Photo How is oil formed ?
23 Aug 2018

How is oil formed ?

Oil formation is a process that is staggered millions of years. The most widely used energy in the world undergoes complex natural procedures from organic matter to the oil field.

Formation from an organic matter

The accumulation of organic matter

Organic matter from living things forms biomass. The remaining parts of this living mass are deposited in the seabed where they are mixed with mineral matter. The accumulation of these materials forms hundreds of meters of layers of sedimentation. Buried at about 1,000 meters, sedimentation sludge is transformed into kerogen (composed of carbon and hydrogen) under the influence of anaerobic bacteria.

From kerogen to oil

Then, beyond 1,000 meters deep, the sedimentary layers undergo solidification in impermeable rock: the bedrock. It traps kerogen. In addition, the temperature increases by 3 ° C every 100 meters. Thus, at 60 ° C and 2,000 meters deep, the kerogen undergoes a chemical decomposition by heating by removing nitrogen, oxygen and sparing CO2, water and hydrocarbons. The liquid hydrocarbon mixture constitutes the crude oil.

The formation of deposits

Primary migration

Oil is a readily exploitable raw material. Nevertheless, its extraction depends on the characteristics of the deposit influenced by migration phenomena. This latter brings indeed to the formation of deposit. In addition, there is primary migration. This migration occurs when the crude oil implanted in the source rock moves to another reservoir rock. This phenomenon results from the increase in the pressure of the bedrock during its burial.

Secondary migration

Oil expelled during primary migration often rises to the surface. However, some geological formations, in this case a layer of salt prevents this displacement. Thus, the oil migrates to the lower permeable layer to create another reservoir rock. In this tank, the gas floats above crude oil and water. Moreover, the 40% of the hydrocarbons retained in the source rock constitute shale oil.

Oil traps

The different oil traps

The reservoir rock displays an oil trap structure. In addition, the types of oil traps are characterized according to the deformation of rocks during geological phenomena. Structural traps or anticlinal traps display vaulted rocks due to land movement. In addition, stratigraphic traps are characterized by a reservoir rock separated in two by the rise of a mass of salt.

The location of oil deposits are in the Middle East, America, Europe, Russia and Central Asia. In addition, Africa also has a high potential for hydrocarbon deposits. Originally from Tunisia, Tarek Bouchamaoui has also obtained a license to operate in Egypt. Thus, the businessman Tarek Bouchamaoui is shared between Egypt and Tunisia to supervise the exploitation of oil.