Diagenesis in carbonate reservoirs: from conceptual to numerical modelling in the prediction of dolomitization distribution

The application of reactive transport modelling (RTM) to cases of dolomitization allows to test and select the more realistic interpretation and to predict the lateral extension of the dolomite bodies (potential hydrocarbon reservoir) in the subsurface. We present the results of RTM simulations of three different dolomitization models. The first case reproduced and evaluated the "compaction driven" model in a drowned paleohigh (Jurassic of the Southern Alps): the simulation demonstrated that the main limiting constraint is the ratio between the volume of fluids (from the basin) and that of the paleohigh. Two synsedimentary dolomitization processes ("thermal convection" and "mesohaline reflux") were tested in a model of an isolated carbonate bank (Paleozoic). Thermal convection was able to produce a dolomitized wedge in the bank margin of hte area. Finally the reflux model simulation proved that some dolomitization can be produced also with mesohaline sea water influx. In all the cases the final geometry of dolomite bodies was greatly affected by the permeability assumptions and presence of fractured zones.