GNS Science Consultancy Report 2006/0XX

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Figure 16. Abandoned hydrocarbon wells in Taranaki (squares) that may be converted for geothermal use. All plotted abandoned hydrocarbon wells have estimated bottom hole temperatures (BHT) >120 o C and depths from 3131 – 5064m. GNS Science Report 2007/23 22
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. GNS Science Report 2007/23 23
Page 2 and 3: Abandoned oil and gas wells - a rec
Page 4 and 5: CONTENTS ABSTRACT..................
Page 6 and 7: ABSTRACT There are 349 abandoned on
Page 8 and 9: Figure 1. Temperature, depth and pe
Page 10 and 11: 2.0 ABANDONED OIL AND GAS WELLS IN
Page 12 and 13: Figure 5. Map showing the distribut
Page 14 and 15: Figure 6. Drilled vertical depths o
Page 16 and 17: Figure 8. Temperatures ranges of on
Page 18 and 19: Table 1. Number of wells within a r
Page 20 and 21: 3.3 REASONS FOR ABANDONING WELLS Mo
Page 22 and 23: Assuming a flow of 4 L s -1 , the 2
Page 24 and 25: 5.0 CURRENT GEOTHERMAL USE OF ABAND
Page 26 and 27: In New Zealand temperature may be p
Page 30 and 31: 10. Determine how geothermal produc
Page 32 and 33: Isaac M J, Herzer R H, Brook F J an
Page 34 and 35: APPENDIX 1 NOTES ON THE GEOTHERMAL
Page 36 and 37: Speaker Company/Agency Topic Main P
Page 38 and 39: Table 6. Basic well data for onshor
Page 40 and 41: Well Name NORTH ISLAND TARANAKI Dat
Page 42 and 43: Well Name SOUTH ISLAND WEST COAST D

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