A 3-D Representation of the Wairakei Geothermal System (New Zealand) using "Earth Research" Geothermal Visualisation and Modelling Software

Abstract

New visualisation and modelling software, “Earth Research”, has been used to develop a 3-D image of the geology of the Wairakei geothermal system (New Zealand). Earth Research was developed specifically for the geothermal industry, and provides a major advance on traditional 2-D representations of field stratigraphy, structure and hydrothermal alteration, with work well advanced to include a TOUGH2 numerical reservoir simulation capability. Stratigraphic contact surfaces and hydrothermal alteration are modelled using implicit functions based on drillhole data, with user-defined variograms, anisotropy and resolution. Structural features are incorporated by the generation of planes that subdivide the interpolation space into individual domains. The 3-D representation of the Wairakei geothermal system includes stratigraphy and hydrothermal alteration, inferred faults and reservoir parameters, and provides insights into geological controls on fluid flow, basement and volcanic morphology, and aids correlation of stratigraphic units. The Wairakei 3-D model is a powerful tool used by Contact Energy and GNS Science for designing drilling strategies, and refining the geological framework of the system. The processing speed and data capacity of implicit modelling means the Earth Research 3-D geology model can be used to represent new information in near-real time – with immediate value to a developer during well drilling operations and for resource management.