Volumetric data is from the 3D seismic and gives an indication how big the reservoir is.
Key parameters for the volumetric data are:
1. Gross volume of the reservoir (length x width x height); this number is mostly filled with rock
2. Voids in the reservoir that could be filled with oil or gas, where voids are created by fractures and porosity
3. Depth and location of the reservoir
With this data a P50 can be calculated, and a drill plan created. If the P50 reservoir size was X barrels of oil, then that means there is a 50% probability the reservoir is at least that big.
Zion has a P50 number and I'm sure passed it to the Ministry of Energy.