Category:Resource Measures
From Eurêka
Recovery factor Proportion of economically accessible reserves that can be extracted, e.g. in the case of petroleum in place, the amount that can be extracted is related to the conditions of the reservoir, the composition of the crude oil and the method by which it is extracted.
Exploitation-history projection Method of forecasting the amount of a mineral resource available in any area on the basis of a discovery-depletion cycle or exploitation curve based on the history of production. The method had been used extensively in the case of oil and natural gas.
Geologic-analogy method Method of estimating undiscovered mineral reserves involving projections based on rates of production at deposits currently worked to similar geological structures in other areas. It is applied particularly to oil and gas reserves using either, (1) The average oil-in-place content of productive sedimentary masses, or (2) The average number of barrels produced per unit rock volume in productive basins, or (3) The finding rate per unit of exploratory footage drilled in productive environments, to estimate the reserves of potentially productive prisms of sedimentary rock.
Discovery-depletion cycle (Exploitation cycle; Production depletion curve) Concept applicable to the exploitation of non-renewable resources, especially minerals, which recognizes that the limit of use of such a resource is a finite quantity. The discovery-depletion cycle represents a generalized exploitation pattern and is based on observed relationships over time between the variables of cumulative discoveries, cumulative production and proven reserves. The cycle is experienced for the resource as a whole, as well as for particular mining districts and individual mines. The passage of the cycle may be extremely erratic and the length of the cycle highly variable. Six stages are recognized:
- Discovery Prospecting and discovery of a resource and its evaluation.
- Development Creation of the facilities and infrastructure to extract the resource.
- Rapid expansion Period when the discovery rate outstrips production rate.
- Mature peak production Time when the rate of discovery of new reserves falls.
- Decline Reserves are depleted and production falls. In general terms consumption also falls as costs rise and alternatives are sought out leading to a new cycle elsewhere
- Resource exhaustion Limit of economic exploitation of a resource and cessation of its extraction.
Sustained yield (Demand curve; Maximum sustainable yield; Sustainable capacity; Sustainable yield curve) Concept of steady state in which harvesting occurs at a constant rate and the level of the resource stock or the distribution of ages in time-independent. The continuous production at a given level forever of a renewable resource in which no more is harvested than is added to by growth. The concept is applied mainly to the management of forests and the fishing industry. Under this concept, maximum net social revenue, if not reached, is more closely approximated. The amount of timber which is harvested each year from a single management area in order to make the transition to sustained yield is called the allowable cut.
Critical zone Point in the depletion process which is so far advanced that natural recovery of the supply flows fails to take place, even when all exploitation has ceased. In addition to biological resources, it is possible that some soils and aquifers may also have critical zones.
Diminishing returns Before absolute physical exhaustion occurs, there ought then be a age when the marginal physical product starts to fall and diminishing returns (or output) per labor unit set in. Although lower-grade ores and deposits occurring at greater depths in areas less accessible to markets are being exploited, technological innovation appears to have postponed diminishing returns in many cases.
Static life index Life of each mineral can be crudely calculated by dividing current reserves by the present annual consumption of that mineral.
Recovery Proportion of coal, iron, etc., mined from a mineral deposit.
- Primary recovery
- Secondary recovery
