Keeping geoscientists busy

Geoscientists can go too far in the relent­less pursuit to de-risk all elements that could cause a CO₂ store to leak. At least, that is my take based on listening to a presentation by a member of the Endurance Partner­ship at the Seismic confer­ence in Aberdeen.

What happened?

North of the Endurance CO₂ store, which is going to be the first Triassic saline aquifer in the UK North Sea that will be used as a site for CO₂ injection, is another cluster of potential sites that can be used for the same purpose. Two of those potential sites were the topic of a talk delivered by Adrian Merry from TotalEnergies, one of the three sharehold­ers of the Northern Endur­ance Partnership.

One of those sites will probably lend itself for CO₂ storage, as it is a gentle an­ticlinal structure with a good seal on top. This one is marked Closure 1 in the sketch. However, the next-door anticline shows some major faults cross-cutting the crest of the structure, offsetting the reservoir. You don’t need to be an expert to see that it would be risky to store CO₂ in there. That isn’t the plan either.

Knowing that the study was done not even to de-risk leaking CO₂ but to de-risk a leaking brine, this project looks like people are desperately looking for potential problems to justify the mobilisation of kit

Yet, a seismic acquisi­tion was performed over this faulted structure in order to better assess how far the faults continued into the overburden. Why? Because there is a risk that CO₂ stored in Closure 1 would cause a pressure increase in the wider Triassic reservoir – there is a connection be­tween the two sites – which may cause formation water to reach the seafloor via the above-described faults.

Is that a bad thing? The only rationale that was brought forward was some­thing along the lines of “another composition” and “unwanted”. But is that bad? I don’t think it is necessarily so, especially because this is all happening in a shallow sea with a major tidal current.

And there is another reason why there was no need to mobilise a seismic acquisition vessel, even when knowing that the whole exercise only lasted a week. As was shown during the same talk, modelling demonstrated that the faults are likely sealing, and fur­ther geomechanical work also suggested that fault re­activation is unlikely. These studies alone should have been sufficient to not move ahead with the survey.

Overlooking all of this, and knowing that the study was done not even to de-risk leaking CO₂ but to de-risk a leaking brine, this pro­ject looks like people are desperately looking for po­tential problems to justify the mobilisation of kit and thus keep some geoscientists busy. I’d rather plan a devel­opment well.