Prediction of reservoir heterogeneity and quality: Examples and lessons from outcrop analogs from Wajid Sandstone, Saudi Arabia. 9th Middle East Geosciences Conference, GEO 2010.

This study seeks to characterize the reservoir rock heterogeneity and quality using sedimentological, statistical and geostatistical approaches. Paleozoic fluvial and shallow-marine reservoir analogs from the Wajid Sandstone at outcrop in southwest Saudi Arabia are the target for this study. The impact of depositional and post-depositional processes on porosity and permeability distribution were investigated at macro- to micro-scale. The study revealed a wide range of facies, environments, textural and compositional variations at outcrop scale. The porosity and permeability distribution show variability and complex patterns most probably reflecting different scales of depositional and diagenetic influences. The complex relations among parameters may be attributed to variable interrelationships. At the macro to meso-scale these include the meter-scale stratigraphic hierarchy, depositional cyclicity and lateral and vertical facies changes. While at micro-scale petrographic features, such as grain size, sorting, matrix and cement content and type all seem to be influential. The geostatistical porosity and permeability models show some agreement and differences which can also be attributed to the aforementioned controlling factors.