Carbonate reservoirs that contain natural fractures and matrix heterogeneities make the scaling problem from the core- or log-scale to the reservoir simulation grid challenging. Reservoir production responses with fast flow in the high conductive fracture network and slow response from the matrix, will often call for simulation models known as dual continuum models. The classical dual continuum models will either be dual porosity or dual porosity-permeability models. Historically, dual continuum models are developed to model well test single-phase pressure responses. Consequently, large limitations occur in these models when it comes to predicting oil recovery by multi-phase flow processes with both diffusive and convective forces. In such cases, the process at hand is not modeled explicitly, but treated by generic models selected and calibrated by the user. We have developed workflows and related software, “Carbonate Case Generator” to anchor dual porosity models to fine scale models while maintaining the key mechanisms of flow given fracture system and matrix heterogeneities on small scale.