Significant volumes of heavy oil remain in carbonate reservoirs worldwide. Some of these reservoirs are good candidates for the application of thermally assisted production methods. Application of thermal processes to the carbonates poses a different challenge. In general, thermal recovery in carbonates is highly energy intensive and due to adverse wettability, lower matrix permeability, the anticipated recovery could be much lower compared to sandstone reservoirs. To assess and describe complex flow mechanisms in heavy oil carbonate reservoirs, simulation technique should be capable of modeling the impact of these processes. In a practical point of view of numerical simulation, the characteristics of carbonate rocks, thermal properties of carbonate rocks, spontaneous thermal processes, and key parameters in dual permeability simulation were briefly reviewed. In order to capture complex flow mechanisms of heavy oil carbonate reservoirs in numerical simulation, a dual permeability formulation is essential and the key parameters of fluid flow between matrix and fracture systems like shape factor and fracture spacing should be considered.