Multiscale static and dynamic modelling of Precipice Facies, Wendoan, Surat Basin, Queensland

ANU-FEI-ANLEC Project: Multiscale static and dynamic modelling of Precipice Facies, Wendoan, Surat Basin, Queensland

Subproject 3b: Develop unsteady state upscaling solvers that honour geological heterogeneities and the physics of flow at different scales

Project focuses on the impact of small-scale heterogeneity of fluviatile sandstones on the migration of CO2 in the sub-surface formations that shall be used by Australian flagship CO2-geo-sequestration projects. The project is aimed at the identification and computational application of flow-regime-aware saturation functions (constitutive relationships) that will be constrained by a combination of high-resolution X-ray scanning, core-flooding experiments and high-performance multi-scale pore-network and continuum scale numeric simulation. The results will inform injection simulations at the Wendoan flagship site in the Surat Basin, Queensland.

In particular, we are implementing a new unsteady state solver for the computation of equivalent relative permeabilities, in the presence of combined gravitational, capillary and viscous forces (hybrid FEM-FVM pressure-saturation formulation including capillary pressure in global pressure equation). The idea is to make a catalogue of possible flow regimes (force balances) and automatically select the most efficient and relevant solver accordingly, to be used for the flow-dependent property upscaling. The impact of flow-regime aware saturation functions on the CO2 plume spreading will be demonstrated using heuristic models incorporating realistic bedding structures at the near wellbore and single geo-cell scale.

Near wellbore geological model, created with SBED software (~400,000 cells); two stacks of dipping parallel laminae form the bottom of the model while different forms of cross-bedding structures constitute its upper part; model dimensions are 50 cm x 50 cm x 25 cm.

Micro-CT images and this continuum scale models of cm-scale heterogeneity will serve as an input to the relative permeability computations (courtesy of C. Milliotte, FEI).