Working with Multi-million Block Geothermal Reservoir Models

Abstract

Waiwera is an open-source, parallelized geothermal reservoir flow simulator which gives the ability to reliably run and calibrate complex geothermal reservoir models made up of millions of blocks. However, running such large models brings a number of new challenges that must be addressed in order to realise the benefits of the increased computational power. This paper describes these new challenges and our teams approaches for handling them. The challenges can be broadly categorised as either model setup or model post-processing. There are a small number of issues relating to simulation control that are also discussed. For model setup, our techniques for the following are discussed: - Grid definition and generation - Distributing rock properties to the model - Representing faults and fractures - Defining wells and their feedzones - Specifying boundary conditions including deep inputs - Upscaling/downscaling between different grid resolutions For model post-processing we make extensive use of python scripting tools and graphical user interfaces such as Leapfrog. We describe our techniques for extracting information from very large transient simulation output files and then presenting results in a range of meaningful formats to provide stakeholders with tools to support their decisions. Methods for handling very large sequential simulations are also discussed. Both model setup and model post-processing are demonstrated using examples from current real-world geothermal reservoir modelling projects.