Reserve Life Index

What is this formula?

The Reserve Life Index (RLI) estimates how many years a resource reserve will last if production continues at the current extraction rate.

It is one of the most widely used indicators in mining, petroleum engineering, natural gas production, and resource planning.

A larger RLI indicates a longer expected production life, while a smaller value may indicate reserve depletion risks or the need for new discoveries.

When to use it

Use this formula when evaluating:

- Mine life estimation

- Oil and gas field longevity

- Resource sustainability studies

- Strategic extraction planning

- Reserve reporting and investment analysis

Example

A copper mine contains recoverable reserves of 120 million tonnes.

Data:

R = 120,000,000 t

E = 4,000,000 t/year

Formula:

RLI = R / E

Substitution:

RLI = 120,000,000 / 4,000,000

Result:

RLI = 30 years

The mine can theoretically continue operating for approximately 30 years if production remains constant.

Applications

- Mining engineering

- Petroleum engineering

- Natural gas production

- Resource economics

- Government resource assessments

- Long-term production forecasting