INTEGRATED DIAGENESIS AND HIGH-RESOLUTION SEQUENCE STRATIGRAPHY OF THE MISSISSIPPIAN LIME, NORTH-CENTRAL OKLAHOMA

This study uses early diagenetic fabrics as a tool to refine high-resolution sequence stratigraphic interpretations and make predictions as to the distribution of early diagenetic fabrics within reservoir facies of the Mississippian limestones of the southern Midcontinent. Diagenesis exerts a strong control on the quality and heterogeneity of carbonate reservoirs. Some diagenetic processes are directly related to the physical nature of the sediment, and the resulting geometries can be directly related to sedimentation patterns. Early marine and phreatic cementation results in occlusion of intergranular pore space, reducing porosity and creating systematic changes in petrophysical properties. Thus, identifying the distribution of different diagenetic fabrics and understanding the underlying processes creating the distributions is of fundamental importance. When these diagenetic processes are integrated with facies in a sequence stratigraphic framework they provide a predictive tool for the distribution of diagenetic alterations that constrain reservoir quality and heterogeneity. An example of this relationship is the high-chemical reactivity of carbonate sediments and the intensive diagenesis and porosity modification frequently observed at high-frequency cycle tops and sequence boundaries. A sequence stratigraphic framework has been developed for Mississippian limestones using cores drilled in north-central Oklahoma (Logan and Payne Counties). This work suggests deposition on a regionally extensive carbonate ramp to distally steepened carbonate ramp. The sequence stratigraphic hierarchy can be defined as an overall 3^rd order sequence containing 4^th order high-frequency sequences and 5^th order cycles. This study utilizes early diagenetic analysis including thin section and cathodoluminescence petrography, scanning electron microscopy, X-ray diffraction, and stable isotope geochemistry to further define the distribution of such features within the sequence stratigraphic framework. This study will support and constrain the current facies based sequence stratigraphic interpretations. Additionally, it is expected that this study will indicate that the early diagenetic heterogenetic fabrics within the Mississippian limestones can be predicted at a range of scales.