Numerical simulation and production prediction assessment of Takigami geothermal reservoir

A numerical model was developed for the Takigami geothermal reservoir. A conceptual model of the field was constructed, initial and boundary conditions were defined according to available data. For the optimum model, permeability values of assigned rock types, mass flow rates, enthalpies, and locations of recharge zones were estimated according to matching between computed temperature for wells and their temperature profiles before the exploitation. Observed and calculated temperature profiles confirmed the validity of the conceptual model. The best model could successfully reproduce the initial temperature profiles of 13 wells located mainly in the production area. A developed model was used as an initial model for future prediction of the reservoir performance. The prediction simulation was conducted by assuming two different development scenarios for the Takigami geothermal power plant. Scenario I was continuing the current power production. Scenario II was to investigate producing 8.6 MWe more electricity by employing bottoming binary cycle to the currently under operation single flash plant. Effects of production and reinjection temperatures under proposed development scenarios were evaluated. Simulation results indicated that most probably there is no direct interaction between reinjection and production zones in the Takigami reservoir, and installing a binary plant will not have any severe impact on reservoir performance.