school energy&environment

Some history

Asphalts, tar  and heavy oils are not a recent discovery, on the contrary, it may be said that these were the first hydrocarbons to be used by man. Since the dawn of human civilization, in fact, these were used for the most varied purposes: as a sealing and waterproofing material for boats and the roofs of houses, as a glue, as fuel for oil lamps and lights, and as a medication for wounds.
From the very beginning of industrial exploitation of oil, it was noted that only a very small part of the hydrocarbons present in a reservoir could flow out naturally because of the pressure  in the oilfield: which however decreased gradually as the contents of the oilfield were emptied out, and therefore from the very beginning, the need arose to study techniques that could artificially increase the pressure so as to facilitate the oil extraction procedures. The most common technique consists in injecting gas and water in the reservoir, that help to move the oils with a lower viscosity towards the wells.
However, notwithstanding these expedients, the heavier and more viscous oils  cannot be moved and at least 50% of the hydrocarbons remains in the reservoir. For this reason a large number of oil reservoirs have been abandoned, because they were considered unproductive with the “normal” techniques, although these oilfields still contain a very large quantity of viscous hydrocarbons. Now that the conventional  oil reserves are becoming depleted, at the end of the 20th century,  research has been started to find techniques that enable the extraction and utilization of these “difficult” hydrocarbons.
Heavy hydrocarbons are not economical, but they are abundant and in the 21st century they will be a very important source of fossil fuel.
Experimental processes to distil hydrocarbons from rocks such as oil shale or tar sand were studied even far back in the 18th century, to extract asphalts, tar and oils for the lamps.
Of course there are a number of historical curiosities: for example, the so-called  “saurolo”  used to be extracted from a rocky formation known as “scisti bituminosi di Besano” (Besano tar shale),  in the province of Varese. This area was well  known for the discovery of  perfectly preserved  fossil remains of fish and large reptiles.  The heavy Saurolo  oil  was thought to be some kind of “dinosaur distillation”, and was considered  a very powerful, multipurpose medication!  In the second half of the 19th century Saurolo,  which is very similar to Ichthyol (that was produced in Tyrol, which is now created artificially),  was produced on an industrial scale and marketed by the pharmaceutical companies to cure skin diseases. In particular, it was used to cure cases of dermatitis reported by Italian soldiers who fought in the African campaigns.  At the site, already in the 18th century,  there was a mining activity to extract oil shale,  that was used as fuel for lighting purposes. And starting from 1830,  a new project was begun for the extraction of gas for public lighting of the city of Milan.
After this pioneering and experimental phase, researches on non conventional hydrocarbons started again in the Eighties, with  an increasing allocation of funds . New technologies were used for the extraction, production and processing of the viscous oils, with important technological innovations that made exploitation of this resource increasingly profitable in terms of  the percentages recovered and costs.