Reserves and resources are the volumes of oil, gas and other hydrocarbons that are estimated to be commercially recoverable from the bedrock at our licences. For a quantity of hydrocarbons to be classified as reserves the decision must be made that the accumulation will be developed and put into production within a reasonable timeframe. The reserves are divided into two groups, proven and unproven reserves. In turn, the unproven reserves are divided into probable and possible reserves.
Proved reserves (1P)
Proved reserves are those quantities of petroleum which can be estimated with reasonable certainty (more than 90 percent) to be commercially recoverable from known reservoirs and under current economic conditions and operating methods. If deterministic methods are used, the term reasonable certainty is intended to express a high degree of confidence that the quantities will be recovered. If probabilistic methods are used there should be at least 90 percent probaility that the quantities actually recovered will equal or exceed the estimates.
Probable reserves (2P)
Probable reserves are those unproved reserves which are more likely than not to be commercial recoverable under current or future economic conditions. When probabilistic mehtods are used, there should be at least a 50 percent probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable reserves.
Possible reserves (3P)
Possible reserves are reserves that are less likely to be available for extraction. When probabilistic mehtods are used, there should be more than 10 percent probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable plus probable reserves.
Other quantities are designated as resources. All estimates of resources and reserves involve a certain degree of uncertainty, which is primarily due to the geological data available at the time of appraisal and the interpretation of this data. Resources are therefore divided into various categories depending on the relative uncertainty that exists.
About Contingent and Prospective Resources
Contingent Resources are those quantities of petroleum estimated, as of a given date, to be potentially recoverable from known accumulations using established technology or technology under development, but which are not currently considered to be commercially recoverable due to one or more contingencies. Contingent resources are divided into three different classes, 1C, 2C and 3C, which in theory will become 1P, 2P and 3P respectively when contingencies are removed.
Prospective Resources are those quantities of petroleum estimated, as of a given date, to be potentially recoverable from undiscovered accumulations by application of future development projects. Prospective resources have both an associated chance of discovery and a chance of development. Prospective Resources are further subdivided in accordance with the level of certainty associated with recoverable estimates assuming their discovery and development and may be sub-classified based on project maturity.