Three-dimensional modelling of a geothermal reservoir a case study of Songwe site in Mbeya area, Tanzania

Geothermal energy is a potential renewable energy source that should be taken into account by the Tanzanian government. In Tanzania, preliminary survey studies of hot springs and geothermal sites have been carried out since 1949. However, the available data is inadequate for evaluating the geothermal power potential. Traditional methods in flow measurements and visualization have limitations in geothermal reservoirs located deep underground. In this research, the use of computational fluid dynamics (CFD) technique for reservoir modelling provides an input to overcome some of these limitations by giving an insight into complex flows that are difficult and expensive or impossible to study using traditional techniques. Commercial CFD software FLUENT 12 was used for this research work. The predicted results indicate that the rate of temperature and pressure drop along the fractured hole path were about 0.02oC per meter and 0.025 bar per meter, respectively. Further, the predicted steam quality at outlet is nearly 0.95. Also the concentration of dissolved salts in the rock matrix was investigated and found that the concentration in the steam at exits is nearly the same mean concentration as the one in the rock matrix. Based on interpretation and mentioned conditions in this study, CFD technique can be utilized to shed more light in geothermal reservoirs whose flow is three-dimensional and complex.