Reserves-to-Production Ratio (RPR) is the life of gas (oil) field production. It is calculated by dividing current reserves of A + B + C1 categories for the beginning of some year by this year's production in an administrative oil-and-gas-bearing region and/or production enterprise. The RPR dynamics in different regions is similar, and its levels reflect peculiarities of resources development. The RPR is at its maximum in the course of reserve preparation in the largest fields and at the beginning of production. In the process of reserves involvement into the development the production increases; as a rule, reserve preparation speed declines, which causes the RPR decrease. At a high rate of initial resources use production drawdown takes place. It is considered that the optimal character of oil and gas resources development both countrywide and in separate regions corresponds to 35–40 RPR. The RPR increase at the final stage of resources development in oil-and-gas-bearing regions under conditions of production drawdown indicates the actual life of field production decline.