3D Geological Modelling Using New Leapfrog Geothermal Software

Abstract

Leapfrog Geothermal is an innovative 3-D modelling visualisation software and resource management tool, developed by ARANZ Geo (Applied Research Associates Ltd), with geoscientific input from GNS Science, to meet the 3-D computing needs of the geothermal industry. Leapfrog Geothermal is based on implicit modelling methods that represent geology, structure, geophysical and reservoir data with fitted mathematical functions. Complex geological models are built by combining measured field data, specialist interpretation and user editing. The advantage over conventional grid based systems is one of flexibility and speed, with a model that can be used to populate grids with a range of parameters, depending on user purpose.

Hydrothermal alteration, geophysical data, temperature and other reservoir data are modelled as transition surfaces and/or numerical models, and can be combined with rock property and well feed zone data to refine the hydrological structure of a geothermal system. Downhole logging data (e.g. BHTV images) can be integrated to help define fault geometries, lithological discontinuities, and fracture network patterns. The resultant geological model consists of closed unit boundaries that help establish structural and rheological controls on fluid flow (i.e. permeability structure) in the geothermal system.

A tool for drillhole design and well targeting has recently been added to Leapfrog Geothermal. Current development focuses on integration of output data from numerical reservoir simulation (e.g. Tough2, Feflow) software at the resolution and scale required to visualise the past and predicted response of the system to development, and aid resources management. Leapfrog Geothermal is already used


by developers at geothermal fields in the Taupo Volcanic Zone (New Zealand), as it can rapidly build user-friendly models, assist drilling engineers and geoscientists in their day to day activities, and provide insights that support long-term, strategic field management decisions.