The following is an excerpted version of the article at Crude Oil Peak
BP annually publishes a review with so-called proved oil reserves. The latest version is from June 2016. It is well known that the reserve definitions used in this review are inconsistent. We look at the anomalies in the reserve history. (Fig 1) Following volumes have been added over the years: 300 Gb of resources by OPEC in the 1980s, 200 Gb from tar sands in the late 1990s and early 2000s and another 200 Gb of heavy and extra heavy oil from Venezuela from 2007 onwards. Tar sands and heavy oil have a completely different production profile from conventional oil.