| Title | Injection Management in Kawerau Geothermal Field, New Zealand |
|---|---|
| Authors | Mohsen ASKARI, Lutfhie AZWAR, John CLARK, Charis WONG |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Geothermal, Injection, Strategy, Kawerau, New Zealand |
| Abstract | An adaptive management and injection strategy has been used to ensure that the Kawerau power plant has injection capacity to run at full load and balance pressure support to the field while preventing thermal breakthrough to production areas. A key part of this strategy is understanding injection well interaction. A strategy was developed with active reservoir testing and analyses used to maintain injection capacity. Injection well capacity was initially measured through standard multi-rate completion tests following drilling. Subsequent monitoring was performed by continuous monitoring of wellhead pressure and injection rate; where no positive wellhead pressure was observed, downhole pressure monitoring tubing (i.e. capillary tubing) was installed to provide a fluid level monitor injectivity increase or decline. Wellbore models were used to estimate the full injectivity curve and its change over time. Tracers and chemical signatures were used to understand injection return to producers. Various injection well characteristics have been observed over more than five years of operation. Even though the deep injection wells are drilled within a 4km2 area, behaviors range from steady performance (no stimulation or capacity degradation) to signs of well interference and mineral deposition. Integration of information gathered from injection performance monitoring has resulted in better understanding of injection fluid flow-paths, forecasting of long-term injection capacity, management of chemical dosing of injection fluid and better planning for make-up injection well locations. |