Bignall, G.; Milicich, S.D. 2012 Kawerau Geothermal Field : geological framework. Lower Hutt, N.Z.: GNS Science. GNS Science report 2012/33 28 p.
Abstract: This report details the geology of the Kawerau Geothermal Field. The report provides geological information in support of a 2011 resource consent application for the take and injection of 45,000 tonnes per day of geothermal fluid from the Kawerau geothermal system by Ngati Tuwharetoa Geothermal Assets (NTGA). At present, fluid extracted from existing resource consent holders (i.e., Mighty River Power Ltd., NTGA, and Geothermal Development Ltd.) totals an annual daily average of 94,000 tonnes, with a maximum daily extraction rate of 113,560 tonnes. A good understanding of the stratigraphy and structure of the Kawerau Geothermal Field, as well as controls on permeability and hydrothermal alteration assist in development of the conceptual model of the system. Geological data for the Kawerau Geothermal Field has increased over the last 30 years, with the understanding of the field stratigraphy and structure much clearer than when geothermal drilling began in the early 1950s. The Department of Scientific and Industrial Research and the Ministry of Works carried out initial scientific surveys and shallow drilling in 1951/52 to investigate the geothermal potential of the area for power production and process heating. Since that time, more than 60 geothermal wells have been drilled in the Kawerau area. (auth)