Crude oil (whichis commonly known as petroleum) is a naturally occurring liquid, non-renewablesource of energy found within the earth’s crust comprising of hydrocarbons (usuallythe primary component), organic compounds (like nitrogen, oxygen and sulphurthat make up between 6%-10%) and small amounts of metal (like iron, vanadium,copper and nickel that account for less than 1% of the total composition). Crudeoil even after the appearance of other forms of energy such as water, wind andsolar power has remained the main source of energy all over the globe.
Thisessays aims to give clear, detailed and specific information on the formationof crude oil, its refining; components, properties, uses of crude oil and itseffects on the environment. By the end of this essay you will vividlycomprehend why crude oil is important not only to the other energy sector butalso to our lives in general. It is a backbone to most countries such as Libya,Venezuela and Saudi Arabia. MAIN BODYTheFormation of Crude oilThe crudeoil extracted over the past century was formed millions of years ago, over 500million years and some of the newest deposits formed over 50 million years ago.Small marine animals and plants died millions of years ago and sunk to theocean floor or seabed where they decomposed and got buried under layers of sandand silt.Due tolack of oxygen on the sea bed, the bacteria could not decompose the remainscompletely.
The partially decomposed remains, overtime formed into a large masswith the weight of sand and silt that was building up pressing down on themcausing them to be compressed into a thinner layer.Theimmense pressure created by heavy layers of sediments and natural heat from theearth changed the chemical composition of the remains through a process calleddiagenesis into a waxy compound called kerogen and then, with increased heatinto a liquid through a process called catagenesis. The oil is forced out fromits original area of formation and travels upwards through the cracks and gapsin the shale formation until it reaches a new impermeable rock formation calledreservoir rock. The oil lays trapped here until it is discovered and extracted.
Crude OilRefiningTherefining process depends on the chemical processes of distillation (separatingliquids by their different boiling points) and catalysis (which speeds upreaction rates), and uses the principles of chemical equilibria. Chemicalequilibrium exists when the reactants in a reaction are producing productswhich are recombined again into reactants. By altering the reaction conditions,the amount of either products or reactants can be increased. Refiningis carried out in three main steps.Step 1 -Separation The oil is separated into its constituents by distillation, and someof these components (such as the refinery gas) are further separated withchemical reactions and by using solvents which dissolve one component of amixture significantly better than another. Step 2 – Conversion The various hydrocarbonsproduced are then chemically altered to make them more suitable for theirintended purpose. For example, naphthas are “reformed” from paraffinsand naphthenes into aromatics.
These reactions often use catalysis, and sosulfur is removed from the hydrocarbons before they are reacted, as it would’poison’ the catalysts used. The chemical equilibria are also manipulated toensure a maximum yield of the desired product. Step3 -Purification The hydrogen sulfide gas which was extracted from the refinery gasin Step 1 is converted to sulfur, which is sold in liquid form to fertilisermanufacturers. The plant at Marsden Point also manufactures its own hydrogenand purifies its own effluent water. This water purification, along with gas’scrubbing’ to remove undesirable compounds from the gases to be dischargedinto the atmosphere, ensures that the refinery has minimal environmentalimpact.