Using Seismic Attributes to Unravel Complex Fault Tectonics in the Fort Worth Basin
Hao Guo, Charlotte Sullivan, Kurt Marfurt, and Michael Murphy
University of Houston, Houston, TX
Although faults within the subsurface of the Fort Worth Basin have been interpreted as normal, reverse, and wrench, there are few data to support specific direction of lateral motion. We use multi-trace seismic attributes of coherence, dip azimuth, and various volumetric curvatures to unravel subtle complexity and to determine presence and timing of oblique slip in one area of intersecting faults. Structural mapping of conventional seismic data in the northern Fort Worth Basin reveals that basement-involved faults cut Pennsylvanian strata, have normal dip-slip along part of their length, and strike northeast-southwest. Lineament sets observed in curvature attribute volumes strike northeast and northwest and generally coincide with the azimuth of induced fractures and natural fractures observed in resistivity-based image logs. Although compound attribute volumes image Pennsylvanian post-Atoka lineaments that appear to show left lateral offset, no conclusive piercing points have yet been identified on the major faults. We identify left-lateral separation of two sets of linear features along one of the major faults and a narrow suspected-pull-apart graben. The separation on each set of linear features is roughly equal to the long axis of the suspected pull-apart graben. This major fault system is temporally interpreted as a left-lateral wrench fault.