It should be noted, though, that only rarely have the conglomerates been the primary objective of a well and exploration efforts have not focused on this formation. Since the producing characteristics are similar, this study combines the two zones for statistical purposes. Most of the Mississippian fields in the county produce from the Chappel member of the Osage series. It is a fractured, often vugular carbonate and dolomitic in the best fields. Permeability is very high, sometimes immeasurable due to the heavy fracturing and voids but buildup tests on some of the better reservoirs show permeability in the 6 md range.
Gas is vented in many of the fields.
Earlier completions were conventional perforated casing type but Primary cement job problems coupled with later channeling and early water breakthrough has led many operators to drill just a few feet into the top of the porosity, set casing and complete open hole. This approach appears to help but it may bypass deeper oil, limits what can be done if water coning does develop, and certainly makes determination of reservoir size difficult or impossible. The oil gravity averages 44.3 API with a 37 to 54 range. A few crudes have properties resembling volatile oil. Many of the better wells, however, show no decline because of the highly effective water drive.