Carbonate reservoirs are typically complex, containing structural, stratigraphic, sedimentologic and diagenetic heterogeneities over a wide range of length-scales. Much of this heterogeneity cannot be resolved in seismic data, while core and wireline-log data do not provide information on heterogeneity away from the well. Consequently, it is difficult to characterize and predict the fluid flow behavior of carbonate reservoirs before and during production. Proper characterization and quantification of the reservoir properties and fluid flow dynamics of carbonate reservoirs requires a thorough and quantitative understanding of their internal 3-D stratigraphic and facies architecture, and associated diagenetic heterogeneity. This project will characterize and quantify the impact of stratigraphic, sedimentologic and diagenetic heterogeneities on flow during hydrocarbon recovery in carbonate reservoir types which are of interest to Saudi Aramco. The project will use a range of tightly constrained, detailed 3-D geological models, reconstructed directly from selected outcrop analogues capable of providing high resolution 3-D data. The models will capture the internal stratigraphic and facies architecture of the outcrop analogues, and associated diagenetic modification of petrophysical properties. The outcrop modeling and simulation work will be supplemented by subsurface studies of selected carbonate reservoirs. These will provide petrophysical properties for flow simulation studies, and calibration of the simulation model predictions against observed production behavior.