Sedimentological and Lithofacies Analysis of the Fluvial Cambro-Ordovician Saq Formation: Reservoir Analog Study, Saudi Arabia

Summary The outcropping strata of the Saq Formation in Central Saudi Arabia represent an excellent analog for the Cambro-Ordovician fluvial system. The Saq Formation is not only representing significant hydrocarbons reservoir in the subsurface but also recently gained importance as groundwater aquifer. This study presents quantitative and qualitative sedimentological data that could significantly enhance the understanding of the Saq Formation and the Paleozoic fluvial systems. The studied outcrops are about 40 m thick, were logged in detail, and around 150 samples were collected for microfacies analysis. Six lithofacies types were recognized within the Saq Formation in the study area that making up the bulk of the stratigraphy. Grains are mostly well sorted and rounded to subrounded quartz grains. The succession is composed dominantly of fining-upward sets, ranging in thickness from 10 to 20 cm. The later reflect deposition from a mature braided fluvial system. The main channel has a total width of about 1500 m, with a complex amalgamation of sub-channels. The results of this study provide qualitative and quantitative data that enhances the understanding of the Saq Formation and will improve geological modeling and fluid flow simulations of these reservoirs. This study, therefore, helps to understand the Cambro-Ordovician fluvial system.