Australia FEFLOW Regional groundwater Geomechanical effects, and dual porosity nature of coal Deterministic uncertainty Australia Pacific LNG all assumed insignificant analysis only: Sensitivity Pacific LNG (172,740 km2 model Project, analysis (two extreme (2010), domain) Simple (non-coupled) approach to groundwater–surface Australia cases only) for aquifer, Geoscience water interaction adopted Finite element method recharge and stream Australia and (FEFLOW) allows Coal horizontal anisotropy not modelled conductance Habermehl improved definition of parameters. Effect of (2010) Coal not modelled independently of coal measures complex geology sensitivity-adopted CSG well represented by constant pressure head parameter values on Dual-phase flow implicitly (rather than pumping flow rates) calibration performance accounted for by reducing Hydraulic connectivity of geologic structural features discussed coal seam permeability ignored Indicated significance of Cumulative impacts Discussion of hydraulic fracturing severely limited assessed (including other hydraulic parameters and range of drawdown CSG developments) Hydraulic parameters assumed for most model layers magnitudes due to limited data Simplified hydrogeological model, which may only reflect a partial understanding of the Surat Basin Connectivity between aquifers uncertain as geological structure poorly understood Upward propagation of depressurisation from coal deposits in the Basin not included
Australia Pacific LNG Project, Australia FEFLOW Regional groundwater (172,740 km2 model domain) Finite element method (FEFLOW) allows improved definition of complex geology Dual-phase flow implicitly accounted for by reducing coal seam permeability Cumulative impacts assessed (including other CSG developments) Geomechanical effects, and dual porosity nature of coal all assumed insignificant Simple (non-coupled) approach to groundwater–surface water interaction adopted Coal horizontal anisotropy not modelled Coal not modelled independently of coal measures CSG well represented by constant pressure head (rather than pumping flow rates) Hydraulic connectivity of geologic structural features ignored Discussion of hydraulic fracturing severely limited Hydraulic parameters assumed for most model layers due to limited data Simplified hydrogeological model, which may only reflect a partial understanding of the Surat Basin Connectivity between aquifers uncertain as geological structure poorly understood Upward propagation of depressurisation from coal deposits in the Basin not included Deterministic uncertainty analysis only: Sensitivity analysis (two extreme cases only) for aquifer, recharge and stream conductance parameters. Effect of sensitivity-adopted parameter values on calibration performance discussed Indicated significance of hydraulic parameters and range of drawdown magnitudes Australia Pacific LNG (2010), Geoscience Australia and Habermehl (2010)
csg-modelling-groundwater-impacts.docx