Seismic and sequence stratigraphy of Late Jurassic in Nasiriyah oil-field

The study scope has focused on the Late Jurassic Group: the three genetically related Najmah, Gotnia, and Sulaiy formations beneath an area of more than 40000 Km2 capitalizing on huge integrated 3-D, 2-D seismic and well data compiled with competent previous regional studies and foreign literatures related, to get the utmost understanding, where, each of which, is related to each other, genetically and depositional. The study has summarized the story of the development and deterioration of the three that made up the Late Jurassic succession. Accordingly, this study, based on sequence and seismic sequence stratigraphy, has proceeded and achieved some substantial successes, the most notable ones being the identification of the optimum-Najmah reservoir quality facies throughout the Oil Province. The study has determined some proposed optimum well locations to hit the predicted optimum Najmah facies. On the Basrah basin sub-basinwestern margin, it has been interpreted that the shallow water dolomitic limestones of Najmah Formation are predominant and are unconformable overlain by Very Early Cretaceous Sulaiy due to Pre-cretaceous erosion where Sulaiy overlie the last Najmah-SB above the Najmah MFS-J70 (the unconformity part of the SB=the cropped out part of the SB)and due to Gotnia Formation wedges out towards the same margin, while the Najmah Formation time-correlated, deep water limestones-Naokalekan Formation is conformably overlain by the same evaporates where Gotnia Formation directly overlie the submerged SB-part (i.e., conformable conformity =CC). Furthermore, the study has proved that the former stratigraphic relation aspects are true for the rest of the Iraqi areas in addition to the Basrah basin-western margin.