exceptionally low volumes of detrital clay and include: unidirectional simple dune cross-sets, low amplitude (<3 m) – high wavelength (10s of meters) dune cross-sets, asymmetric ripple cross-sets, and upper-stage plane beds. Mean simple cross-set thickness is 0.3 m, and foresets are commonly low-angle (<15º) and sigmoidal or convex-up with tangential toesets. Simple dune cross-sets are commonly superimposed on low amplitude (< 3 m) – high wavelength (10s of meters) dune cross-set or bar-scale accretion surfaces. Lithofacies associations in core suggest up to three channel fill storeys that form sheet-like or arcuate channel elements. These elements, along with abandoned channel cl…
author: Howell, Kalin Joseph
language: en
keywords: Cypress formation, Sedimentology, Enhanced oil recovery, CO2 storage, Fluvial, Illinois Basin, Carboniferous, Mississippian, Chesterian, Facies, Depositional environment, Sequence stratigraphy, Lowstand, Fine-grained, Suspended-load transport, Paleohydraulics, Reservoir, River, Outcrop, Illinois State Geological Survey, Western Belt
date published: 2017-09-29T17:56:56Z
date modified: 2026-07-22T22:24:35Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/98399