Geophysical Monitoring During Exploitation of the Broadlands (Ohaaki) Geothermal Field

Abstract

Monitoring physical changes which accompany exploitation of a geothermal field can provide useful information about the response of the reservoir to production and injection, and so contribute to rational, economical, field management. Monitoring can also assist management of the field to minimise any adverse environmental effects caused by At Broadlands, repeated microgravity surveys could be used to determine mass recharge, changes in the steam zone; test reservoir simulation models. Repeated electrical resistivity measurements may allow changes, with time, in the position of the field boundary to be detected. Levelling can provide about any ground, Airborne infrared data, ground temperature measurements, and observationsof thermal features would allow changes in to be monitored. Measurement of water changes in shallow wells can provide information about the response of the groundwater system to exploitation of the reservoir. A network of seismometers will detect any exploitation induced- In most cases, sufficicnt measurements have already been made for natural changes to be distinguished from exploitation induced changes.