I think you mean Crateria. The maps here are wrong. The instruction booklet shows that the blue area is Crateria. Many consider Super Metroid's map to have retconned this fact, but whatever. It was listed as such back then.
Anyway, the area that I've found to be the fastest is in Brinstar directly right of entering it. That tunnel that connects Crateria (blue area) to Brinstar (orange area), well just keep going right from there. It's where you have to go to get Bombs and one of the Ice Beams. Well the enemies that float around moving up and down, back and forth in seemingly random fashion, the Wavers, yeah they typically net you 20 energy each. I just Screw Attack through those going back and forth through this corridor. Don't take to long to fill all 6 tanks that way. --- Freelance Quality Assurance, L.A. | Current contract: Electronic Arts. Rockman Zero Collection: http://www.capcom.co.jp/rockman/zero/index.html