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Detailed Architectural Analysis of Two Point-Bar Complexes in the Cameo Interval of the Lower Williams Fork Formation from "Hoodoo Hill," Southwestern Piceance Basin, Colorado

Cole, Rex D.1; Pranter, Matthew J.2
1 Department of Physical and Environmental Sciences, Mesa State College, Grand Junction, CO.
2 Department of Geological Sciences, University of Colorado, Boulder, CO.

This study presents a detailed assessment of the internal compartmentalization and connectivity of two large multistory/multilateral fluvial complexes (1-240 and M-15) in the Cameo interval of the lower Williams Fork Formation (Late Cretaceous) at "Hoodoo Hill", which is approximately 2.2 miles northeast of Palisade, Colorado. Data were obtained from 46 detailed measured sections and outcrop mapping with GPS control. Both complexes were deposited by sinuous fluvial systems operating in a lower coastal-plain setting, and are thought to be accurate analogs for gas-producing reservoir elements in the subsurface. Lithofacies are similar in each complex; however, the proportions vary significantly.

Sandstone-body (SSB) 1-140 is 62 ft above the Rollins Member of the Iles Formation, has an outcrop width of 2,071 ft and thickness range from 0.8 to 22.7 ft (mean = 11.0 ft); paleocurrent measurements (N = 194) indicate a vector mean of 55 deg. Internally, SSB 1-240 consists of eight off-lapping point-bar and splay compartments ranging in thickness from 1.5 to 10.4 ft and in outcrop width from 55 to 1,538 ft. SSB 1-240 shows significant tidal influence and has internal mud plugs. Scour surfaces with siderite clasts and mudchips define most connection surfaces. SSB-M-15 is approximately 289 ft above the Rollins, is 2.0 to 35.0 ft thick (mean = 19.1 ft), has an outcrop width of 1,173 ft, a paleocurrent mean of 82 deg (N = 373), and consists of 16 point-bar compartments (1.4-11.5 ft thick). The largest compartment has an outcrop width of 1,700 ft. SSB M-15 is less heterogeneous than SSB 1-240 and does not exhibit tidal influence. Compartment connection points are mainly sand-on-sand surfaces.

Results of this study strongly suggest that the compartmentalization of fluvial complexes can complicate fluid flow and have adverse impacts on resource recovery at the inter-well scale.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009