Discovering an Oil Field

Wonderful Metamorphosis

Until the beginning of the twentieth century the oil business was really the kerosene business. A little oil was being turned into lubri­cants, and some asphalt was used to surface city streets; but the manufacture of kerosene for lighting lamps was the refiner's main concern. He was hampered, however, by a by-product which nobody wanted and which has a nasty habit of getting into kerosene and blowing people through the roof when they tried to light their lamps. This by-product was called gasoline. It seemed to have only one possi­ble use: druggists sold it in bottles to housewives who wanted to remove grease spots from clothing. Gasoline's days of unimportance were nearly over. Men like Elwood Haynes and Henry Ford were tinkering with a new kind of engine. Water power and steam had been the only sources of power to run machines. Now these men developed the internal combusion engine. This ran by means of series of explosions which drove a piston down into a cylinder. And what was that was exploding inside the cylinder? Gasoline, that nuisance of the kerosene refinery! Soon the gasoline engine was running all kinds of machines. Auto­mobiles, buses, trucks, tractors, boats, pumps, farm machinery, all us­ing gasoline, were opening up possibilities of a whole new life. Now the hard work which men had always performed could be done better and more quickly by machines. For about 25 years after Drake's first well began producing, most of the oil in the United States came from Pennsylvania. By 1886, new fields were discovered in Colorado, Kan­sas, Texas, Oklahoma, and New Mexico. By 1920 oil fields were devel­oped as far west as California. Every year new strides are being made. While oil fields were being opened all over the United States, geologists in other countries were also busy tracking down petroleum, the black gold. European wells began producing in Germany and Ro­mania, and in Russia jiear the Caspian Sea. Vast new fields were brought in around the Arabian Gulf, in Iraq, Iran, and Kuwait. The sheiks who ruled there were made richer than the fabulous sultans in the '"Thousand and One Nights". In Indonesia lakes of oil were found. In South America, Venezuela produces millions of barrels a year. Can­ada can boast of not only the most northerly oil field but also the world's largest known oil deposit. Today more and more fields are being discovered in all parts of the globe. Along with the enormous increase in the use of oil has come great expansion of the natural gas market. Natural gas, often found with the oil in an oil pool, is often discovered by itself. The well producing it is called a gas well. Gas pipelines bring it from the field to our great cities, where it is piped direct to industrial plants and to home gas stoves.

Discovering an Oil Field

Since 1850, the search for oil has been endless. Generally, there is nothing above ground which can show exactly where oil might lie

be­low. The oil explorer today has to be a detective tracking down all the clues science can give him. He is helped by many different teams of experts, but the decision to drill is still a big risk. Do you know what are the people who try to determine where oil may be found? Can you explain what makes oil exploration a risky business?

The people who try to determine where oil may be found are called geologists. They try to unlock the secrets beneath the earth's surface by studying the formation of rock strata. They have learned a good deal about where oil is not and somewhat less about where it is. They know that three things must exist fairly close together beneath the earth's surface at any place where oil is likely to be found.

First, there must be a bed of what once was undersea mud in which bodies of billions of sea creatures had perished. The geologist detects this bed by the shells and skeletons left imbedded in the rock.

Second, a layer of porous rock - sandstone, limestone, or dolomite - must be near enough so that oil, forced by water pressure, can enter the pores. Unless it is blocked by something, oil may travel a long way through the porous rock, called oil sand. It may even spread out.

In the third place, the layer of oil sand must be surrounded by a layer of dense rock through which the oil can't be squeezed no matter how high the water pressure is. Try to imagine, if you can, making a huge jelly sandwich by squeezing runny jelly into six or seven layers of unevenly cut bread; parts of the bread soft, and parts hard and crusty. If, when you finished, you cut off a slice, you would see, that the jelly was in uneven spots here and there, throughout the whole sandwich. Some would have soaked into the soft bread up to where it was stopped by the crusty parts. Oil is caught in traps under­ground in somewhat this same way. It soaks into the soft rock, and is stopped by hard layers. Traps are what oil explorers try to find.This formation which blocks the oil and keeps it from travelling any far­ther, may be an anticline, a fault, or a stratigraphic trap.

An anticline is a place where the earth's crust was once pushed up to form an arch. This arch may now be buried far below the earth's surface. Oil travelling along a sandstone stratum flows to the top of the arch. There it is imprisoned by water pressure from below, and there it will stay forever, until a driller can find and tap it.

A fault is a place where the earth's crust has slipped, breaking the layers of underground rock. Thus a layer of dense rock may have

been pushed up or down, blocking a layer of sandstone. When the oil seeping through the sandstone reaches the rock layer it finds a dead end. Unable to move ahead because of the hard rock, it cannot move back because of water

pressure behind it. So a pool is formed.

A stratigraphic trap is a formation of two layers of dense rock separated by a layer sandstone, like a sandwich. Some­where the two layers of hard rock pinch together and keep the oil in the sandstone from going farther. This also forms an oil pool.

Date: 2015-12-11; view: 884