Diagenesis of the Asmari Formation (Oligo-Miocene; SW Iran): Implications on Reservoir Modelling of a Giant Oilfield

This contribution refines the diagenetic evolution of the Asmari Formation (Oligocene – Early Miocene) in southwest Iran. It presents diagenetic maps providing invaluable data for assessing reservoir heterogeneities and optimising rock-typing. The major results of this work bridge the gap between classical geological study (which includes conceptual dolomitisation models, burial history and paragenesis) and the actual reservoir heterogeneity encountered in the investigated field and demonstrated by the production distribution. Diagenetic maps (Limestone %, Dolomite %, Anhydrite %, Total Porosity %, Dissolution Porosity %, Cementation %) covering six stratigraphic intervals that are bounded by key sequence stratigraphic surfaces reveal spatial and vertical distribution characteristics in the investigated oil field. Integrating these diagenetic maps shows dolomite, anhydrite, porosity and dissolution relative distribution across the study area and per stratigraphic interval, resulting in better understanding of the diagenetic processes and their products. Thus, a comprehensive, generalized diagenesis model explaining the reservoir properties evolution prior to oil charging was succeeded.