Around 300 BC, Alexander the Great supposedly used burning oil or "petroleum" to frighten the war elephants of his enemies.
Marco Polo during his trips in the 13th Century recorded oil seeping from underground in the Caspian Sea region. Inscriptions found by archeologists indicate that oil and asphalt (a hard form of oil) were even used in 4000 BC in this area. Asphalt was also used by the ancient Egyptians to embalm mummies.
Ruins of early ships found by archeologists indicate that those vessels were caulked (cracks sealed to keep water out) with a form of asphalt, sometimes called bitumen or pitch.
In what is now the United States, petroleum was reported by Juan Rodriquez, a Spanish explorer, in 1542 near Santa Barbara, California. Oil residues from surface seepages near Nacogdoches, Texas, were used to repair the boats of the DeSoto expedition in 1593.
Today's oil industry actually began almost 150 years ago -- in 1859. In those days, melting the fat of whales made an oily fuel for lamps and lubricants. However, whale oil had become expensive. A company called the Pennsylvania Rock Oil Company became interested in digging for natural oil. People drilling for salt had encountered oily rocks in Pennsylvania. At first, this "rock oil" had been used as a medicine, but if enough of it could be found, perhaps it might be a cheaper substitute for whale oil.
Digging huge pits, however, was a time-consuming, expensive operation, so the Pennsylvania Rock Oil Company came up with the idea of drilling for oil. Not everyone was convinced, however. One banker who was asked to lend some of the money for the venture remarked, "Oil coming out of the ground, pumping oil out of the earth as you pump water? Nonsense!" However, the Pennsylvania Rock Oil Company was convinced that drilling for oil -- rather than digging for it -- was the way to go. They hired a part-time railroad conductor named Edwin L. Drake to go to Titusville, Pennsylvania and see if he could drill for oil. (Some books call him "Colonel" Drake, but he invented that title only to impress the local townspeople.)
Drake spent almost a year -- from 1858 to 1859 -- getting the money and building the equipment (including a steam engine) he needed to drill. In the spring of 1859, he built the derrick and started to drill. It was slow going. The investors became nervous, and late that summer, they sent a letter to Drake directing that he cease operations pay off his debts and give up.
The letter was slow in arriving at Titusville. Before he got it, Drake had drilled about 69 feet. Then, the drill dropped into an underground crevice and abruptly slid down another 6 inches. Work stopped, but the next day one of the Drakes employees went out to check the drill rig. He peered down into the pipe that had been left in the hole. There, floating on top of water in the pipe, was oil. Drake had struck oil. A new industry was born.
Today, in the United States, the oil industry employs more than 300,000 workers. More than 8,000 companies produce oil in the United States. Oil flows from reservoirs underneath more than 30 States. But in the almost 150 years since Edwin L. Drake drilled the very first U.S. oil well, a lot of oil fields have gone dry. Very little oil, for example, is still produced in Pennsylvania where the industry was born. In places like Texas, Oklahoma, Louisiana, and California, oil fields continue to produce millions of barrels of oil each day. Nevertheless, even these fields are slowing down.
That doesn't mean we are running out of oil, however. It means that we are running out of "easy" oil. There is still more oil left in fields that have been pumping for 20, 30 or even 50 years. To find out the new ways being developed to produce this oil, we must be able to look down an oil well. If you could look down an oil well and see oil where nature created it, you might be surprised. You wouldn't see a big underground lake, as many people think. Oil doesn't exist in deep, black pools. In fact, an underground oil formation - called an "oil reservoir" - looks very much like any other rock formation. It looks a lot like...well, rock.
When reservoir rock is magnified, the tiny pores that contain trapped oil droplets can be seen. Oil exists underground as tiny droplets trapped inside the open spaces, called "pores", inside rocks. The "pores" and the oil droplets can be seen only through a microscope. The droplets cling to the rock, like drops of water cling to a window pane.
How do oil companies break these tiny droplets away from the rock thousands of feet underground? How does this oil move through the dense rock and into wells that take it to the surface? How do the tiny droplets combine into the billions of gallons of oil that the United States and the rest of the world use each day?
Squeezing Oil out of Rocks
Imagine trying to force oil through a rock. Can't be done, you say? Actually, it can. In fact, oil droplets can squeeze through the tiny pores of underground rock on their own, pushed by the tremendous pressures that exist deep beneath the surface. How does this happen? Imagine a balloon, blown up to its fullest. The air in the balloon is under pressure. It wants to get out. Stick a pin in the balloon and the air escapes with a bang!
Oil in a reservoir acts something like the air in a balloon. The pressure comes from millions of tons of rock lying on the oil and from the earth's natural heat that builds up in an oil reservoir and expands any gases that may be in the rock. The result is that when an oil well strikes an underground oil reservoir, the natural pressure is released - like the air escaping from a balloon. The pressure forces the oil through the rock and up the well to the surface.
If there are fractures in the reservoir -- fractures are tiny cracks in the rock -- the oil squeezes into them. If the fractures run in the right direction toward the oil well, they can act as tiny underground "pipelines" through which oil flows to a well. Oil producers need to know a lot about an oil reservoir before they start drilling many expensive wells. They need to know about the size and number of pores in a reservoir rock. They need to know how fast oil droplets will move through these pores. They need to know where the natural fractures are in a reservoir so that they know where to drill their wells.
Today, scientists have invented many new ways to learn about the characteristics of an oil reservoir. They have developed ways to send sound waves through reservoir rock. Sound waves travel at different speeds through different types of rocks. By listening to sound waves using devices called "geophones", scientists can measure the speed at which the sound moves through the rock and determine where there might be rocks with oil in them.
Scientists also measure how electric current moves through rock. Rocks with a lot of water in the tiny pores will conduct electricity better than rocks with oil in the pores. Sending electric current through the rock can often reveal oil-bearing rocks. Finally, oil companies will look at the rocks themselves. An exploratory well will be drilled, rock samples, called "cores", will be brought to the surface. Scientists will look at the core samples under a microscope. Often they can see tiny oil droplets trapped inside the rock.
When companies are convinced that they have found the right underground rock formation that is likely to contain oil, they begin drilling production wells. When the wells first hit the reservoir, some of the oil begins coming to the surface immediately. Many years ago, when oil field equipment was not very good, it was sometimes difficult to prevent the oil from spurting hundreds of feet out the ground. This was called a "gusher". Today, however, oil companies install special equipment on their wells called "blowout preventors," that prevent "gushers", like putting a cork in a bottle.
When a new oil field first begins producing oil, Nature does most of the work. The natural pressures in the reservoir force the oil through the rock pores, into fractures, and up production wells. This natural flow of oil is called "primary production." It can go on for days or years. But after a while, an oil reservoir begins to lose pressure, like the air leaving a balloon. The natural oil flow begins to drop off, and oil companies use pumps (like the drawing at the very top of the page) to bring the oil to the surface.
In some fields, natural gas is produced along with the oil. In some cases, oil companies separate the gas from the oil and inject it back into the reservoir. Like putting air back into a balloon, injecting natural gas into the underground reservoir keeps enough pressure in the reservoir to keep oil flowing. Eventually, however, the pressure drops to a point where the oil flow, even with pumps and gas injection, drops off to a trickle. Yet, there is actually a lot of oil left in the reservoir. How much? In many reservoirs, as many as 3 barrels can be left in the ground for every 1 barrel that is produced. In other words, if oil production stopped after "primary production," almost 3/4ths of the oil would be left behind! That's why oil producers often turn to "secondary recovery" processes to squeeze some of this remaining oil out of the ground. What are "secondary recovery" processes?
It is colorless, shapeless, and in its pure form, odorless. For many years, it was discarded as worthless. Even today, some countries (although not the United States) still get rid of it by burning it in giant flares, so large they can be seen from the Space Shuttle. Yet, it is one of the most valuable fuels we have. Natural gas is made up mainly of a chemical called methane, a simple, compound that has a carbon atom surrounded by four hydrogen atoms. Methane is highly flammable and burns almost completely. There is no ash and very little air pollution.
Natural gas provides one-fifth of all the energy used in the United States. It is especially important in homes, where it supplies nearly half of all the energy used for cooking, heating, and for fueling other types of home appliances. Because natural gas has no odor, gas companies add a chemical to it that smells a little like rotten eggs. The odor makes it easy to smell if there is a gas leak in your house.
The United States has a lot of natural gas, enough to last for at least another 60 years and probably a lot longer. Our neighbor to the north, Canada, also has a lot of gas, and some gas pipelines that begin in Canada run into the United States. The United States is looking for more ways to use gas, largely because it is easy to pipe from one location to another and because it burns very cleanly. More and more, we are using gas in power plants to generate electricity. Factories are using more gas, both as a fuel and as an ingredient for a variety of chemicals.
While natural gas is plentiful, there is still some uncertainty about how much it will cost to get it out of the ground in the future. Like oil, there is "easy" gas that can be produced from underground formations, and there is gas that is not so easy. If we can find better and cheaper ways to find more of the "easy" gas and produce some of the more difficult gas, we can rely increasingly on natural gas in the future. Before we explore ways to do that, let's look back briefly at the history of natural gas.
The History of Natural Gas
The ancient "eternal fires" in the area of present day Iraq that were reported in Plutarch's writings around 100 to 125 AD probably were from natural gas escaping from cracks in the ground and ignited by lightning. In 1821 in Fredonia, New York, William A. Hart drilled a 27-foot deep well in an effort to get a larger flow of gas from a surface seepage of natural gas. This was the first well intentionally drilled to obtain natural gas.
For most of the 1800s, natural gas was used almost exclusively as a fuel for lamps. Because there were no pipelines to bring gas into individual homes, most of the gas went to light city streets. After the 1890s, however, many cities began converting their street lamps to electricity. Gas producers began looking for new markets for their product. In 1855, Robert Bunsen invented a burner that mixed air with natural gas. The "Bunsen burner" showed how gas could be used to provide heat for cooking and warming buildings. It took the construction of pipelines to bring natural gas to new markets. Although one of the first lengthy pipelines was built in 1891,it was 120 miles long and carried gas from fields in central Indiana to Chicago - there were very few pipelines built until after World War II in the 1940s.
Improvements in metals, welding techniques and pipe making during the War made pipeline construction more economically attractive. After World War II, the nation began building its pipeline network. Throughout the 1950s and 1960s, thousands of miles of pipeline were constructed throughout the United States. Today, the U.S. pipeline network, laid end-to-end, would stretch to the moon and back twice.
How Natural Gas is produced
Natural gas is, in many ways, the ideal fossil fuel. It is clean, easy to transport, and convenient to use. Industrial users use almost half of the gas produced in the U.S. A large portion is also used in homes for heating, lighting, and cooking. However, there are limits on how much natural gas we can find and get out of the ground with today's technologies.
Researchers are continuing to study about how natural gas was formed and where it has collected within the earth's crust. They have found that gas is not only found in pockets by itself but in many cases, with oil. Often, both oil and gas flow to the surface from the same underground formation.
Like oil production, some natural gas flows freely to wells because the natural pressure of the underground reservoir forces the gas through the reservoir rocks. These types of gas wells require only a ""Christmas tree", or a series of pipes and valves on the surface, to control the flow of gas. Only a small number of these free-flowing gas formations still exist in many U.S. gas fields, however. Almost always, some type of pumping system will be required to extract the gas present in the underground formation.
One of the most common is the "horse head" pump (see photo) which rocks up and down to lift a rod in and out of a well bore, bringing gas and oil to the surface. Often, the flow of gas through a reservoir can be improved by creating tiny cracks in the rock, called "fractures", that serve as open pathways for the gas to flow. In a technique called "hydraulic fracturing", drillers force high-pressure fluids (like water) into a formation to crack the rock. A "propping agent", like sand or tiny glass beads, is added to the fluid to prop open the fractures when the pressure is decreased.
Natural gas can be found in a variety of different underground formations, including:
1. shale formations,
2. sandstone beds,
3. coal seams, and
4. deep, salt water aquifers (underground ponds of water).
Some of these formations are more difficult and more expensive to produce than others, but they hold the potential for vastly increasing the nation's available gas supply. The Department of Energy is funding research into how to obtain and use gas from these sources. Some of the work has been in Devonian shales, which are rock formations of organic rich clay where gas has been trapped. Dating back nearly 350 million years (to the Devonian Period), these black or brownish shales were formed from sediments deposited in the basins of inland seas during the erosion that formed the Appalachian Mountains.
Devonian shale actually gave birth to the natural gas industry in this country. The first commercial natural gas well was drilled into a shale formation in New York. It produced only a few thousand cubic feet of gas per day for 35 years, but it heralded a new energy source. Other sources of unconventional gas include "tight sand lenses". These deposits are called "tight" because the holes that hold the gas in the sandstone are very small. It is hard for the gas to flow through these tiny spaces. To get the gas out, drillers must first crack the dense rock structure to create ribbon-thin passageways through which the gas can flow.
So the next time, you see the blue flame on top of the kitchen stove, remember that the natural gas that is being burned likely came from an underground rock formation hundreds if not thousands of miles away.