Here are some definitions that should help us to understand the NR, extracted from the

Petroleum Resources Management System

Sponsored by:

Society of Petroleum Engineers (SPE)

American Association of Petroleum Geologists (AAPG)

Commercial: When a project is commercial, this implies that the essential social, environmental and economic conditions are met, including political, legal, regulatory and contractual conditions. In addition, a project is commercial if the degree of commitment is such that the accumulation is expected to be developed and placed on production within a reasonable time frame. While 5 years is recommended as a benchmark, a longer time frame could be applied where, for example, development of economic projects are deferred at the option of the producer for, among other things, market-related reasons, or to meet contractual or strategic objectives. In all cases, the justification for classification as Reserves should be clearly documented.

Sub-Commercial: A project is Sub-Commercial if the degree of commitment is such that the accumulation is not expected to be developed and placed on production within a reasonable time frame. While 5 years is recommended as a benchmark, a longer time frame could be applied where, for example, development of economic projects are deferred at the option of the producer for, among other things, market-related reasons, or to meet contractual or strategic objectives. Discovered sub-commercial projects are classified as Contingent Resources.

Contingent Resources:Those quantities of petroleum estimated, as of a given date, to be potentially recoverable from known accumulations by application of development projects but  which are not currently considered to be commercially recoverable due to one or more contingencies. Contingent Resources are a class of discovered recoverable resources.

Recoverable Resources: Those quantities of hydrocarbons that are estimated to be producible from

discovered or undiscovered accumulations.