Structural Analysis of Aneth Field, Paradox Basin, Southeastern Utah: A Carbon Storage Study Site of the Southwest Regional Partnership for Carbon Sequestration
Carney, Stephanie, Craig Morgan, and Michael Vanden Berg
Utah Geological Survey, Salt Lake City, UT
Aneth oil field is one of three pilot project sites selected by the
Southwest Regional Partnership for Carbon Sequestration for CO2
injection and monitoring. Surface and subsurface structural analysis
of the site was done, in part, to characterize the oil-producing and
potential CO2 storage reservoir, the Pennsylvanian Paradox
Formation, as well as identify possible pathways for CO2 migration to
the surface.
Surface fractures (deformation bands) and faults were mapped in
the area to identify structural links between the surface and the
reservoir at depth. We measured orientations of >1000 deformation
bands and identified a few small, localized normal faults within the
Jurassic Morrison Formation. Deformation bands appear randomly
oriented and cannot be linked to any regional tectonic
structures. Faults have small, vertical offsets (<5 m) and are likely
shallow structures. These surface structures are probably a result of
gravity-driven deformation.
Subsurface analysis included correlating and picking formation
tops from over 200 well logs in the project area. Structure contour
maps created at the reservoir level and cross sections between wells
show a northeast-trending, high-angle fault that cuts through the
Paradox Formation. The fault likely extends through younger
Pennsylvanian strata, but dies out before entering Permian
strata. Evidence of the fault is also seen in intense fracturing in the
Paradox in core from a well near the fault.
These initial analyses indicate that surface and subsurface
structures are not linked and migration of CO2 from the reservoir to
the surface is unlikely. Expanded analysis is needed to further
characterize subsurface structures.
AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah