DESCRIPTION OF THE MISSISSIPPIAN SYSTEM AND CHEROKEE GROUP IN NESS COUNTY, KANSAS USING LITHOLOGY CROSS-PLOTS

Cross-Plots that incorporate different porosity readings have been used to understand lithology of rock units. These plots play an important part in petroleum exploration by determining attributes of marker beds in the stratigraphic succession of the geographic region, and can provide insight into hydrocarbon potential within formations. A more detailed local description provides small independent companies with subsurface data to understand controlling factors of production in small, mature oil fields. This study uses a variety of lithology cross-plots to describe the Mississippian carbonate reservoir and Cherokee Group in the Oppliger Oil field in Ness County, Kansas. Available data include, a suite of petrophysical logs, limited number of geologic reports, and production history from each individual well. Several assumptions were made when producing more data to be incorporated into analysis. Production history was used to determine accuracy and validate well-log analysis assumptions.

Raw data indicated a dominate presence of silica and carbonate units. However, to accurately interpret data, petrophysical attributes of lithology identification and background knowledge of Kansas stratigraphic succession were used to correct raw data. Several lithology, mineralogy, and porosity aspects correlate with producing depth intervals in the Mississippian System. The local differences in lithology and mineralogy are the primary controls of producing carbonates in Mississippian age rocks. Porosity values within the Cherokee Group show trends associated with seal integrity and fluid presence. Results from interpretation and analysis of the lithology cross-plots show some distinct trends within the two rock units. Lithology descriptions of the Mississippian carbonates and Cherokee Group show attributes that can be used for local exploration in small, mature oil fields in western Kansas. To determine the impact that these results indicate, a large scale case study should be performed.