| Title | RESERVOIR TRACER TEST AT THE NGATAMARIKI GEOTHERMAL FIELD |
|---|---|
| Authors | E. Buscarlet, H. Moon, I. Wallis and J. Quinao |
| Year | 2015 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Ngatamariki, Reservoir Tracer Test, Moment Analysis, Dispersion, Sorption, Modelling, Tough2 |
| Abstract | A reservoir tracer test was conducted at the Ngatamariki Geothermal Field following the commissioning of an 82 MW binary plant in October 2013. The objectives of the test were to assess the fluid flow pathways and potential connections between the injection and production wells. The geothermal fluid is produced from three deep wells in the centre of the field and is entirely re-injected back into four deep injection wells which are split between the northern and southern sectors of the field. In January 2014, four (4) types of Naphtalene Disulfonate tracers (1,5-NDS, 1,6-NDS, 2,6-NDS and 2,7-NDS) were introduced into the injection wells, and sampling of fluids from the production wells were carried out over a period of eighteen (18) months. Tracer returns were observed in the production wells, but with diverse responses: fast returns were observed in the south of the field (tracer breakthrough in 28 days) while returns from the northern injectors are slower (tracer breakthrough in 100 days at the earliest). The amount of tracers recovered ranged from 0.5 to 5%. Moment analysis of the tracers recovery curves, coupled with geologic context and process modelling using Tough2, have provided valuable information about the permeability pathways at Ngatamariki. The results highlight the permeability characteristics and structural features in the southern part of the resource, which correlates well with the data from the micro-seismic monitoring. |