Hydrothermal dolomitization: simulation by reaction transport modelling

Abstract

Abstract Reaction transport modelling (RTM) has been successfully used to simulate dolomitization and to predict the lateral extension of dolomitized bodies as potential hydrocarbon reservoirs in the subsurface as well as to give insights into the dolomitization process itself. Geological configurations that have been tested include reflux dolomitization, thermal convection and dolomitization in compactional burial settings. In this study the hydrothermal dolomitization model has been tested with a RTM approach where a limestone reservoir in an intermediate burial setting is fluxed in the presence of deep feeding faults. Hydrothermal fluids migrate upwards from the deep basin areas through extensional fault conduits reaching more permeable levels in the reservoir. The fluids enter the primary interparticle porosity and dolomitize the limestone creating moldic and vuggy porosity. The simulations demonstrate the importance of faulting in this dolomitization process. An effective control on dolomitization is thus exerted by the permeability distribution. Moreover, the type and reactivity of the fluids entering the limestone reservoir exert important controls on the extent of the dolomite bodies.