Comparison of subsidence at Wairakei, Broadlands and Kawerau fields, New Zealand
Exploitation has caused over 9 m of subsidence at Wairakei since 1950, up to 30 cm at Broadlands between 1968 and 1974, and up to 25 cm at Kawerau since 1970. Despite these differences and large differences in the rate and amount of mass withdrawal, there are similarities in the pattern of subsidence at all 3 fields. In each field, pressure drawdown in the production zone can be identified as a nearly circular area of consolidation centered on the production borefield. The circular shape suggests that the predominant fault direction may not be the main factor controlling horizontal permeability. In addition to production zone consolidation, each field has a small area of relatively intense subsidence originating from shallow depth. The area of shallow consolidation is near to the natural outflow zone where geothermal water originally rose to near-surface and dispersed in highly compressible formations. Early identification of such areas in other fields is important because the high rate of consolidation at shallow depth can cause large horizontal strain and tilt of the ground surface. There is also evidence of cool groundwater inflow near the area of shallow consolidation in all three fields. Shallow reinjection into these areas may mitigate the effects of subsidence and groundwater invasion.
- Research Organization:
- Department of Scientific and Industrial Research, Wairakei, New Zealand
- OSTI ID:
- 7369536
- Report Number(s):
- SGP-TR-60; CONF-821214-26; ON: DE83015865
- Resource Relation:
- Conference: 8. geothermal reservoir engineering workshop, Stanford, CA, USA, 14 Dec 1982; Related Information: In: Proceedings of the eighth workshop on geothermal-reservoir engineering, by
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BROADLANDS GEOTHERMAL FIELD
GROUND SUBSIDENCE
KAWERAU GEOTHERMAL FIELD
WAIRAKEI GEOTHERMAL FIELD
FLUID WITHDRAWAL
GEOLOGIC FAULTS
GROUND WATER
REINJECTION
GEOLOGIC STRUCTURES
GEOTHERMAL FIELDS
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
WATER
Geothermal Legacy
150600* - Geothermal Energy- Environmental Aspects