The Brent/WTI spread has historically ranged between $4/bbl and $8/bbl, but it can expand or contract based on factors related to U.S. and international supply and demand conditions. For example, the Brent/WTI spread hit nearly $14/bbl in April 2011 when protests sparked market fears of significant oil supply disruptions in the Middle East.

The surge in U.S. crude oil exports has made WTI Midland a more influential benchmark in the global oil market, leading to increased trading activity in Houston.

Oil prices fell more than 3% on Thursday on a Financial Times report that Saudi Arabia, the world's top crude exporter, will give up its $100 price target in preparation for raising output, along with OPEC members and allies in December.