CONCEPTUAL AND LUMPED-PARAMETER MODELS OF GEOTHERMAL RESERVOIRS.

Lumped-parameter modeling (material balance coupled with water influx) is used to match geothermal reservoir production data, and to predict future pressure decline. The future should not be predicted for a longer period than there is production history. The main use of such modeling to field development is to estimate when make-up wells need to be drilled, and what effect an increased fluid production rate (additional power unit) would have on reservoir drawdown. Lumped-parameter modeling can provide reliable answers to such questions early on in the development of geothermal fields. The lumped-parameter approach is based on having elementary production data, such as cumulative mass production and the associated reservoir pressure decline. As further data become available, the more detailed distributed-parameter (numerical simulation) approach can be applied. Refs.