Oil Drilling

Many years ago, vwhen most people got their water direct from wells , they were sometimes annoyed by a viscous, dark liquid which came out of the ground and contaminated the water. It smelt bad and was extremely dirty. Most people thought it was a nuisance. Today we have a rather different opinion about this substance known as crude oil.

In 1855, a young teacher at Yale University, Benjamin Silliman, became interested in crude oil. He soon found that it could be used as a fuel for heating and lighting and as a lubricant. So he asked his friend Edwin Drake, a railway man, to try to produce this oil on land. Drake tried to collect the oil, which was seeping to the surface, by digging a large hole. This was not successful and he decided to try drilling. Suddenly, as he was drilling the hole，oil began to gush out in a great stream. The first oil well had started production and the age of oil was just around the corner.

Most scientists believe that crude oil is formed by the decomposed remains of billions of tiny plants and animals which lived in the sea millions or hundreds of millions of years ago. When these organisms died, they decayed and over millions of years layers of slime formed on the ocean bed; with the pressure of movements in the earth's crust and the heat this pressure caused, these layers were converted into petroleum. Only 120 years ago，nobody would have wasted his time trying to dig it up.

Now, 120 years later, the list of crude oil fractions (things which make up the mixture called crude oil) and by-products is nearly endless ：petrol for cars, diesel oil for trains, buses and lorries; aviation fuels, lubricating oils for all engines, heavy oils for power stations and ships, asphalt for roads, petrochemicals for plastics, synthetic fibres and even for synthetic food products,etc. Today, a world without petroleum products is almost unimaginable.

In 1971, the world produced 17.25 billion barrels of oil (1 barrel = 42 U.S. gallons). But already in 1973 car drivers in many countries found that sometimes there was not enough gasoline for their cars or enough fuel to heat their homes. And so the search for more and more oil continues. It is being drilled for in the frozen wastes of Alaska and Siberia as well as in the deserts of Africa and the Middle East. And not only on land, but also at sea.

The first oil from the sea was produced some decades ago by the off-shore drilling rigs. But men are now also drilling in the cold, deep North Sea (deep-sea drilling).

It may seem an easy job to drill holes in the land areas of the earth, but even an exploratory well may be over 3000 metres deep! The drillers may have to drill through very hard rock, and when they have drilled part of the well they will probably have to take all the drill pipe out to change the drilling bit at the lower end. It is the bit which eats through the rock and, although it is very sharp and has 132 cutting edges, it quickly wears out. Then, after drilling 3000 metres, they may find nothing! Or, if they strike oil，it may gush out so powerfully that workers are injured and equipment damaged. A spark might ignite the oil vapour and cause a fire which would burn so fiercely that it could only be extinguished by explosives. In the past, such accidents were frequent, but techniques have been developed to help avoid them.

But imagine working on a deep-sea drilling rig, which is really a huge platform, in a storm with 50 or 60 metres of water below you! This is how men are working at this moment 100 miles off the coasts of Scotland and Mexico. All their food and drink must be brought by boat or helicopter and，if oil is founds pipelines must be laid by divers on the ocean，bed to carry the oil to land.

The petrolium which comes out of the ground cannot really be used for anything. It must first be refined. Refineries are huge "factories" where crude oil is separated into "fractions" which are commonly known as gasoline, kerosene, diesel oil, lubricating oil and fuel oil. Then the fractions must be distributed by pipeline or tanker to the final distributors, such as filling stations (for gasoline and diesel oil), which sell it to the ultimate users.