Subsurface relations of the Albian rocks in southern Iraq are postulated from the study of lithofacies, electrical well logs, petroleum occurrences, geothermal source rocks maturation, and hydrogeologic mapping.

From these studies an evaluation of the commercial potential for oil in the Nahr Umr Formation became feasible.

It appears that a petroliferous belt exists in the marine-marginal facies of the lower Albian Nahr Umr sandstone. The oil in the Nahr Umr reservoirs has probably been generated in deep Lower Cretaceous source rocks, and may have started to generate as early as Paleocene time.

The upper shale beds of the Nahr Umr Formation supersedes the Ahmadi Shale Formation, which acts as a cap rock to the Albian reservoirs in Kuwait and Neutral Zone. Hitherto, no economic oil trap has been discovered in the upper Albian Mauddud Formation that overlies the Nahr Umr and underlies the Ahmadi in southern Iraq.