Holding far above $60 may prove challenging for another reason: it’s come to be seen as the upper end of a price range that’s supported by OPEC. While the producer group itself denies any such a range exists, it is unlikely members would fully comply with cuts if prices rose that high, Petromatrix GmbH Managing Director Olivier Jakob wrote in an emailed report.

https://www.bloomberg.com/news/articles/2017-09-26/oil-rally-has-bulls-on-top-but-60-plus-seen-as-hard-to-sustain