Modelling the Effects of Seasonal Variations in Rainfall and Production Upon the Aquifer and Surface Features of Rotorua Geothermal Field

摘要

The Rotorua geothermal field is a shallow geothermal reservoir lying directly beneath the Rotorua city in New Zealand. It is renowned for its abundance of natural geothermal manifestations including the geysers and hot springs at Whakarewarewa. Intensive extraction of the geothermal fluid in the 1970s led to a general decline of the activity of the surface features. In 1982 an extensive Monitoring Programme was initiated to provide insight into the system behaviour and response to geothermal production. Its conclusions led to the 1986 Wellbore Closure Programme that resulted in the recovery of reservoir pressures and many of the surface features. The monitoring programme continues through to the current day and efforts to provide a robust numerical model of the geothermal aquifer and surface features are ongoing. Annual and seasonal variations impacting the state of the field (e.g. production and reinjection rates, precipitation) have been included in University of Auckland (UOA) models: UOA Annual and UOA Seasonal. The results show the inclusion of these effects in the model is important for accurately representing the complexity of the Rotorua system and thus making the model useful for assisting with sustainable management of the resource.