Oil prices, which were little changed in early Asian trade on Friday, were on track to end higher for a second straight week following a large cut in U.S. interest rates and declining global stockpiles.

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.

Oil futures rose Thursday, gaining ground alongside global equities and other assets perceived as risky, a day after the Federal Reserve delivered a large interest-rate cut and set the stage for further easing of monetary policy.