Mid-Continent Section

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3D seismic evidence for strike-slip faults in Kansas


Interpretation of a set of 3D seismic volumes totaling 120 mi2 (311 km2) substantiates strike-slip faulting in the Hugoton Embayment in southwest Kansas. The seismic data was used to assess the potential for CO2-EOR in Chester and Morrow sandstone reservoirs in four fields including Pleasant Prairie, Eubank, Cutter, and Shuck. The fields lie on or adjacent to horst blocks that are each bounded by a large reverse fault that may also be part of a flower structure, a radiating pattern of faulting that is diagnostic of strike-slip motion. The horsts are also accompanied by karst features aligned on lineaments crossing the horsts. Seismic indicates the lineaments are due to fractures and disturbed amplitude correlations that span the Mississippian strata into the Lower Ordovician Arbuckle Group. The bounding faults bend around the horst blocks and are considered to be restraining bends along the strike slip fault. Normal faults and fracture zones occur on the side opposite to the bounding fault indicating extension, a feature common to a restraining bend. In the area immediately south of Shuck Field seismic time and isochron maps indicate a minimum of 2 miles (3.2 km), perhaps up to a maximum of 4 mi (6.4 km) of lateral offset of a bounding fault. The timing of the primary tectonic movement is Morrow-Atokan, but seismic data reveals thinning extended movement across the bounding faults, indicating that the structures were active for considerable amount of time.