Stratigraphic Features of Impregnated Sand within the Ratawi Shale and Their Hydrocarbon Prospectivity in Bahrah, Kuwait

The lower Cretaceous reservoirs are very good producers in various structures of Kuwait. The Ratawi Formation, which is of lower Cretaceous, consists of Ratawi Limestone Member in its lower section and Ratawi Shale Member above it. The reservoirs in both have been successfully drilled in many parts of Kuwait. In Bahrah area a few wells have produced oil from the sands of the Ratawi Shale Member. These sands are discrete, thin and limited areal extent but have good porosity. Though they have the hydrocarbon potential additional efforts in terms of understanding their nature of deposition, entrapment, play, etc., are required to explore them further. The main challenges are to establish presence of thin reservoir, its geometry and distribution within thick Shale section. Sequence Stratigraphy, mapping these sands in acoustic impedance volume and using spectral decomposition, it is inferred that migratory and vertically stacked channels in Bahrah area of Kuwait deposit them. The channel course is apparently from the north to south instead of the current understanding of the northwest origin. The potential of these sands can be well realized by invoking stratigraphic play concept in exploration and development. This paper focuses on the coarser clastic deposits within Ratawi Shale Member.