GNS Science Consultancy Report 2006/0XX

Table 4. Proposed wells for 200 kWe pilot geothermal plant in Taranaki. Refer to Appendix 3 for well details.
BHT= bottom hole temperature.
Well
Priority
Estimated
kWe
Tipoka-1 1 240
Te Kiri-1 2 260
Toko-1 3 250
New Plymouth-
2
4 290
Inglewood-1 5 275
Comments
Tipoka-1 fluids (BHT= 142 o C at 4360m) can be reinjected in Tipoka-2,
1.1 km away, which has BHT= 88 o C at 2504m. Power can be used by
nearby dairy farms.
Well (154 o C at 4710m) near dairy farms associated with Fonterra.
There may be a need to drill a nearby reinjection well
Fluids from Toko-1 with BHT=150 o C at 4900m can be reinjected into
Toko-2 with BHT = 103 o C at 3200m, 1.2km away. There is a seal
between the Mangahewa Fm in Toko-1 and the shallower Tikorangi
Fm in Toko-2. Power can be used for Stratford. Other wells near
Stratford that can be used for power generation are: Wharehuia-1
(114 o C at 3595m) with fluids reinjected into Piakau-1 1.0km away or
Waihapa-1 (144 o C at 4942m) using Waihapa-2, 1.8km away, as a
reinjection well
Highest BHT of all onshore wells at 172 o C; located in middle of New
Plymouth. Fluids can be reinjected in numerous adjacent abandoned
wells. This was drilled before 1980 and the state of the casings and
grouts is unknown.
BHT= 164 o C at 5061m. This was drilled before 1980. There may be a
need to drill a nearby reinjection well. The nearest abandoned well
that could be used for reinjection is Ngatoro-1 about 2.1km away.
Power can be used by Inglewood. Another well near Inglewood is
Manganui-1 (131 o C at 3753m) with Tauteka-1, 830m away, as a
reinjection well
7.0 RECOMMENDATIONS FOR FUTURE WORK
This is merely a reconnaissance study whose main goal is to present an idea and the basic
data of wells that could be used for geothermal energy purposes. Before any wells could be
used the following studies should be done:
1. Review all literature on wells regarding water reservoirs, fault and stratigraphic
permeability, stratigraphic connectivity among abandoned and actively-producing wells,
downhole pressure and temperature measurements and geology.
2. Determine the state of the casing/tubings, liners and cementing jobs of selected wells.
3. Determine the corrosion state of the well pipes.
4. Measure downhole temperatures of selected wells.
5. Determine flow rates of well discharges and methods of stimulating water flow.
6. Find out if hydrofracturing is necessary or possible to enhance permeability.
7. Find out the maximum working temperatures of down hole pumps.
8. Determine fluid discharge chemistry to find out if a hybrid plants can be used to tap both
gas and geothermal fluids, predict fouling problems to the plant, determine ways of
disposing well fluids (use a reinjection well or dispose fluids into the waterways).
9. Determine fluid pathways and temperatures using petrological and geochemical
methods.
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