Reactive Transport Processes in Acid Stimulation of Carbonate Rocks

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Considering that 50-60% of the world's oil and gas reserves are contained in carbonate systems, the understanding of geomechanical and hydrodynamical regimes in these systems are essential for planning and evaluating the reservoir strategies and reducing the geological risks. The geomechanical properties of carbonate rocks in the subsurface systems are under influence of syn- or post-deformation physico-chemical diagenetic processes such as dissolution, cementation and precipitation. These processes evolve the geomechanical landscape of the rock, leading to alterations of petrophysical properties of rock such as permeability and porosity with inevitable effects on flow behaviour. For the carbonate systems the diagenesis controls fracture occurrence, architecture and attributes. This is a key factor for management of carbonate reservoirs, because the nature of carbonate systems as low-matrix-porosity hydrocarbon reservoirs, imply that these systems can be productive only when permeability is enhanced by fracture generation or faults reactivation. The diagenetic information should be incorporated into construction of more accurate geomechanical models and more realistic fracture patterns for use in the fluid-flow simulation. Moreover, the spatial and temporal scales of occurrence of the physical and chemical diagenesis at pore level and generation, propagation and/or reactivation of micro-features in the porous media, impose a multiscale problem for an integrated geomechanical-flow simulation in carbonate reservoirs. In this project the geomechanical effects of diagenesis are coupled with multiphase flow for hydrocarbon production strategy in a synthetic carbonate reservoir. Effects of pressure and temperature on precipitation and dissolution of minerals (carbonate-components) will be investigated, in coupling chemical reactions with flow. Additionally will be looked to the pore network and tomography heterogeneities and influence on chemical diagenesis and dissolution of carbonates in fractures. Software to be used: COMSOL Multiphysics (Chemical Engineering and CFD modules).