Regional-scale advective, diffusive, and eruptive dynamics of CO₂ and brine leakage through faults and wellbores

Regional-scale advective, diffusive, and eruptive transport dynamics of CO₂ and brine within a natural analogue in the northern Paradox Basin, Utah, were explored by integrating numerical simulations with soil CO₂ flux measurements. Deeply sourced CO₂ migrates through steeply dipping fault zones to the shallow aquifers predominantly as an aqueous phase. Dense CO₂-rich brine mixes with regional groundwater, enhancing CO₂ dissolution. Linear stability analysis reveals that CO₂ could be dissolved completely within only ~500 years. Assigning lower permeability to the fault zones induces fault-parallel movement, feeds up-gradient aquifers with more CO₂, and impedes down-gradient fluid flow, developing anticlinal CO₂ traps at shallow depths (<300 m). The regional fault permeability that best reproduces field spatial CO₂ flux variation is estimated 1 × 10^-17 ≤ k_h < 1 × 10^-16 m² and 5 × 10^-16 ≤ k_v < 1 × 10^-15 m². The anticlinal trap serves as an essential fluid source for eruption at Crystal Geyser. Geyser-like discharge sensitively responds to varying well permeability, radius, and CO₂ recharge rate.