Chemistry of the Rotorua Geothermal Field Part 3: Hydrology Confidential Client Report E K Mroczek, M K Stewart and B J Scott 2004/178
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Chemistry of the Rotorua Geothermal Field Part 3: Hydrology Confidential Client Report E K Mroczek, M K Stewart and B J Scott 2004/178 December 2004 Chemistry of the Rotorua Geothermal Field Part 3: Hydrology Prepared for ENVIRONMENT BAY OF PLENTY E K Mroczek M K Stewart B J Scott Institute of Geological & Nuclear Sciences Limited CONFIDENTIAL Client Report 2004/178 Job Number 520W1037 December 2004 COMMERCIAL IN CONFIDENCE: This report has been prepared by the Institute of Geological & Nuclear Sciences Limited exclusively for and under contract to Environment Bay of Plenty. Unless otherwise agreed in writing, all liability of the Institute to any party other than Environment Bay of Plenty, in respect of the report is expressly excluded. Confidential LIST OF CONTENTS Page EXECUTIVE SUMMARY................................................................................v 1.0 INTRODUCTION .............................................................................................1 2.0 RECENT WORK...............................................................................................3 2.1 Part 1........................................................................................................3 2.2 Part 2........................................................................................................4 3.0 TREATMENT OF CHEMICAL DATA...........................................................4 3.1 Introduction...............................................................................................4 3.2 Triangular diagrams ..................................................................................5 3.3 Geothermometers......................................................................................7 3.2 Chloride-enthalpy diagram.........................................................................7 4.0 GEOLOGICAL SETTING................................................................................8 5.0 PREVIOUS WORK...........................................................................................9 6.0 RESULTS FOR SAMPLES COLLECTED IN 2002 AND 2003..................12 6.1 Ngapuna – Government Gardens.............................................................12 6.2 Whakarewarewa.....................................................................................14 6.3 Kuirau - Ohinemutu.................................................................................17 6.4 Wells ......................................................................................................19 6.5 Enthalpy – Chloride Correlations .............................................................22 6.6 Geothermometers....................................................................................22 6.7 Gas compositions ....................................................................................24 7.0 DISCUSSION...................................................................................................27 8.0 CONCLUSIONS..............................................................................................30 9.0 RECOMMENDATIONS................................................................................31 10.0 ACKNOWLEDGEMENTS.............................................................................31 11.0 REFERENCES.................................................................................................32 © Institute of Geological & i Chemistry of the Rotorua Geothermal Nuclear Sciences Ltd Field Part 3: Hydrology Confidential Page LIST OF FIGURES Figure 1. Inferred hydrology of the Rotorua Geothermal Field..................................11 Figure 2. HCO3 (true) vs. Chloride - Ngapuna Springs Area...................................13 Figure 3. HCO3-Cl-SO4 ternary diagram - Ngapuna Springs...................................13 Figure 4. B-Cl-SO4 ternary diagram - Ngapuna Springs..........................................14 Figure 5. HCO3 (true) vs. Chloride - Whakarewarewa Springs ...............................16 Figure 6. HCO3-Cl-SO4 ternary diagram - Whakarewarewa Springs ......................16 Figure 7. B-Cl-SO4 ternary diagram - Whakarewarewa Springs..............................17 Figure 8. HCO3 (true) vs. Chloride - Kuirau-Ohinemutu Springs .............................18 Figure 9. HCO3-Cl-SO4 ternary diagram - Kuirau-Ohinemutu Springs ....................18 Figure 10. B-Cl-SO4 ternary diagram – Kuirau-Ohinemutu Springs ...........................19 Figure 11. HCO3 (true) vs. Chloride - Wells .............................................................20 Figure 12. HCO3-Cl-SO4 ternary diagram - Wells ....................................................20 Figure 13. B-Cl-SO4 ternary diagram - Wells ...........................................................21 Figure 14. Chloride-Enthalpy diagram for the sampled and proxy wells......................21 Figure 15. K-Na-Mg ternary diagram.......................................................................23 Figure 16. Ar-N2-He ternary diagram.......................................................................26 Figure 17. H2S-CH4-CO2 ternary diagram................................................................26 Figure 18. Contours of constant chloride and bicarbonate..........................................29 Figure A1. Location map of wells sampled and proxy wells........................................41 © Institute of Geological & ii Chemistry of the Rotorua Geothermal Nuclear Sciences Ltd Field Part 3: Hydrology Confidential LIST OF TABLES Page Table A1. Rotorua Geothermal Field and location of sampled and proxy wells ..............42 Table A2. Separated water chemical analyses of wells sampled in January and March 2003.................................................................................................43 Table A3. Separated steam chemical analyses of wells sampled in January and March 2003.................................................................................................44 Table A4. Well discharge water compositions for sampled and proxy wells ....................45 Table A5. Well discharge steam compositions for sampled and proxy wells....................47 Table A6. Well discharge steam compositions for sampled and proxy wells, concentration per mole dry gas......................................................................48 Table A7. Well discharge water compositions for proxy wells only.................................49 Table A8. Geothermometer temperatures and reservoir Chloride (Clres)..........................50 Table A9. Relative HCO3-Cl-B....................................................................................51 Table A10. Isotopic measurements for geothermal bores sampled in 2003 and historical data ...............................................................................................52 Table B1. Analyses of water from Pohutu Geyser, 1937-2002 ......................................56 Table B2. Analyses of water from Kuirau Lake, 1945-2002..........................................61 Table B3. Natural geothermal features sampled in April 2002........................................65 Table B4. Chemical analyses of natural features sampled in April 2002 ..........................66 Table B5. Isotopic analyses of selected natural features .................................................71 © Institute of Geological & iii Chemistry of the Rotorua Geothermal Nuclear Sciences Ltd Field Part 3: Hydrology Confidential LIST OF APPENDICES Page APPENDIX A. DISCHARGING WELLS – CHEMICAL AND ISOTOPIC COMPOSITIONS A.0 2003 WELL RESULTS ...............................................................................................35 A.1 Summary.........................................................................................................................35 A.2 Individual Well Commentary............................................................................................35 A.2.1 Kuirau-Ohinemutu...............................................................................................35 A.2.2 Government Gardens...........................................................................................36 A.2.3 Ngapuna .............................................................................................................37 A.2.4 West Rotorua......................................................................................................37 A.3 Isotopic Analyses............................................................................................................38 A.3.1 Kuirau Park .......................................................................................................39 A.3.2 Government Gardens...........................................................................................39 A.3.3 Ngapuna .............................................................................................................39 A.3.4 West Rotorua......................................................................................................39 APPENDIX B. NATURAL FEATURES – CHEMICAL AND ISOTOPIC COMPOSITIONS B.0 2003 NATURAL FEATURE RESULTS ....................................................................53 B.1 Summary.........................................................................................................................53 B.1.1 Whakarewarewa ................................................................................................53 B.1.2 Ohinemutu - Kuirau Park.....................................................................................54