Summary
Chert is an unconventional reservoir rock that has been developed successfully in west Texas, Oklahoma, California and Canada. Tripolitic chert is a diagenetically altered form of cherts which show high porosity and low resistivity. The Mississippian tripolitic chert is currently an exploration and development objective through-out southern Kansas and northern Oklahoma, including our survey area of Osage county. As one of the most fully developed unconventional plays in North America, knowing the orientation and intensity of the present day horizontal stress direction is critical to both the placement and completion of horizontal wells. In our study, we wish to determine the correlation, if any, between structural deformation as measured by curvature and coherence and the present day stress orientation as measured by amplitude vs. azimuth (AVAz) analysis.
We map structural features along top Mississippian Lime horizon using geometric attributes and find a high correlation between low coherence and most negative curvature fault lineament. We migrate our data into azimuthal bins and compute changes in amplitude with azimuth. Such AVAz volumes are commonly used to predict the orientation of horizontal stress.
Faults are known to modify the subsurface stress regime. We map faults using both the strike and magnitude of the mostnegative principal curvature and visually correlate them to strike and magnitude of AVAz. To quantify this correlation, we compute a vector correlation between AVAz and most negative curvature, and find high correlation between structural faults and low anisotropy intensity indicating that the Mississippian Lime are most controlled by diagenetically altered fractures.
