Petroleum / crude oil / natural gas (exploration, production, processing etc.):

Petroleum / crude oil / natural gas (exploration, production, processing etc.):

Petroleum or more commonly known as Crude oil, available naturally below surface of the earth; used by human being as fuel and applicable for production of various chemicals. Modern society heavily depends on Petroleum / crude oil inclusive of natural gas. Crude oil has become most significant fuel and raw material for production of chemicals in present day world. Because of higher demand for hydrocarbons, pressure on exploration, production and further processing of crude oil / natural gas is tremendous and due this the prices of crude oil have touched sky level recently.

The main activities of the petroleum industry are: (a) Exploration of crude oil and natural gas; (b) Production of crude and natural gas; (c) Processing consists of refining crude for gasoline, diesel, lubricants and further production other down stream chemicals by cracking; (d) Marketing and distribution of gasoline, diesel, lubricants and other processed chemicals.

A. Exploration: Petroleum / crude oil / natural gas are extracted mainly from oil wells found in various oil fields spread all over the world. Various methods are employed in exploration of crude and natural gas and to optimize the process techno-economically. Most exploration process depends on highly sophisticated technology to detect and determine the extent of these deposits. Exploration is initiated with gravity survey, magnetic survey to detect large scale features of the sub-surface geology of the area of investigation. More detailed seismic surveys are conducted at the areas of interest (known as leads). Seismic surveys are basically based on the principle of velocity / time taken by sound wave on reflection at various formations of ground strata, as velocity differs at various interfaces. Finally, when a prospect has been identified, evaluated and passes the selection criteria, exploration wells are drilled to know the presence of oil or gas.

B. Oil / gas Production: Next stage after exploration is production or recovery from the oil reservoir identified after exploration. (a) Primary recovery of oil and gas is done when underground pressure in the oil reservoir is sufficient. This pressure forces the oil to bring it to surface. (b) In Secondary oil recovery various techniques are employed, as this is done when pressure is low in the underground oil reservoir. Pumps such as, beam pumps, electrical submersible pumps are used to bring the oil to the surface. Water injection, gas lift (when CO2 or air is used) and natural gas re-injection are some of the methods also applied when required. (c) Tertiary oil recovery is mainly done to maintain recovery from very low pressure oil reservoir; by reduction of viscosity of underground oil by injecting heat, vapour, surfactants, solvents or miscible gases (CO2).

C. Processing of crude: Processing of crude is done in oil refineries; where more useful petroleum products such as gasoline, kerosene, diesel, LPG (liquefied petroleum gas) etc., are produced by a process known as fractional distillation. Products having lower boiling point leaves from top and higher boiling point products leave the fractioning column at the bottom. Therefore, light distillates are LPG, gasoline, naptha; middle distillates are kerosene, diesel and heavy distillates including residuum are fuel oil, lubricating oils, wax and tar.

D. Petroleum is the major source of organic chemicals. In petrochemical industry major chemicals are derived from two constituents of crude oil – Xylene and Naptha. These chemical raw materials are broken down into basic chemicals such as Butadiene. Basic chemicals are made into finished chemicals or chemical products either direct conversion or through an intermediate. For example, butadiene can be directly made into synthetic rubber or butadiene may be processed into an intermediate such as acetone and later acetone may be used for manufacturing other finished polymers.

• Raw material – Naphtha, Xylene.

• Basic chemicals – Butadiene, Ethylene, Propylene etc.

• Intermediates – Acetone, Phenol, Acrylonitrile, Vinyl acetate, Ethanol etc.

• Polymers – PVC, Polyester fiber, Polystyrene, Polyethylene etc.

E. Major Crude oil and natural gas producing countries are: (a) Saudi Arabia (an OPEC country); (b) Russia; (c) USA; (d) Iran (an OPEC country); (e) China; (f) Mexico; (g) Canada; (h) UAE (an OPEC country); (i) Venezuela (an OPEC country); (j) Norway; (k) Kuwait (an OPEC country); (l) Nigeria (an OPEC country); (m) Brazil; (n) Algeria (an OPEC country); (o) Iraq.