Simulation of Pressure Response in Geothermal Reservoirs by an Updated Lumped Parameter Method – Hjalteyri Case Study

Abstract

Lumped parameter modeling of pressure response data has been applied to many low-temperature geothermal reservoirs in Iceland as well as worldwide. This method simulates the pressure response of a reservoir by using a small number (less than 10) of linearly connected, homogenous (or lumped) volumes. The method, therefore, requires very little computing time compared to more detailed numerical modeling. The method has proved to be very successful in predicting pressure changes and has been applied as a tool for resource assessment and management in production fields for more than four decades. The presently implemented method is limited to a single source of production and has a limited number of connections between reservoir volumes. Increasing hot water consumption in Iceland over the last decades has led to increased production from geothermal fields, and an increased number of wells per field. Hence, the increased complexity of reservoir geometry calls for the enhancement of the general lumped parameter method presented in 1989. We present the results of the updated method, using Hjalteyri in Eyjafjordur, N-Iceland, as a case study.