Most people talk about CCS as a surface problem — capture, transport, policy. In reality, most of the risk sits underground.
The issue is simple: we treat CO₂ injection like a normal reservoir operation. It isn’t.
From what I’ve seen, the biggest problem is overconfidence in the subsurface. Projects often start with limited data, then rely heavily on models that assume the reservoir will behave in a clean, predictable way. It rarely does.
Heterogeneity gets underestimated. Caprock behaviour is simplified. Pressure response is not fully understood. You run the model, get comfortable numbers, and proceed — but the field rarely matches those assumptions.
Then there’s the CO₂ itself. It’s not just another injected fluid. It changes the system.
You get interactions with rock and formation fluids — dissolution, precipitation, wettability shifts. Small effects individually, but together they can change flow paths and injectivity over time. Most models don’t capture this properly, especially over longer periods.
Injection strategy is another weak point. Too often it’s designed like waterflooding — push fluid in, manage pressure, expect predictable displacement. With CO₂, the physics are different. Density, mobility, and phase behaviour all complicate things. If you push too hard, you risk pressure buildup and integrity issues. If you’re too conservative, storage efficiency drops.
What makes it worse is that many projects only react after problems show up. Monitoring is used as a diagnostic tool instead of a control tool.
The pattern is clear:
- assumptions go in at the start
- models reinforce those assumptions
- reality challenges them later
If you want CCS to work consistently, you have to flip the approach.
Start by accepting uncertainty in the subsurface — not ignoring it. Spend more effort on reservoir characterization before injection. Treat geomechanics, flow, and chemistry as a coupled system, not separate analyses. And once injection starts, adjust continuously based on real data.
CCS is not a “set and forget” operation. It’s dynamic. The subsurface evolves.
Most failures don’t come from lack of technology. They come from treating the subsurface as simpler than it actually is.
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