Fracture Identification and Analysis of the Arbuckle and Mississippi Reservoirs: an example from Osage County, NE Oklahoma

Olubunmi Elebiju1,   Shane E. Matson2,   Ha T. Mai3

¹Oklahoma University , ²Spyglass Energy Group, LLC , ³Oklahoma University

For the last decade, independent operators have used conventional interpretation methodology from 3-D seismic data to map Mid-Continent carbonate reservoirs. Increasingly, volumetric seismic attributes such as coherence, curvature, and amplitude gradients calculated from the 3-D seismic data are being incorporated into the Mid-Continent exploration workflow to better characterize subtle carbonate features such as karsting, tectonic faulting and fracturing, and hydrothermal dissolution, that are difficult to image from standard 3-D seismic data alone.

We present the results of seismic data analysis of several 3-D seismic surveys acquired in Osage County, Oklahoma focusing on Ordovician dolomite and Mississippian limestone and chert reservoirs which are typically classified as fracture-controlled karst reservoirs that have been diagenetically altered by tectonic faulting and fracturing, subaerial exposure, and hydrothermal alteration processes. We employed the use of geometric seismic attributes to identify fault and fracture distribution within these reservoirs that cannot be seen in more conventional 3-D single trace seismic attributes.

Arbuckle and Mississippi features imaged on coherence and most-positive and most-negative curvature geometric attribute volumes display unique polygonal features and oriented lineaments resulting from regional tectonic overprint and localized structures and flexures over cockpit karst topography. Rose diagrams of fracture length and azimuth calculated from geometric attribute horizon slices show the spatial variation of fracture density and orientation.

Initial results from the Osage County suggest that basement structure and paleo-topography of the Arbuckle dolomite plays a role in the distribution and fracturing of some of the lineaments seen in Ordovician and Mississippian reservoirs.

AAPG Search and Discover Article #90097 © 2009 Tulsa Geological Society, Tulsa, Oklahoma

 

 

���������������������������������������������������������������������������������������������������������������������� �������������������������������������������������������������������������������������������������������������������������������