Erosion and Karst in Subsurface Middle Paleozoic Rocks in the Arkoma Basin, Oklahoma, USA

Seismic attribute analysis, guided by well data, reveals widespread stratigraphic anomalies caused by erosion or karstification in the late Ordovician-early Devonian Hunton Group in the Arkoma Basin, eastern Oklahoma, USA. This study shows that these strata are more extensive than previously known. Well data and seismic mapping in the Red Oak petroleum field identify approximately 40 m thick Hunton lenses, averaging 3 km in diameter, surrounded by karsted rock. These lenses may be remnants of incomplete erosion during the Middle Devonian period (pre-Woodford unconformity) or result from Hunton rocks sagging into sinkholes caused by karstification and collapse of underlying Viola or Bromide carbonates. Using formation tops from wells, correlated with attribute and structure maps from a 3D seismic volume, we identify (1) areas lacking Hunton seismic markers, indicating complete removal; (2) areas with Hunton contacts, showing where Hunton remains; and (3) zones without Hunton but with a thin layer underlying carbonate strata, interpreted as an incipient karst zone, often near areas with Hunton. We also observe that the thickness of the overlying Woodford Shale, a key hydrocarbon target, correlates with karstic and erosional thinning of Hunton carbonates. Interpretation of 3D seismic data reveals a strong connection between thinned Hunton and thickened Woodford Shale.