Friday, March 25, 2011

Complete story of BLACK-GOLD (Oil and Gas)

CRUDE OIL (complex mixture) is commonly known as black gold. Today the war in this world is of black gold and future wars will be on energy sources. Sometime the question comes in mind when we purchase oil and gas from fuel stations for our vehicles or for any other usage that from where it came to us in this form of gasoline (petrol) or natural gas and what processes and people are involved behind the scene in the production of oil and gas from subsurface.
Story of oil and gas is as old as creation of our planet (Earth) which is 4.6 billion years ago. Many scientists and researchers propose different concepts and theories about the origin of petroleum but most commonly and widely accepted theories are only two

1. Organic
2. Inorganic

The scientists who support organic theory believe that oil and gas forms beneath the earth through different processes and mechanisms related to life (living things). According to these scientists oil and gas forms when living organisms (Plants and Animals) died millions of years ago and deposited at the bottom of ancient rivers and seas in the form of layers, the process known as sedimentation. After deposition of many layers, pressure of layers and heat inside the earth turned the animals and plants into viscous material known as kerogen (large complex organic molecular structure). Then due to temperature differences kerogen is converted into oil and gas. After these complex processes and mechanisms oil and gas migration begins and finally the oil and gas are going to accumulate into petroleum traps. Traps are just like container that are capable of holding something e.g. oil, gas, water or any thing. Died animals generate oil and died plants generate gas. This theory is widely accepted as compared to any other theory because the petroleum reserves of the world predicted from this theory are most accurate.

Inorganic theory first put forward in early 1800s. Inorganic theory is not common and the petroleum reserves predicted from this theory are greater in amount as compared to organic theory. The theme of inorganic theory is that the petroleum is left over from the formation of solar system or was formed later deep with in the earth. Due to presence of hydrogen and impurities in crude oil, scientists support this theory. Geologists that support inorganic theory also believe that it explains why petroleum taken from a large area is often chemically similar even though the formations where it was found are made of different type of rocks of different geological ages.

Conforming the presence of petroleum and extracting it from subsurface is not a job for every one. Mainly there are four departments involved

1. Geology
2. Reservoir
3. Drilling
4. Production

Geology is the study about earth. Geologists survey the earth and find the presence of hydrocarbons (oil and gas) through different techniques mainly seismic survey. Finally geologists indicate the point of drilling.

Reservoir is just like pool and an oil reservoir is just like pool or pond of oil. Reservoir engineers work in conjunction with Geologists and the main work of reservoir engineer is to estimate the amount of recoverable hydrocarbons from reservoir.

Drilling is the technique to make a hole. Drilling the oil and gas wells is the toughest job because the driller has to go hundreds of thousands of meters inside the earth where extreme temperatures and pressures are present which are most difficult to handle. Drilling engineers goal is to hit the target where oil and gas is present inside the earth and make clear path between the subsurface and surface for production of crude oil.

Finally the production engineers are going to handle pressures of oil and gas which is coming from subsurface and production surface facility is installed. The main equipment of surface facility is X-mass tree (Assembly of valves). Pressure is handle through different assemblies of valves and chokes and finally crude oil is transported through pipe lines, bouzers etc to Refinery.

Refinery is the final stage of crude oil processing. As we know crude oil is complex mixture. In refinery crude oil is bifurcated into different products e.g. Diesel Oil, Gasoline (petrol), Natural Gas etc due to temperature differences. After bifurcation of crude oil the role of marketing begins and refinery sells crude oil products to industries, fuel stations, power plants etc.

Article written by Engineer Fahad.....

Purpose of this article is to give idea about crude oil production to non technical person

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