The Late Cretaceous X Reservoir petrophysics properties and its Oil Geochemistry in the Nameless Oilfield, Mesopotamian Basin, South Iraq

The X Formation, which dates from the Late Cenomanian to the early Turonian, is the largest carbonate reservoir in Iraq's South Mesopotamian Basin. There are two shallowing-up depositional periods in it, which begin with deep water mudstone associated with wackestone, which gradually shallows into rudist and is dominated by big foraminifera shoals and barriers, which are followed by lagoonal and intertidal facies. The identification of five distinct reservoir rock types, including mB2, mB1, CRII, mA, and CRI, was based on a combination of sediment types and diagenetic processes that influenced porosity types. The formation oil geochemical studies point to a Lower Cretaceous marine carbonate source depositional environment that is early mature and anoxic.