| Abstract |
The Rotokawa Geothermal Field has been under development since 1997 with the commissioning of the Rotokawa Power Station and the 2010 commissioning of the Nga Awa Purua Power Station. Since the field has been developed five reservoir tracer tests have been conducted. In 1998 Iodine-125 was administered to the main injection line and subsequently down three separate injection wells. In 2006 napthalene sulfonates were used for the first time on the field with four isomers injected into two wells (1,5-, 1,6-, 2,6- and 2,7-NDSA; two isomers per well). In 2009 1,5-NDSA was injected into one well following re-alignment of injection in the southern part of the field. Following the Nga Awa Purua development a tracer test was conducted in 2011 using four isomers of naphthalene sulfonates (1,5-, 1,6-, 2,6- and 2,7-NDSA) in four separate injection wells. None of these tracers were detected in the field study. Autoclave testing by Mountain and Winick (2012) found these isomers were not thermally stable and samples from the 2011 test were reanalyzed for predicted breakdown products (2-NSA and 1-NSA). 2-NSA was found in a number of samples confirming suspicions around temperature instability. In 2013 Iodine-125 was injected alongside 2-NSA into the main brine injection well in the field to benchmark 2-NSA performance. This paper will discuss each reservoir tracer test, focusing on the field configuration and findings. |