| Title | Testing Direct Use Geothermal Wells in Rotorua, New Zealand |
|---|---|
| Authors | S. Ady Candra and Sadiq J. Zarrouk |
| Year | 2013 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Direct use wells, Rotorua, Self-discharging, Down-hole Pump, Air-lifting, Down-hole heat exchangers and Reinjection wells |
| Abstract | The township of Rotorua is located on top of a unique shallow geothermal system, which has enabled easy access to the resource and the utilization of several commercial and domestic direct use installations. However, there is no established standard methodology for the management of wells, especially in the way that they are tested and measured. Down-hole testing and flow measurement are key factors in predicting and investigating the conditions and characteristics of geothermal wells. This study collects and uses data from all types of geothermal wells in order to classify their direct use. There are several types of geothermal wells for direct use application in Rotorua, most of these wells are shallow bores less than 200 m deep with diameters of 100 mm, and 150 mm and commonly without liners. The types of direct use wells include self-discharge, down-hole pump, air-lift discharge, down-hole heat exchanger (production wells) and reinjection wells. This classification is consequently used as the basis for recommending a standard methodology for conducting well test and production measurement, with the following objectives in mind: „h Determining the location of the feed zones, the well injectivity (well take). „h Productivity of the well (production test). „h Assessment of the performance of the well over time and monitoring the condition of the borehole. „h Scaling potential in the well The data is also needed for monitoring reservoir conditions, assess the sustainability and investigating the environmental impact of exploitation of the geothermal resource for direct use of geothermal energy. New temperature contour maps for the township of Rotorua were developed based on the available down-hole temperature data. Those illustrate the hydrology condition and geothermal regions in Rotorua. It will be of use when targeting new production wells and help decide the potential type of well for a given location. |