school energy&environment

Non conventional reserves

It is not easy to estimate what lies underground, however it is believed that in the sedimentary rocks worldwide, there are probably 1.8 x 10¹² cubic metres  (approximately  12 x 10¹² barrels) of liquid oil. Liquid hydrocarbons, even though they all belong to the same family, differ from one another. They are made up of compounds with different chemical and physical characteristics: oils, heavy oils, tar  and very heavy oils. The oils of the best quality are the less viscous ones, and are called “conventional” oil (or petroleum): in fact these hydrocarbons can be extracted with conventional methods, with technologies that have already been developed, and that are widely utilized since decades all over the world, with relatively low costs, which are therefore very convenient.
However, out of all the estimated reserves, conventional oil is only a small part (approximately 0.5 x 10¹² m³): the more consistent part (approximately 1.3 x 10¹² m³) consists of oil with a high viscosity, that is less valuable and more difficult to extract. An analogous quantity of organic material, a potential source of hydrocarbons, is trapped in the form of kerogen (a precursor of petroleum) in particular rocks such as oil shale and tar sand, however this is mostly beyond our range of utilization, at least at present.
Since the reserves of conventional oil are inexorably decreasing, research is pointing towards the exploitation of the more viscous hydrocarbons. These are known as “non conventional” hydrocarbons because, in order to extract them, special techniques are required, such as extraction by mining, appropriate processing of the rocks that contain these hydrocarbons, or procedures  to decrease their viscosity, so that it is easier to extract them. Furthermore, all these “special” hydrocarbons  require prior processing before being sent for refining. Therefore there are potentially enormous reserves, but for the extraction and production of these hydrocarbons, much more complex technologies are required, and these are still in the developmental stage, and due to the additional costs these are not competitive as yet. However, the situation is rapidly changing and the future of oil research is increasingly oriented towards the “non conventional” hydrocarbons.