UT Austin study: corner pore volume key to CO2 plume accuracy

Accurate prediction of bottom-hole pressure (BHP) and CO2 plume migration is vital for safe geological carbon storage, but real-world simulations often use truncated domains that introduce artificial boundary effects. In a new arXiv preprint, Romal Ramadhan and colleagues from the University of Texas at Austin systematically compared ten reduced-domain boundary treatments against full-domain reference simulations in homogeneous and heterogeneous reservoirs. They tested uniform pore-volume multipliers, transmissibility modifiers, corner-adjusted pore-volume corrections, layered corrections, and gradual modifiers, using BHP RMSE, NRMSE, peak pressure deviation, and plume Intersection over Union (IoU) as metrics. Their results show that preserving corner pore volume is the single most important factor for accurate truncated-domain modeling. Uniform treatments that neglected corner storage produced large pressure errors (BHP RMSE 362–382 psi in homogeneous models, 250–304 psi in heterogeneous models) and plume IoU values near 0.80–0.84, meaning roughly 16–20% of the combined plume area was misrepresented.

Corner-adjusted scenarios substantially reduced pressure errors and raised plume IoU above 0.94 in both reservoir types. However, transmissibility correction—while beneficial in homogeneous reservoirs—could over-restrict flow across variable-permeability boundaries in heterogeneous cases, increasing BHP error and contracting the predicted plume. The authors found that the gradual modifier combined with transmissibility correction delivered the most consistent performance across both reservoir types, achieving BHP NRMSE below 3.7% and plume IoU above 0.97. These findings provide practical guidance for practitioners running CO2 storage simulations on truncated grids, enabling more reliable pressure and plume predictions without requiring full-domain computational expense.