This, the Norway-headquartered consultancy points out, is a different figure to BP's latest statistical review released this week.
"In order to reach a reserves estimate as high as the 1730 billion barrels noted in BP's calculation, Rystad Energy's database would need to include 500 billion barrels from its estimates of yet undiscovered oil," it said.
Breaking it down it says the Permian holds 100Bbbl, though shale and tight resources have remained flat last year production was largely replaced by improvements in well configuration, driven by supermajors expanding their footprint in the area and then fine tuning operations.
"We also note that production has not been fully replaced by increased reserves in some US shale plays, including Eagle Ford in Texas and Utica in Ohio," CEO Jarand Rystad said.
"Oil companies have been focusing on core development and cash flows rather than exploration and de-risking non-core assets."
Further afield one of the most positive replacement ratios globally has come from ExxonMobil's tremendous deepwater find offshore Guyana, which stands at over 5Bbbl currently.
"Rystad's annual review of oil reserves provides a consistent grouping of recoverable oil into proven reserves and probable reserves, as well as contingent and prospective recoverable resources," it said, noting that it uses the standard Society of Petroleum Engineers to estimate reserves and resources to compare all fields consistently across the globe, in both OPEC and non-OPEC nations.
It also noted some nations, such as Venezuela "report official reserves apparently including yet undiscovered oil, while others like Brazil and Norway officially report conservative estimates covering only existing fields."
Therefore using the SPE standard leads to an estimate of that the world's proven oil reserves, or 1P, total 386Bbbl, which it says is 25% that reported in BP's Statistical Review.
It also posited the possibility of Saudi Arabia changing its reporting methodology as it's upwards revision of 10% didn't match increase in activity.
On the other hand the 20% revision to US official reserves "is due to higher reserves reported by the operators and is based on more stringent rules from the US Security Exchange Commission," head of analysis Per Magnus Nysveen said.