CO₂ seal check
Does the caprock hold, and for how long? Runs from your saved storage site plan — none saved yet, so this shows the plan page's starting values, not a real site. Enter your site there and this page follows.
Whole field, through injection and shut-in
Solid line: pressure on the seal (buoyancy + injection) at the most-loaded well. Red dashes: seal entry pressure. Grey line: shut-in. Dashed line: how far CO₂ has pushed into the seal (top = all the way through). Time axis is logarithmic. Holding the peak pressure forever would cross in about 195 years — the real pressure falls after shut-in, which is why this answer differs.
Pressure adds up Theis (1935) from every well on the project layout, with shut-in. CO₂ only advances into the seal while pressure is above entry; it is held where it stopped (not pushed back), which leans cautious. Uniform rock, no relative permeability.
Entry pressure exceeded by 219 psi during injection. If that pressure were held, CO₂ could cross the 200-ft seal in about 916 years.
Dissolved CO₂ diffusing through the seal takes about 588,784 years to cross it, whether or not the seal holds.
Buoyancy vs entry pressure per Watts (1987); injection pressure from Theis (1935) as on the site plan (one neighbour only — see the whole-field section above for every well and shut-in). Breach time integrates Darcy flow across the seal at constant excess pressure, t = φ·μ·L²/(2·k·Δp), with CO₂ viscosity 0.046 cp (Fenghour et al. 1998) — no relative permeability, so a fast-breach bound; injection pressure falls after shut-in, so real breach is slower. Diffusion time is L²/D. Seal porosity and diffusion are assumptions.
How injection pressure changes the crossing time
Same seal, buoyancy and CO₂ viscosity; only the injection pressure on the seal changes. The row marked “this site” is the run above.
| Injection pressure | Total on seal | vs entry | Crossing time |
|---|---|---|---|
| 0 psi | 19 psi | 81 under | Seal holds |
| 75 psi | 94 psi | 6 under | Seal holds |
| 81 psi | 100 psi | +0 over | 461,005 years |
| 150 psi | 169 psi | +69 over | 2,894 years |
| 225 psi | 244 psi | +144 over | 1,391 years |
| 300 psi (this site) | 319 psi | +219 over | 916 years |
| 450 psi | 469 psi | +369 over | 544 years |
| 600 psi | 619 psi | +519 over | 387 years |
| 900 psi | 919 psi | +819 over | 245 years |
Crossing time scales as 1 ÷ (pressure over entry): halving the excess doubles the time. Below 81 psi of injection pressure the seal holds against CO₂ flow; diffusion still applies.