Irrationality, page-20

It’s actually kind of the opposite. Each additional barrel is worth $0 but production would sort of halt at that point, creating a price floor. Excess supply doesn’t mean unlimited supply, so there will always be value as a producer can’t continue pumping if there’s nowhere to put it. So in essence supply is always finite, equal to maximum storage capacity.

I would assume that floor is at WTI $15ish. Maybe it would dip to $10 but that would be extremely short lived. Eventually price gets so low that the market has to price in immediate action as it’s just not sustainable for even the lowest cost producers.