Crude prices rallied this week on the growing anticipation that OPEC would extend its production reduction agreement through the end of 2018. That should help drain off more of the market’s excess inventory, which should at least put a floor under oil prices. For the week, the U.S. oil benchmark, WTI, rose about 3% to more than $53 a barrel, finishing at the highest level in six months, while the global oil benchmark, Brent, increased nearly 4% and topped $60 a barrel for the first time in more than two years.