Origin Energy Ltd (Origin) is planning to conduct several trials into the injection of treated coal seam gas (CSG) water back into the Great Artesian Basin (GAB) for water management purposes. Origin commissioned Klohn Crippen Berger Ltd to predict the groundwater response to these injection trials. An existing regional groundwater model was provided by Origin and local mesh re-definition and boundary re-configuration was performed. This permitted a more detailed evaluation of the local effects of proposed injection activities, and allowed for representation of long term conditions. The project evaluated the potential impact on key aquifers of the GAB and on selected Town Water Supply Bores after 60 days of proposed injection at different bore sites. Two base case model conditions were considered: a ‘Best Estimate’ and ‘Max Impact’ case.
Key project tasks included:
- Modification of existing model grid and remnant boundary conditions in proximity to the injection site
- Establishment of pre-injection steady state conditions inclusive of the anticipated effects of Town Water Supply Bores in the area
- Modeling of injection for a set period of 60 days under 3 scenarios
- Particle tracking of physical injection fate and generation of head contours for key aquifers at multiple time steps, for each of the scenarios run under Best-Estimate and Max-Impact conditions