When US companies buy crude oil...do they collectively purchase it..or does each company negotiate a price?

Such as Texaco,Mobil and Exxon. Do they work together negotiating with OPEC and other countries they purchase from?When US companies buy crude oil...do they collectively purchase it..or does each company negotiate a price?
I wouldn't be surprised if US anti-trust laws prevent The Evil Oil Companies from collectively (and legally) negotiating prices from their suppliers.When US companies buy crude oil...do they collectively purchase it..or does each company negotiate a price?
They dont buy. they just take it from Iraq

biore blackheads