From the moment they get yanked out of the ground to the moment they go into your fuel tank or home furnace, oil and gas have a long and complex journey to make. While some companies both extract the stuff and ship it, the job of transporting and storing petroleum -- along with its various refined versions and by-products -- usually falls to pipeline and terminal operators like Buckeye Partners (NYSE: BPL) and NuStar Energy (NYSE: NS).As master limited partnerships (MLPs), the rules for Buckeye and NuStar are a bit different than for ordinary stocks.