school energy&environment

Difficult recovery

The productivity of an oilfield depends on different factors, such as the permeability of the rocks of the reservoir, the pressure inside the oilfield , or the viscosity and density of the hydrocarbons that it contains: because of these limiting factors it is not possible to extract all the hydrocarbons in a reservoir, but only a percentage of the same. The “recovery factor” is an important index that makes it possible to evaluate the percentage of hydrocarbons that can be extracted in an economically profitable manner. Maybe not many people know that with the most well known and economical technologies that are currently in use, the percentage of recovery is surprisingly low: it rarely exceeds 50%. This means that in the known fields there is more or less the same amount of hydrocarbons as the amount extracted in the history of oil exploitation: an enormous quantity that, if made available in some way, would enable us to shift further the dreaded moment in which the reserves of fossil fuels shall inevitably finish.
Furthermore, till date, hydrocarbons have been available in sufficient amounts to cater to the demand, and only the best quality hydrocarbons, which are lighter and more liquid, have been extracted and utilized: a very large part of the hydrocarbons does not have characteristics that are suited for the refining process, as they are too dense, too heavy, too viscous or rich in unwelcome impurities, such as sulphur or heavy metals. However our economy and our energy production are necessarily still based on fossil fuels, and the need to dispose of this (for the time being) essential source of energy has intensified research and development programmes, thus leading research institutes and the principal oil companies to pay attention to what some already define (light-heartedly, but not seriously…) the “bottom of the barrel”.