Abstract

The Duchesne Fault Zone (DFZ) is a series of east-west trending en echelon faults that developed synchronously above the neutral surface of the Duchesne Anticline during the Laramide Orogeny. The Duchesne Graben (DG) formed by decrease in displacement downward toward the neutral surface. Lake Canyon, a region that exposes the subsurface geology on the western portion of the DFZ, serves as an analog for fold formation within the saline facies of the lower Green River Formation, while Indian Canyon, an area created from the dip-slip faulting of the DG, provides clear exposures of the faulting within the sandstone-limestone facies of the lower Green River Formation. These two canyons exhibit the different stress regimes that were present during the formation of these Laramide derived structures. This study builds on earlier work to test the hypothesis that subsurface compartmentalization of hydrocarbon reservoirs occurs within the DFZ. While prevailing theories suggest that fracturing within the DFZ enhances permeability and leads to high initial production, compartmentalization of fault-bounded rock blocks may restrict long-term hydrocarbon flow across fault core zones. The presence of an anticlinal fold within Indian Canyon, coupled with the overlying DG, indicates the coexistence of opposing stress regimes within the DFZ. The interaction between horizontal contraction at depth and extension above a neutral surface supports the compartmentalization theory, suggesting that extension-driven fault blocks could terminate fluid flow from preexisting hydraulic fractures. The implications for reservoir behavior and hydrocarbon recovery in the Uinta Basin are that Laramide derived stress regimes within the DFZ act as both conduits for increased permeability and seals for reservoir compartmentalization.

Degree

College and Department

Computational, Mathematical, and Physical Sciences; Geological Sciences

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