Oil demand is mostly inelastic. No matter how much or how little is produced, those who need it NEED it, so they'll compete with all others who similarly need it. The richest ones from among them get the oil first, and the poorest get nothing. The end price ends up being a function of how much oil is available versus how much the richest countries' absolutely irreducibly need for oil is versus how much wealth those countries can throw at the problem not to be left without before someone else with deeper pockets gets it.
Also, a third order effect of oil inelasticity is that if it cost too much , it decrease production and trade (might be less true now, but it was absolutely true in 2010), it lowers global demand, so the prices go down. Which is why markets can't predict oil prices, not really.
