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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


GeoGulf Transactions
Vol. 71 (2021), Pages 185-191

3D Interpretation, Structural Characterization, and Seismogenic Association of Faults in the Eagle Ford Region, South-Central Texas

C. McKeighan, P. Hennings, E. Horne, K. Smye

Abstract

There is a well-known occurrence of increased felt Previous HitseismicityNext Hit and smaller seismic events in areas where oil field operations, such as wastewater disposal and hydraulic fracturing operations occur. The Eagle Ford shale play of south-central Texas has experienced an increase in the rate of felt Previous HitseismicityNext Hit from 2014–2019, temporally coincident with petroleum development in the region. By mid–2019, the rate of Previous HitseismicityTop decreased alongside the reduction of well completions, thus prompting the drive to better understand the relationship between hydraulic fracturing operations and geologic conditions that contribute to the evolving hazard of this region.

This work aims to map and geomechanically characterize faults that delineate seismogenic regions, such as the Karnes fault zone, and aseismogenic regions of the Eagle Ford. A regional, integrated data set composed of published data, wells, earthquakes, and interpretations from operators provides input for a 3D structural framework. For fault mapping, key stratigraphic intervals have been mapped, fault segments identified from publications were validated and enhanced, 3D fault segment interpretations were integrated, and new faults were interpreted from vertical deviations in horizontal wells. Additionally, centroid moment tensors and well located earthquakes provide insights into earthquakes that are linearly distributed along fault planes and enable identification of active seismogenic faults.

Faulting mapped across the Eagle Ford trend is dominated by NE–SW striking normal faults, regional faults dipping towards the SE, and counter-regional faults dipping towards the NW. At least five locations are identified in the region that connects earthquakes to fault planes. Continued analysis will tie these earthquakes to their associated seismogenic structures and then can be assessed for their potential to be reactivated by hydraulic fracturing. Ultimately, this research will analyze how the 3D morphologic and stress state of seismogenic and aseismogenic fault systems relate to earthquakes by determining which faults are more sensitive, which faults have been seismogenic, and the uncertainties of these assessments.


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