IVZ media thread, page-7261

Resources to Reserves....

Prospective resources are quantities of hydrocarbons that are estimated to be recoverable from undiscovered accumulations through future development projects.

Reserves are quantities of known accumulations that are evaluated as commercial on both technical and economical grounds at a given date.

Prospective resources are subject to a higher degree of uncertainty than discovered resources because they are undiscovered.
They have a wide range of volume uncertainties and a high risk of not being present in reality.

During the exploration stage, prospective resources are categorized by volume uncertainties using abbreviations like P90-P50-P10 and 1U, 2U, and 3U.

Companies may choose to voluntarily report their views of prospective resources, but they are not usually required to do so.

Discovered (or known) accumulations are classified as Contingent Resources or Reserves

Yet-to-be-discovered accumulations are classified as Prospective Resources.

Commerciality differentiates between Contingent Resources and Reserves.

Reserves are defined as those quantities of petroleum which are anticipated to be commercially recovered from known accumulations from a given date forward.

https://www.spe.org/en/industry/petroleum-resources-classification-system-definitions/

IVZ has some way to go yet ? Oilf.