Field-scale simulation of matrix-fracture interactions

Simulation of flow in fractured media continues to be among the most challenging problems faced in geothermal reservoir engineering. Because of a lack of information regarding specific matrix-fracture characteristics (e.g., fracture distribution, spacing, and aperture, and interfacial area for exchange of fluid), explicit representation of the reservoir is generally not feasible. Instead, a multiple (but usually dual) continua model is used. In multiple continua models, specific details of the reservoir are replaced with averaged properties (average fracture spacing, for example). Such averaging facilitates the simulation of fractured reservoirs; however, field-scale simulation remains numerically intensive. For example, it has been stated that 5-10 nested shells are required in the Multiple Interacting Continua formulation in order to adequately resolve transient pressure and saturation gradients between the fracture and matrix domains. While this results in a large amount of additional work (compared with a single porosity system of the same dimension), it should be noted that the MINC method is capable of resolving such transients, whereas most dual porosity simulators cannot