corrosive species and scaling in wells at olkaria ... - Orkustofnun

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0,3 13 Weeks (06-07-2006 to 14-10-2005) 0,25 Thickness (mm) 0,2 0,15 0,1 0,05 A 0 Well NJ- 14,coupon # 10 Well NJ-22, coupon # 25 After heat exchangers, coupon # 16 At retention tank, coupon # 17 At injection well, coupon # 20 thickness (mm) B 0,35 0,3 0,25 0,2 0,15 0,1 0,05 0 29 Weeks (06-07-2005 to 30-01-2006) At retention tank, coupon # 18 At injection well, coupon # 19 FIGURE 38: Scale thickness at the various test sites for, a) 13 weeks test, and b) 29 weeks test 40
8. EVALUATION OF SCALES DEPOSITED AT OLKARIA WELL OW-34, KENYA Olkaria well OW-34 was drilled as a make up well together with wells OW-33, OW-32, OW-31, OW30 and OW-29 after steam decline was experienced in the Olkaria East Production Field during the first five years of production. Well OW-34 was connected to the steam gathering system in March, 2001 and was disconnected in September, 2002 after its output, as measured by the pressure drop across the orifice plate, indicated a substantial drop. On dismantling the flow pipes and wellhead equipment, a thick deposit of scale which was intense, almost 1 inch thick, was found inside the two phase pipe line. The scale also formed in the wellhead separator and in the separated water flowline. Since the commissioning of the Olkaria I plant and production from the Olkaria East Production Field, until 2002 no other well had experienced this kind of intense scale deposition. Well OW-34 is anomalous. The concentration of chloride in the water is high because of its discharge enthalpy. This was unusual and what caused the scale to form was not known. The general location of wells in Olkaria East Production Field with well OW-34 is shown in Figure 39. 8.1 Output characteristics of well OW-34 Three flow tests have been conducted on this well, in 1993, 1996 and 2003. The first flow test was carried out upon completion of drilling, the second to monitor tracer tests and the effect of cold water injection in well OW-R3 and the third to investigate the causes of decline in steam output. The well was discharged under different throttle conditions using different “lip pressure” pipe sizes i.e. 8”, 6”, 5”, 4” and 3”. During the first test enthalpy varied between 2640 kJ/kg and 2680 kJ/kg and the water flow rate between 0.85 and 1.55 t/hr. In the second test, the discharge enthalpy was about 2650 kJ/kg and water flow rate between 2.2 and 3.3 t/hr, while in the third test enthalpy ranged from 2670 kJ/kg to 2675 kJ/kg and water flow rate from 1.5 t/hr to 2.1 t/hr. A summary of these tests is shown in Table 9a, in Appendix A (Opondo and Ofwona, 2003). FIGURE 39: Location of wells in Olkaria East production field When the well was connected to the production system, steam output well declined from ~42.8 t/h (Kariuki and Opondo 2001) in June 2001 to 7.2 t/h in March 2002. The output of well OW-34 with time when it was connected to the production system is shown in Table 9 b, in Appendix A. While the enthalpy differences may appear small, at such high enthalpies close to the enthalpy of dry steam these small differences have tremendous effects on the solute content of the water discharged at atmospheric pressure. Over all the discharge tests, the discharge enthalpy varied between 2640 kJ/kg and 2680 kJ/kg at the throttle conditions and the steam fractions calculated at atmospheric pressure (X s ) are high, or between 0.9973 and 0.9996. 41
Page 1 and 2: GEOTHERMAL TRAINING PROGRAMME Repor
Page 3 and 4: INTRODUCTION The Geothermal Trainin
Page 5 and 6: ABSTRACT The Olkaria geothermal sys
Page 7 and 8: Page 9. CONCLUSIONS ...............
Page 9 and 10: 1. INTRODUCTION For many countries
Page 11 and 12: deposition does not occur at depth
Page 13 and 14: The rate of sulphide precipitation
Page 15 and 16: the Western Sectors. The Olkaria II
Page 17 and 18: 46.4 MWe and 125 MWt. A shallow ste
Page 19 and 20: 3. SAMPLING AND ANALYSIS 3.1 Sample
Page 21 and 22: 4. FLUID COMPOSITIONS The compositi
Page 23 and 24: 5. CALCULATION OF AQUIFER FLUID COM
Page 25 and 26: increases the difference in tNaK -
Page 27 and 28: The procedure for calculating aquif
Page 29 and 30: Concentrations of CO 2 at equilibri
Page 31 and 32: High concentrations of HCl can be g
Page 33 and 34: variation in chloride concentration
Page 35 and 36: A 240°C a steam cap overlies the l
Page 37 and 38: The solubility of CO 2 in water cha
Page 39 and 40: where it passes through mist elimin
Page 41 and 42: Coupon holder loosened the screws a
Page 43 and 44: Coupon # 20 (Re-injection well): A
Page 45 and 46: 1900 1800 C #10 Well NJ-14 1700 160
Page 47: 0,3 13 Weeks (06-07-2005 to 14-10-2
Page 51 and 52: atmospheric pressure. The results d
Page 53 and 54: The IR spectra of scale samples #1
Page 55 and 56: 9. CONCLUSIONS Olkaria well fluids
Page 57 and 58: REFERENCES Allegrini, G., and Benve
Page 59 and 60: D’Amore, F., Truesdell, A.H., and
Page 61 and 62: Hurtado, R., Andritsos, N., Mouza,
Page 63 and 64: Saemundsson, K., and Fridleifsson,
Page 65: APPENDIX A: Tables with analyses, c
Page 74: APPENDIX C: Analyses of scales and
Page 80 and 81: Spectra for scales from coupon # 16
Page 82 and 83: Spectra for Olkaria OW-34 scale # 1

corrosive species and scaling in wells at olkaria ... - Orkustofnun

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