Facies-to sandbody-scale heterogeneity in a tight-gas fluvial reservoir analog: Blackhawk Formation, Wasatch Plateau, Utah, USA
File(s)Sahoo-et-al-in-press-MPG.pdf (2.09 MB)
Accepted version
Author(s)
Sahoo, H
Gani, MR
Hampson, GJ
Gani, ND
Ranson, A
Type
Journal Article
Abstract
Using photomosaics and measured sections, this outcrop study characterizes facies-to sandbody-scale heterogeneity in the fluvial and coastal-plain deposits of the Blackhawk Formation of the Wasatch Plateau, Utah, USA, as an outcrop analog for the fluvial tight-gas reservoirs of the adjacent greater western Rocky Mountain basins as well as for conventional fluvial reservoirs elsewhere. Analysis on eight contiguous, vertical cliff-faces comprising both depositional-dip- and -strike-oriented segments provides field-validation and calibration of entire range of fluvial heterogeneity, where: 1) large-scale heterogeneity (10’s of m vertically and 100’s of m laterally) is associated with stacking of channelized fluvial sandbodies encased within coastal-plain fines, 2) intermediate-scale heterogeneity (1’s of m vertically and 10’s of m laterally) is related to type and distribution of architectural elements like bar-accretion and crevasse-splay units within individual sandbodies, and 3) small-scale heterogeneity (10’s of cm vertically and 1’s of m laterally) is attributed to facies spatial variability within individual architectural elements.
At a reservoir-scale (∼6 km strike-transect), impact of these heterogeneities has resulted in potential stratigraphic compartmentalization in varied patterns and scales within and among three zones, which have similar lateral extents. Distinct vertical or lateral compartmentalization, contrasting net-to-gross pattern, width-constraint by either large- or intermediate-scale heterogeneity, disparity in communication between principal reservoir compartments by intermediate-scale heterogeneity, and reservoir-quality segregation to barrier styles rendered by small-scale heterogeneity are documented in an array of trends. These intriguing trends are challenging to correlate across the reservoir-scale dataset, contributing to multiple, analogous exploration and production uncertainties. For improved tight-gas exploration and production strategy of the western Rocky Mountain basins, study results were also used in developing potential predictive tools: 1) thickness threshold of individual channelized sandbody favoring multiple well intersection, 2) aspect ratio in performing probabilistic sandbody-width estimation, and 3) prediction of sandbody amalgamation using underlying coal thickness.
At a reservoir-scale (∼6 km strike-transect), impact of these heterogeneities has resulted in potential stratigraphic compartmentalization in varied patterns and scales within and among three zones, which have similar lateral extents. Distinct vertical or lateral compartmentalization, contrasting net-to-gross pattern, width-constraint by either large- or intermediate-scale heterogeneity, disparity in communication between principal reservoir compartments by intermediate-scale heterogeneity, and reservoir-quality segregation to barrier styles rendered by small-scale heterogeneity are documented in an array of trends. These intriguing trends are challenging to correlate across the reservoir-scale dataset, contributing to multiple, analogous exploration and production uncertainties. For improved tight-gas exploration and production strategy of the western Rocky Mountain basins, study results were also used in developing potential predictive tools: 1) thickness threshold of individual channelized sandbody favoring multiple well intersection, 2) aspect ratio in performing probabilistic sandbody-width estimation, and 3) prediction of sandbody amalgamation using underlying coal thickness.
Date Issued
2016-02-05
Date Acceptance
2016-02-03
Citation
Marine and Petroleum Geology, 2016, 78, pp.48-69
ISSN
0264-8172
Publisher
Elsevier
Start Page
48
End Page
69
Journal / Book Title
Marine and Petroleum Geology
Volume
78
Copyright Statement
© 2016, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Chevron Energy Technology Company
Grant Number
N/A
Subjects
Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
Fluvial heterogeneity
Stratigraphic compartmentalization
Cretaceous Blackhawk Formation
Tight-gas
Utah
Outcrop
Reservoir analog
WILLIAMS-FORK FORMATION
STAR POINT SANDSTONE
INCISED-VALLEY FILL
CRETACEOUS BLACKHAWK
PICEANCE BASIN
BOOK CLIFFS
SEQUENCE STRATIGRAPHY
ARCHITECTURE
COLORADO
OUTCROP
0403 Geology
0404 Geophysics
Publication Status
Published