Based on context may mean either Estimated Ultimate Oil Recovery (EUOR) or Estimated Ultimate Gas Recovery (EUGR).
In both cases it means refers to the maximum recoverable volume of Hydrocarbon Reserves (HCR).
The percentage of Estimated Ultimate Recovery with respect to the total Surface Tank Hydrocarbon Initial In Place (STHCIIP) is called Estimated Ultimate Recovery Factor (EURF).
See Also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology / Petroleum Reservoir / Petroleum Reservoir Fluids / Hydrocarbon Initial In Place (HCIIP)
[ Estimated Ultimate Oil Recovery (EUOR) ] [ Estimated Ultimate Gas Recovery (EUGR) ]