S013-0002
3D Structural Analysis and Seismogenic Association in the Central Delaware Basin, West Texas

Tuesday, 8 December 2020
Poster
Elizabeth Horne1, Peter Hennings1, Alexandros Savvaidis1, Alan P Morris2, Scott James Staniewicz3 and Jingyi Chen4, (1)University of Texas at Austin, Bureau of Economic Geology, Austin, TX, United States, (2)Alan Morris Consulting, Department of Earth, Material, and Planetary Sciences, Traverse City, MI, United States, (3)University of Texas Austin, Austin, TX, United States, (4)University of Texas at Austin, Aerospace Engineering & Engineering Mechanics, Austin, TX, United States
Abstract:
The Permian Basin of Texas and New Mexico is an important petroleum province with a complex tectonic history, as this region has been shaped by several major deformation events since the Proterozoic. Similar to other petroleum basins within the midcontinent, the Delaware Basin has experienced an increased number of earthquakes beginning in 2009 and accelerating from 2016 through to present. Many of these recent earthquakes have been spatiotemporally linked to hydraulic fracturing and disposal of oilfield wastewater at multiple subsurface levels. However, the identification and characterization of earthquake hosting faults has remained elusive. This research associates the geometric characteristics and stress state of fault surfaces interpreted from 3D seismic with nearby well-located earthquake events to determine which of these surfaces are associated with earthquakes.

We focus on the Grisham Fault zone (GFZ) in the central Delaware Basin. The GFZ is an E-W trending oblique-transpressional fault zone that bisects the Delaware Basin. Detailed mapping of a 460 km2 3D post-stack depth seismic reflection survey provides key seismic-stratigraphic horizons, fault surface extents, fault-horizon offset, and key tectonostratigraphic patterns that provide evidence for fault growth and linkage evolution. There are 2 levels of faults within the dataset, including basement-rooted (BR, 60% of total trace length) that cut up into deeper Permian strata and shallow rootless (SR, 40% of total trace length) that cut from near-surface down to shallower Permian strata. The BR faults are high-angle reverse and oblique-transpressional, and strike ENE and NNE, respectively. The RS faults are extensional, linear, parallel, strike NE, and are decoupled vertically from BR faults.

A regional stress model based on published and new inputs is used calculate the static stress state for faults of both levels. The SR faults are optimally oriented for slip. The BR faults range from stable to critical. Integration with well-located TexNet earthquakes shows that several of the BR faults are seismogenic. Integration with the earthquakes, fault plane solutions, and InSAR ground surface deformations demonstrate that the SR faults are neotectonically active, and perhaps anthropogenic.

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