This comes on the heels of a deadly weekend attack by Islamic militants in the oil-producing city of Khobar.
Opec is meeting Thursday and may agree to boost production to calm the markets.
Some analysts say it hasn't reached a crisis point yet.
"The oil market, as some people say, has been spooked lately because of these attacks. But it will take something much bigger, sadly, in some respects to affect very badly the oil market," said Dr. Leo Drollas of the Center for Global Energy Studies.
Saudi Arabia has said it would increase production and help lower crude oil prices, which have been at record highs. Much will depend on the Opec meeting this week.