The commercial production of geothermal energy from sedimentary rock formations with relatively low permeability could expand the current geothermal energy resources toward new regions in the U.S. The feasibility of commercial geothermal production from sedimentary reservoirs can be studied using numerical reservoir modeling, which allows studying different well configurations and productivity enhancement techniques. In this paper we present the validation of a numerical reservoir model with respect to an analytical model, and the process followed to achieve an acceptable match between the numerical and analytical solutions. The analytical model used is based on the work of Gringarten (1978), which consists of a conceptual sedimentary geothermal reservoir model, considering an injection and production well doublet in a homogeneous reservoir. The numerical modeling is conducted using a commercial thermal reservoir simulator. In order to reproduce the analytical model results, the numerical simulation model is modified to include the same assumptions of the analytical model. The following model parameters are considered to obtain an acceptable match between the numerical and analytical solutions: grid block size, time step and reservoir areal dimensions; the latter related to boundary effects on the numerical solution. Here we present lessons learnt and guidelines to improve the numerical simulation solutions. The agreement between the numerical and analytical models allows us to proceed with confidence to study reservoir enhancement techniques using numerical reservoir simulation. The validated numerical reservoir model is used to compare the performance of the geothermal system with and without enhancement treatments (e.g., hydraulic fracturing).

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