You're not too bright, are ya' skippy?
Oil is a GLOBAL product.
Everyone everywhere, wants oil.
When Demand is high, but supply is low, the price will increase as there are certain persons paying MORE for the share of Oil they want to Buy.
This is called Supply Economics.
And yes, speculation in one nations markets, affects other nations markets, and because of the Global Economy and it's interaction with fungible commodities like Oil, speculation of supply/demand does in fact affect the global price.
There must also be consideration of cost of the infrastructure to produce and transport the Oil, as such that current Rental/Lease rates for a Panamac-TH tanker are about $3000.00 an Hour. And it takes WEEKS for a tanker to move across the oceans. I don't even know current lease rates for drilling derricks or offshore rigs, but I would speculate millions of dollars a day.
Let me refine this by using my favourite analogy of Sierra-Leone; There a gallon of petrol costs about $25.oo.(a fortune by Sierra-Leone standards) Why? Because its a war zone, a nation basically demolished by sectarian infighting. Now with that, there is a lack of ability to bring in more Oil, this is the supply, and yet there is still a demand for oil by the people. As such, the price has risen to match the ability of supply to the demands of the people.
Oh, and about 2/3-3/4 of the worlds population uses Oil for something, whether clothes, lubrication, heat or transport.
Also, it should be considered that about 85% of USA daily demand is imported from Canada and Mexico, both of whom are using slant/drilling technology to pump out the oil that is situated under USA soil. I was even surprised to learn CHINA is building Oil Rigs offshore of Cuba, midway to Florida.
I will end stating: Damn The USA has been stupid in denying itself its own natural energy resources, in deference to scenery and political bickering.