Reinjection scheme in Momotombo, Nicaragua, on the basis of reservoir pressure monitoring, tracer test analysis and numerical modeling study

Reinjecting separated water back into the formation is one of the most important tasks for field management in the Momotombo geothermal field. A reinjection scheme has been operated in Momotombo since 1983. Most of the separated water, however, had been discharged to Managua Lake until 1999. The reinjection scheme was developed on the basis of the results of reservoir pressure monitoring, tracer test analysis and numerical simulation studies. Then improved reinjection scheme was initiated by Ormat in 1999. Tracer test analysis suggests that the southeastern part of the well field where reinjection wells locate is the most suitable area for injection. Shallow reinjection well RMT15 is strongly connected to the production zone, and thus cooling of the production zone due to injection in this well is expected. Numerical simulation studies suggests that steam production and enthalpy of the produced fluid in most of the production wells decline quickly by increasing steam production and injection rate in Well RMT15. If brine production increases, reinjection in RMT15 must be stopped and brine must be injected to the southeastern part of the field.