Casing is not I repeat not drill pipe. Drill pipe has a much thicker wall than casing. Casing is used when cementing abd plugging. This is where an inherent gap in the process is acknowleged. It was during period that that methane gas bubble breached. The BOP would not have helped in any case.
I have seen how thick some of the drill pipe is.
In any event terrible situation going on out there