Visualisation of Changing Reservoir Conditions at Wairakei Using a 3D Model

Abstract

This paper describes the use of the Wairakei 3D geological model to visualise changing fluid conditions within the reservoir. During 50 years of production and reinjection, the Wairakei reservoir has seen many changes. The major changes in the reservoir have been caused by pressure decline in the deep liquid zone due to fluid extraction. Where a capping formation is present, the pressure decline resulted in the formation of segregated steam zones and where the deep reservoir is connected to shallow aquifers, cooler fluids have invaded the productive reservoir. These changes have been closely monitored using physical and chemical methods. Recent development of the Wairakei 3D model has provided an opportunity to integrate some of these changes with the geological model to better understand and visualise the controls on fluid flow within the reservoir.