crude oil - origin of bitumen part 1

The properties of bitumen depend on the properties of the crude oil from which it is manufactured and the treatment during manufacturing. There are similarities in relation to elemental composition between crude oil and bitumen. Nitrogen and sulphur contents are increasing, due to higher concentration of these elements in heavier compounds and hydrogen is decreasing, due to extraction of lighter hydrocarbon chains during refinery. The metal content varies in crude oil from 0,01 to 0,04wt%. About thirty different metals are found in different crude oils. The most common are vanadium, nickel, iron, zinc, mercury, boron, sodium, potassium, calcium and magnesium.

The origin of crude oil, base on the organic petroleum hypothesis, is the biomass (special microorganisms like phytoplankton) that inhabited the seas and oceans a long time ago. The concentration of organic material increases with depth, so the highest concentration is found at the bottom. Due to mineral accumulation these organic material can be trapped and encapsulated from decomposition. With the build up of additional layers of minerals and the movements of the lithosphere plates, trapped organic material can pass in zones of rift or subduction where the temperature increases by 100 to 400 °C (minimum depth of 2 to 3 km). In that temperature range the dissociation of various compounds takes place and provides the necessary energy for the formation of crude oil.

Nowadays we extract crude oil from those entrapped depositions. The extraction happens under the natural layer pressure, or by pumping. With both operation methods the petroleum layer and added water layer are concurrently extracted. Petroleum and water then form an emulsion. The continuous phase is most frequently petroleum and the discontinuous phase is accordingly water. The emulsion intensifies depending on the extraction method and additionally during transportation through pipes. Further the presence of emulsifiers influences the formation and properties of an emulsion. The used method to dry petroleum depends on the amount and condition of water. Non-stabilized emulsion can be separated by settling methods or by settling with moderate heating. A stabilized emulsion is more difficult to separate. The methods include intense heating, chemical processing, electrical processing or a combination of those methods. Often during drying a desalting takes place, by removing the water with the dissolved minerals (chemical or electrostatic separation at 110 to 160 °C).

After this the crude oil is ready for refinery.