Comparison of subsidence at Wairakei, Broadlands and Kawerau fields, New Zealand

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:7369536

Allis, R G

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
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150600* -- Geothermal Energy-- Environmental Aspects
BROADLANDS GEOTHERMAL FIELD
FLUID WITHDRAWAL
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
GEOTHERMAL FIELDS
GROUND SUBSIDENCE
GROUND WATER
Geothermal Legacy
HYDROGEN COMPOUNDS
KAWERAU GEOTHERMAL FIELD
OXYGEN COMPOUNDS
REINJECTION
WAIRAKEI GEOTHERMAL FIELD
WATER