Reassessment of the production capacity of two geothermal fields in Nicaragua

Abstract

In this study the production capacity of two geothermal fields in Nicaragua is re-evaluated based on exploration and drilling data collected after the publication of the Nicaraguan Geothermal Master Plan in 2001. The geothermal fields re-evaluated using the volumetric method with Monte Carlo simulation are the Casita – San Cristobal and San Jacinto – Tizate fields. Considerable new surface exploration data are available from the Casita-San Cristobal area; and several deep production and reinjection wells have been drilled in the San Jacinto – Tizate area. The volumetric model for the Casita – San Cristóbal area predicts, with 90% confidence that the estimated power production is in the range of 53-188 MW for 25 years and the cumulative probability distribution shows there is a 90% probability that the resource capacity is at least 70 MW. The volumetric model for San Jacinto – Tizate area predicts with 90% confidence that the estimated power production is in the range of 91-237 MW for 25 years and the cumulative probability distribution shows there is a 90% probability that the resource capacity is at least 100 MW. Comparison of results with the master plan shows that estimates for the San Jacinto – Tizate geothermal field are similar although the current estimate for the Casita – San Cristóbal geothermal field are lower due to the values assigned to the most sensitive parameters in the calculation, such as the reservoir area, the recovery factor, the thickness of the reservoir and the reservoir temperature. This shows the importance of methods used to assign values for the parameters; conservative or optimistic methods will greatly affect the results of the estimated power capacity.