Surat Basin (QGC, MODFLOW Regional groundwater model Dual-phase flow, coal dual porosity and anisotropy, and None – 2009) coal seam gas region divided into geomechanical effects not included three subdomains (hydraulic Coal seams not modelled independently of coal measures compartmentalisation assumed) No consideration of rainfall recharge Time-varying constant head Simplified geology, homogeneous isotropic conditions boundary condition used to Cumulative impacts not assessed represent well field (rather than Apparently no accounting of groundwater–surface water pumping/flow rates) interaction Queensland Water MODFLOW Regional groundwater model Modelling of historical coal seam gas operation, included Uncertainty analysis was carried out Resources (CWC, simulation of multiple coal seam gas operations, was used to using multiple simulations incorporating (300,000 km2 model domain) 2012) develop and assess cumulative impacts and aggregate changes to the model. The results of this groundwater extraction associated with coal seam gas analysis were used to assess uncertainty extraction in the predicted impacts Namoi Catchment Regional groundwater model Separate model of surface water system Sensitivity analyses carried out to assess (Schlumberger (30,000 km2 model domain) uncertainty associated with rock Multi-layered model to address future coal seam gas and coal Water Services, permeability and recharge values coal seam gas well fields modelled mine development. Modelling of existing, planned and 2012) adopted possible development using a specified extraction rate Cumulative effects assessed through multiple model over each well field modelled analyses by comparing the results for a range of alternate Cumulative impacts assessed development scenarios with a base case of limited (existing and proposed development developments) Groundwater impacts on surface water obtained using nominated head boundaries to represent permanent Water courses Powder River MODFLOW Regional groundwater model Dual-phase flow, coal dual porosity and anisotropy not None Basin, Montana, included. (1240 km2 model domain) US (Myers, 2009) Geomechanical effects assumed to have no impact Subregional constant head boundary condition used to Coal seams not modelled independently of coal measures represent coal seam gas well field Cumulative impacts not assessed Implicit (uncoupled) groundwater–surface water interaction
Surat Basin (QGC, 2009) MODFLOW Regional groundwater model – coal seam gas region divided into three subdomains (hydraulic compartmentalisation assumed) Time-varying constant head boundary condition used to represent well field (rather than pumping/flow rates) Dual-phase flow, coal dual porosity and anisotropy, and geomechanical effects not included Coal seams not modelled independently of coal measures No consideration of rainfall recharge Simplified geology, homogeneous isotropic conditions Cumulative impacts not assessed Apparently no accounting of groundwater–surface water interaction None Queensland Water Resources (CWC, 2012) MODFLOW Regional groundwater model (300,000 km2 model domain) Modelling of historical coal seam gas operation, included simulation of multiple coal seam gas operations, was used to develop and assess cumulative impacts and aggregate groundwater extraction associated with coal seam gas extraction Uncertainty analysis was carried out using multiple simulations incorporating changes to the model. The results of this analysis were used to assess uncertainty in the predicted impacts Namoi Catchment (Schlumberger Water Services, 2012) Regional groundwater model (30,000 km2 model domain) coal seam gas well fields modelled using a specified extraction rate over each well field modelled Cumulative impacts assessed (existing and proposed developments) Separate model of surface water system Multi-layered model to address future coal seam gas and coal mine development. Modelling of existing, planned and possible development Cumulative effects assessed through multiple model analyses by comparing the results for a range of alternate development scenarios with a base case of limited development Groundwater impacts on surface water obtained using nominated head boundaries to represent permanent Water courses Sensitivity analyses carried out to assess uncertainty associated with rock permeability and recharge values adopted Powder River Basin, Montana, US (Myers, 2009) MODFLOW Regional groundwater model (1240 km2 model domain) Subregional constant head boundary condition used to represent coal seam gas well field Dual-phase flow, coal dual porosity and anisotropy not included. Geomechanical effects assumed to have no impact Coal seams not modelled independently of coal measures Cumulative impacts not assessed Implicit (uncoupled) groundwater–surface water interaction None
G2-Gippsland-impact-assessment-report-June-2015.docx