I believe what op meant was buying physically barrels of oil and keep them in his garage and then sell them to some manufacturer once the price goes up.
He wasnt really asking how to take advantage of that from a financial point but more of a microeconomical one.
Cola I cant really answer in a doubtless way but what you should need to consider are the costs to get in from the soil (unless you have drills in the mid east), the costs to trasport it to your location and the costs to store it in a place of your property.
Even if you were able to buy barrels at the local market and have them delivered to your garden it will still be very expensive since unlike oil companies you do not have the logistics nor the infrastructures to do so, also you surely dont have lobbists working for you at the gov so you would be paying a **** load of taxes.
I dont know also if there are laws that require a special authorization to deal in that business.
So to answer your question I would say: 1 infrastructures, 2 logistics, 3 taxes, 4 bureaucracy.
Anyway interesting question, lets see if someone can provide a more precise answer.