The Upper Cretaceous Karababa and Karaboğaz Formations of the northern Arabian Plate include units of organic-rich and organic-lean carbonates. The Karababa A Member and Karaboğaz Formation are represented by organic-rich mudstones and wackestones. The Karababa B and C Members consist of organic-lean dolomitic wackestones, wackestones, and packstones. These formations are composed of between 35% to 100% calcite, and 14% to 28% dolomite. Measured total organic carbon (TOC) contents of organic-rich source rocks of the formations range from 1.03 to 7.82 wt. %, and calculated vitrinite reflection maturity values range from 0.48% to 0.91%. The maturity data demonstrate that organic-rich levels of these formations occur in the immature, early mature, and mature oil generation windows. Oil saturation index (OSI) threshold has been optimized as 100 oil/g TOC to early mature levels and 60 mg oil/g TOC to mature levels since the sorption coefficient varies widely as a function of thermal stress. Both OSI values and corrected OSI (OSI_c) values of the immature and early mature organic-rich (source rocks) and organic-lean (tight reservoirs) of the Karababa and Karaboğaz Formations are below the 100 mg oil/g TOC, which indicates that unconventional commercial fluid phase oil production is not probable. Many OSI values and nearly all OSI_c values of the mature source rocks and tight reservoirs exceed the 60 mg oil/g TOC, indicating potential presence of producible fluid phase oil. The maximum OSI_c values of the organic-rich (the Karaboğaz Formation and Karababa A Member) and organic-lean carbonates (Karababa B and C Members) have been calculated as 231.7 and 368.6 mg oil/g TOC, respectively. However, modeled fluid oil saturations exhibit lower values.