December 2016 crude oil contracts opened at $50.66 on Friday on CME Globex, with morning trades between $50.33 and $50.94. January 2017 contracts opened at $51.17, trading between $51.49 and $50.84.

A drop in U.S. production and optimism that OPEC production cuts would hold helped propped up prices early in the week. Oil futures closed lower on Thursday as investors took profits.

OPEC's September agreement to cut production was heralded in some quarters as a proactive response to the global oil glut that has driven down prices for two years. But the agreement was not binding and there are no firm benchmarks specifying how much each country will have to cut. OPEC is expected to revisit the issue at a November 30 meeting in Vienna, when the issue of national quotas will be addressed.

In a research note this week, Commerzbank identified a spike in net long positions in oil futures contracts as a harbinger for an oil price rise. That, Commerzbank noted, depends "primarily on whether OPEC maintains the credibility" of its production cuts.

But the national fault lines have appeared. Ali Kardor, managing director of National Iranian Oil Company said on Monday that Iran would not honor OPEC's September agreement to cut production--Iran is exempt from the OPEC production cut agreement. Since the meeting, Nigeria and Libya have also increased production and Iran has joined Iraq and Venezuela in questioning the way OPEC calculates output in a given country.

Last week Russian President Vladimir Putin said he was ready to join with OPEC on cuts, but on October 11 Igor Sechin, head of Rosneft, the state-owned company that produces 40% of Russia's output, told Reuters that they would not honor the production cap unless there was a price freeze, not a production cut. Some observers think Russia will increase production by roughly 1.6% in 2017 to exploit the cheap ruble and lower Russian production costs.

In an event that was both extraneous and closely related, Saudi Arabia, OPEC's biggest crude oil producer, sold $17.5 billion in sovereign bonds in what has been described as an effort by the Kingdom to wean itself away from a dependence on oil revenue that dates to the last century. U.S. and Asian investors were the main buyers in a private placement deal. The $6.5 billion, 30-year portion of the deal will pay 2.1% above the yield for a comparable U.S. Treasury, or about 4.6%.