This appears to be pure speculation, I've not found this figure anywhere else. It was not a production well and shouldn't the BOP have shut automatically ?
I think I read something about them cementing in around the casing as they were done with the hole (to it’s final depth, exploration hole). In the environmental field they fill them with grout with some cement at the top. Not sure how they close off a deep oil/gas well though. But, if they were doing something similar, they might have deactivated or removed the BOP?
I think it is just a bad coincedence that it happened on “Earth Day”. But, no doubt it will be used in the war against free markets. (Oh, I meant “global warming”).
Crude oil always measured in barrels until some AP hack needs to make it sound worse than it is.
I'm surprised they didn't go metric and announce that it was over a million liters per day.