AUGMENTED CIRCULAR SCANLINE METHOD: FRACTURE NETWORKS IN MISSISSIPPIAN (VISEAN) CARBONATES IN NORTHEASTERN OKLAHOMA

Characterizing fracture networks in carbonate rocks is crucial for the subsurface study of hydrocarbons, characterization of water flow in aquifers, and classification of mineral ore deposits, as fracture networks play a primary role in the control of permeability and fluid flow. This study takes advantage of the well-exposed and highly fractured outcrops of the Mississippian Reeds Spring Formation in northeast Oklahoma to analyze the heterogeneous fracture networks present.

We combine the augmented circular scanline method and areal sampling on high-resolution digital elevation models (DEMs) and orthomosaics to collect fracture attributes, such as orientation, spatial distribution, length, aperture, and intensity of fractures on bedding surfaces located in three different areas in Mayes County, Oklahoma. The fracture data collected in this study reveal that the fracture intensity, spacing, and length vary depending on the lithology and stratigraphic location. There are similarities between the regional and local orientation of joints in the area, with most of the fractures striking NE—SW. We have found that non-systematic fractured chert beds characterize the lower Reeds Spring Formation with a mean fracture intensity of 23 m/m², mean spacing of 6 cm, and mean length of 11 cm, while the limestone-dominated portions of the lower Reeds have systematic parallel joints with a mean fracture intensity of 13 m/m², mean spacing of 14 cm, and mean length of 65 cm. The products of this study have contributed to our understanding of the fracture networks in the Mississippian carbonates that make up most of northeast Oklahoma.