Once in a while an oil spokesman will let a number slip out into public and then we have to try to guess what went into the number. If Prudhoe oil costs $40 a barrel they might be adding in new exploration costs, new wells. They have some severe constraints for putting down a new drill pad, for example.
Thats definitly true. ExxonMobil however has spent billions buying back their own stock instead of putting all this windfall cash into exploration or infrastructure.