So if you stop the flow, (which was the intent) and the pressure builds up, (which everyone knows it will), and the casing fails, which could happen, it would cause trouble in the relief well?? Just don’t see it.
The risk is low, but possible. The scenario would be the well is capped and the pressure builds. That pressure will do one of a couple of things.
One it could build to an equilibrium point and the deposit becomes static - everything holds together and just reaches a steady state. This is the best outcome because then the relief well restarts drilling and intercepts at the planned point.
Another option is the pressure builds and while building there is a weak point in the existing effecting the original well bore that causes a displacement event. That displacement event either moves or rupture the original well bore. If the relief bore is to close it could be damaged in this scenario which means we start over with a relief well and in the mean time bring in the well bore from DDII. Not a good scenario.
The scenario is not likely, but then again in March I would have told you a failure of this magnitude was unlikely as well.