--> Abstract: The Upper Fort Union Petroleum System in the Wind River Basin, Wyoming: Documentation of Components and Exploration Trends, by L. M. Liro, B. J. Katz, and T. Jorjorian; #91017 (1992).

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ABSTRACT: The Upper Fort Union Petroleum System in the Wind River Basin, Wyoming: Documentation of Components and Exploration Trends

LIRO, L. M., B. J. KATZ, and T. JORJORIAN, Texaco E&P Technology Department, Houston, TX

The petroleum systems concept allows for a concise understanding of the occurrence and timing of those factors leading to hydrocarbon accumulation: source, maturation, migration, reservoir, and trap. These factors will be considered for the upper Fort Union Formation in the Wind River basin of Wyoming. The upper Fort Union records a fluvial-deltaic lacustrine environment. Enhanced subsidence due to Laramide tectonism led to the creation of a sizable lacustrine system. Proximal uplifts served as clastic source for two deltaic systems that encroached the lake, eventually filling the available accommodation space.Hydrocarbon source quality in the Waltman Shale Member is sufficient to serve as a viable oil source rock. Reservoir quality in the sands of the Shotgun Member is good enough to serve as a reservoir rock. A singular example of the upper Fort Union petroleum system, Haybarn field, produces out of distal deltaic Shotgun Member sandstones, with reservoired paraffinic

oil type back to mature Waltman Shale Member section. Trap is largely stratigraphic, by permeability pinch-out. In the absence of significant faulting, migration into the Haybarn reservoir is likely updip and bed parallel. Exploration in the upper Fort Union petroleum system depends on an understanding of reservoir distribution (primarily through seismic and well-log sequence stratigraphic interpretation) coupled with documentation of mature Waltman Shale Member section. Definition of migration pathways and the occurrence of stratigraphic trapping, the other key parameters in this petroleum system, will remain somewhat questionable until additional data have been obtained and evaluated.

 

AAPG Search and Discovery Article #91017©1992 AAPG Rocky Mountain Section Meeting, Casper, Wyoming, September 13-16, 1992 (2009)