Integrating structural observations and models to support subsurface applications: case studies from the Paradox Basin

Amanda Hughes, University of Arizona
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Abstract

Structural geology is critical for a wide variety of societally relevant applications that require subsurface predictions, including energy and mineral exploration and production, subsurface storage, and geotechnical and seismic hazard assessment. Because these all require interpolation between sparse, ambiguous, or incomplete subsurface data constraints afforded by wells, seismic, and other geologic or geophysical data, they usually require integrated application of various structural modeling approaches to reduce subsurface interpretation uncertainty. To demonstrate this, I will share results from recent case studies from the northern Paradox Basin in Utah in which we compare detailed observations and models to gain insight into structural processes in and around salt bodies and layered evaporite sequences. First, I will show results from the Green River anticline in the northern Paradox Basin, where 3D seismic reflection data were collected to image complexly deformed interbedded siliciclastic and evaporite layers of the Paradox Formation that are targets for unconventional energy exploration. By applying kinematic and numerical (discrete element) mechanical modeling techniques, the role of mechanical layer thickness and strength contrast in dictating the structural style of deformation of these layered sequences can be interrogated and used to reduce uncertainty in the interpretation of faults and folds in this subsurface application. In a second case study, I will show how field observations of fractures can be compared with numerical (boundary element) mechanical models to investigate the nature of the state of stress and failure in the sandstones that overlie the Paradox Formation adjacent to the Salt Valley salt wall. The detailed approach to data collection and model development employed in this case study permits both improved understanding of the nature of stress field variability around salt structures and within adjacent rock masses, and also provides a useful evaluation of this type of modeling approach so that it can be applied more confidently in analogous subsurface applications where data are less abundant. In both cases, the detailed collection and interpretation of geological and geophysical data and construction of models tailored specifically to the geologic circumstances allow for development of an internally consistent framework that improves understanding of the underlying structural processes and reduces uncertainty in the interpretations needed for subsurface applications.

Session

Societal relevance of structural geology and tectonics