Minimum 'block' fuel? The minimum fuel required for takeoff?
Your question about the minimum fuel doesn't make sense. If the low fuel lights come on you don't necessarily flame out in the event of a g/a. You have x amount of fuel(time) left. If you exceed x time you'll flame out. If you land inside of x minutes you won't flame out.
And fuel burn varies greatly between fully configured, partially configured, or clean. The time spent in any of the configurations changes the amount of time to flameout.