Lithology and Geochemistry of the Chert Beds in the Qulqula Radiolarian Formation From Zalan and Kaolos Sections NE-Iraq

Conventional well-logging methods are crucial for detecting petrophysical properties and are instrumental in reservoir characterization, particularly when subsurface rock samples are unavailable. In this study, log data and thin sections were employed to determine the petrophysical properties of the Late Campanian-Maastrichtian Shiranish Formation in the Kirkuk and Dukan area, Kurdistan Region, Iraq. Various approaches were integrated, including the Neutron-Density crossplot for lithology identification, Gamma-ray logs for determining shale volume, and sonic, density, and neutron logs for assessing porosity. The Shiranish Formation exhibits poor to fair porosity, with average values reaching 11.12% from the sonic log, 6.8% from the density log, and 8.4% from the neutron porosity log. Lithologies identified from the Neutron-Density crossplot indicate that the Shiranish Formation is predominantly composed of limestone and marly limestone. The determined shale volume within the examined interval reveals a high level of clay constituents in the lower part of the formation (2655 m-2693 m). The reservoir quality of the Shiranish Formation in the outcrop section is negligible, as evidenced by the thin section samples used in this study.