Oil futures were higher Tuesday, led by U.S. demand and underpinned by a tense geopolitical matrix. U.S. demand for crude-based products is high as Americans enjoy the summer holiday period, also known as driving season. Crude oil processing by U.S. refineries is also extremely high at this time of year, wrote Commerzbank, “and is in fact at a record level at present, which should cause U.S. crude oil stocks to decline further.”

Many investors will also be taking note that crude-oil contracts on both sides of the Atlantic have formed different structures–which means that some traditional trades are less profitable but which opens up other opportunities.

For the first time in six years, U.S. crude is $2 more expensive to buy today than it will be tomorrow. Commerzbank said in a note to clients that this “unusually pronounced” situation is “due to robust demand for immediately available crude oil in the US.”

WTI August crude on the Nymex exchange was up 0.7% at $105.25 a barrel, while the September contract is trading at $103.23 a barrel.

The August contract ends today, meaning that the price difference will be corrected, but it indicates that there is little fat in the U.S. system.

The divergent prices between the two months also offers a profit opportunity: investors who hold the contract at the time of expiration call allow it to roll over to the next month. This means, effectively, that they sell at the August price and buy in again at the September price, which translates into a $2 profit on every barrel held.

Brent, which has spent several years mainly in backwardation–leading to easy profits for investors–is now in the opposite state, known as contango. But Brent futures are more expensive further out along the curve, indicating that the market expects prices to rise.

Brent September futures were up 0.5% at $108.18 a barrel, while the October contract traded at $108.55 a barrel.

Brent prices fell for eight days to July 9, but since then the picture has been more mixed.

“There have been no signs of any easing in tensions since, rather they have intensified,” noted Tamas Varga of brokerage PVM. He listed Iran, Iraq, Syria, Libya, Israel and Ukraine as continuing hotspots