MAPPING MISSISSIPPIAN TRIPOLITE PODS NEAR THE MISS-PENN UNCONFORMITY FROM 3D SEISMIC DATA IN OSAGE COUNTY, OK

In Osage County, OK, Mississippian tripolitic chert ('chat') present near the Miss-Penn unconformity has been an oil exploration target for decades. Recently, modern horizontal drilling and completion methods have shown the deeper, tight Miss section to be a major unconventional resource play. However, highporosity tripolitic chert is still of interest and can be mapped in 3D seismic data. Probable tripolitic chert intervals can be seismically identified by stratigraphic position, character of the Miss-Penn unconformity, and strong negative amplitude anomalies. The amplitude anomaly occurs due to relatively low acoustic impedance (density times velocity) of the tripolite relative to basal Penn sandstone and shale. There are subtle seismic indications of tripolite at multiple levels in the Miss section.

Tripolitic Mississippian rocks occur in outcrop in NW Arkansas and surrounding areas. Morphology of chert pods as mapped in 3D seismic data may be a guide to understanding outcrop occurrence, and provide insight to Miss Lime deposition and diagenesis.