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Reservoir
Geometry of the
Regressive Fox Hills Sandstone:
Control on Aquifer Quality*
Search and Discovery Article #50025 (2005)
Posted November 27, 2005
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In the Denver Basin the littoral to
nearshore Fox Hills Sandstone was deposited during the early phase of the
Laramide orogeny as the Cretaceous Interior Seaway retreated to the northeast.
This approximately 68 MY regressive sandstone is composed of a series of
shingles reflecting episodic seaway retreat. We illustrate the detailed geometry
of the sandstone elements that make up the Fox Hills Sandstone. This unit is an
important aquifer in the Denver Basin and the distribution of porosity,
permeability, and facies tracts is important in predicting the performance of
water wells.
A database of thousands of oil and gas wells and
thousands of water wells is available for study. A subset of these wells has
been analyzed to create a three-dimensional model using ArcGIS software. Seven
shingles are mapped in detail. Our three dimensional model permits the effective
and efficient communication of critical reservoir parameters to resource
planners. Comparisons are made to other well-studied regressive systems in the
San Juan and Greater Green River basins. We propose that non-uniform subsidence
has influenced the stacking pattern of this regressive succession, controlling
both the distribution of net sandstone and of coal-bearing strata. These
parameters are critical to predicting reservoir
performance and quality. The
patterns we document are relevant to any effort to extract fluids from rocks of
this facies association.
Source of water supply, Denver Basin area
