Recent petrophysical analyses of Arab D limestone identify the M_1 bimodal pore system as the most common and important member of a new set of petrophysical rock types, which uses a new pore system classification based on extensive studies of a large and comprehensive collection of mercury injection capillary pressure (MICP) data set from Ghawar Arab D. The role played by the pore system parameters describing the macropores (M) and the micropores (Type 1) within the M_1 system indicates the significant contrast in flow parameters and wettability which may have strong implication on the microscopic displacement efficiency of carbonate reservoirs dominated by these multimodal pore systems. We propose to study this system as a system consisting of multiple interacting continua. Numerically, such a system is a generalization of the classical dual porosity dual permeability system into the multiple porosity multiple permeability framework. Since the micropores have permeability which can be four orders of magnitude smaller than the macropores, it is reasonable to neglect the inter-grid flow for the microspore. However, the micropores and macropores connectivity is at the rock fabric and is expected to be substantial. Additionally, the reservoirs are also known to include fractures and super-K regions. Thus, the parallel reservoir simulator is for a general system of multiple interacting continua. The parallel numerical methods will be discussed. We performed numerical studies to examine the sensitivity of a bimodal pore system in both fractured and non-fractured scenarios and contrast these against the traditional simulation of the single-mode pore system. Simulation results and discussions of the effect of flow parameters and wettability contrasts of the bimodal system in both the non-fractured and fractured area of the reservoir will be presented.

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