They are sought after because they contain stored energy, and when burned, fossil fuels power machinery and provide transportation, as well as the electricity essential to modern-day life. They also contain essential ingredients used within the chemical industry. Every crude oil deposit has a unique composition and proportion of these hydrocarbons. Based upon this chemical composition, crude oil can have a range of densities from thick and viscous to light and fluid. It is designated as either sweet or sour depending upon residual amounts of sulfur and can range from a transparent golden yellow to a deep black.
In order to be used within industry and for transportation the crude oil must be separated into its individual hydrocarbon-based fuels and lubricants. It became trapped if it reached impermeable rock. Oil companies can drill down through the impermeable rocks to get it out. They are then able to turn it into products we can use, such as petrol and diesel. Formation of fossil fuels Crude oil, coal and gas are fossil fuels.
Related Stories. However, a new study reveals that the climate For every megawatt of electricity produced using natural gas instead of A generator-level model suggests that Now, a group of scientists has found a solution -- by characterizing a hybrid separation membrane for Have We Detected Dark Energy? Scientists Say It's a Possibility. Petroleum slowly seeps out toward the surface, where there is lower pressure. It continues this movement from high to low pressure until it encounters a layer of rock that is impermeable.
The petroleum then collects in reservoirs, which can be several hundred meters below the surface of the Earth. Oil can also be contained by stratigraphic traps.
Different strata, or layers of rock, can have different amounts of porosity. Crude oil migrates easily through a layer of sandstone, for instance, but would be trapped beneath a layer of shale. Geologists, chemists, and engineers look for geological structures that typically trap petroleum. During the process, a small explosion is set off.
Sound waves travel underground, bounce off of the different types of rock, and return to the surface. Sensors on the ground interpret the returning sound waves to determine the underground geological layout and possibility of a petroleum reservoir. The amount of petroleum in a reservoir is measured in barrels or tons.
An oil barrel is about 42 gallons. This measurement is usually used by oil producers in the United States. Oil producers in Europe and Asia tend to measure in metric tons. There are about 6 to 8 barrels of oil in a metric ton. The conversion is imprecise because different varieties of oil weigh different amounts, depending on the amount of impurities. Crude oil is frequently found in reservoirs along with natural gas. In the past, natural gas was either burned or allowed to escape into the atmosphere.
Now, technology has been developed to capture the natural gas and either reinject it into the well or compress it into liquid natural gas LNG. LNG is easily transportable and has versatile uses. Extracting Petroleum In some places, petroleum bubbles to the surface of the Earth.
In parts of Saudi Arabia and Iraq, for instance, porous rock allows oil to seep to the surface in small ponds. However, most oil is trapped in underground oil reservoirs.
The total amount of petroleum in a reservoir is called oil-in-place. These petroleum liquids may be too difficult, dangerous, or expensive to drill. Drilling can either be developmental, exploratory, or directional. Drilling in an area where oil reserves have already been found is called developmental drilling. Prudhoe Bay, Alaska, has the largest oil reserves in the United States. Developmental drilling in Prudhoe Bay includes new wells and expanding extraction technology.
Drilling where there are no known reserves is called exploratory drilling. McCarthy struck oil 38 times in the s, earning millions of dollars. Directional drilling involves drilling vertically to a known source of oil, then veering the drill bit at an angle to access additional resources. Accusations of directional drilling led to the first Gulf War in Iraq accused Kuwait of using directional drilling techniques to extract oil from Iraqi oil reservoirs near the Kuwaiti border.
Iraq subsequently invaded Kuwait, an act which drew international attention and intervention. After the war, the border between Iraq and Kuwait was redrawn, with the reservoirs now belonging to Kuwait. Oil Rigs On land, oil can be drilled with an apparatus called an oil rig or drilling rig.
Offshore, oil is drilled from an oil platform. Primary Production Most modern wells use an air rotary drilling rig, which can operate 24 hours a day. In this process, engines power a drill bit. A drill bit is a cutting tool used to create a circular hole. The drill bits used in air rotary drilling rigs are hollow steel, with tungsten rods used to cut the rock.
Petroleum drill bits can be 36 centimeters 14 inches in diameter. As the drill bit rotates and cuts through the earth, small pieces of rock are chipped off. A powerful flow of air is pumped down the center of the hollow drill, and comes out through the bottom of the drill bit.
The air then rushes back toward the surface, carrying with it tiny chunks of rock. Geologists on site can study these pieces of pulverized rock to determine the different rock strata the drill encounters. When the drill hits oil, some of the oil naturally rises from the ground, moving from an area of high pressure to low pressure.
It is also one of the most dangerous, and a piece of equipment called a blowout preventer redistributes pressure to stop such a gusher. Pumps are used to extract oil. Most oil rigs have two sets of pumps: mud pumps and extraction pumps. Mud pumps circulate drilling fluid. The petroleum industry uses a wide variety of extraction pumps. Which pump to use depends on the geography, quality, and position of the oil reservoir.
Submersible pumps, for example, are submerged directly into the fluid. A gas pump, also called a bubble pump, uses compressed air to force the petroleum to the surface or well. One of the most familiar types of extraction pumps is the pumpjack , the upper part of a piston pump. A crank moves the large, hammer-shaped pumpjack up and down. Far below the surface, the motion of the pumpjack moves a hollow piston up and down, constantly carrying petroleum back to the surface or well. Successful drilling sites can produce oil for about 30 years, although some produce for many more decades.
Other methods are necessary to extract this petroleum, a process called secondary recovery. Vacuuming the extra oil out was a method used in the s and early 20th century, but it captured only thinner oil components, and left behind great stores of heavy oil.
Water flooding was discovered by accident. In the s, oil producers in Pennsylvania noticed that abandoned oil wells were accumulating rainwater and groundwater. The weight of the water in the boreholes forced oil out of the reservoirs and into nearby wells, increasing their production.
Oil producers soon began intentionally flooding wells as a way to extract more oil. The most prevalent secondary recovery method today is gas drive. During this process, a well is intentionally drilled deeper than the oil reservoir. The deeper well hits a natural gas reservoir, and the high-pressure gas rises, forcing the oil out of its reservoir. Oil Platforms Drilling offshore is much more expensive than drilling onshore. It usually uses the same drilling techniques as onshore, but requires a massive structure that can sustain the tremendous strength of ocean waves in stormy seas.
Offshore drilling platforms are some of the largest manmade structures in the world. They often include housing accommodations for people who work on the platform, as well as docking facilities and a helicopter landing pad to transport workers. The platform can either be tethered to the ocean floor and float, or can be a rigid structure that is fixed to the bottom of the ocean, sea, or lake with concrete or steel legs. More than 70 people work on the platform, in three-week shifts. The platform is meters feet tall and is anchored to the ocean floor.
About , tons of solid ballast were added to give it additional stability. The platform can store up to 1. In total, Hibernia weighs 1. However, the platform is still vulnerable to the crushing weight and strength of icebergs. Its edges are serrated and sharp to withstand the impact of sea ice or icebergs. Oil platforms can cause enormous environmental disasters. Problems with the drilling equipment can cause the oil to explode out of the well and into the ocean. Repairing the well hundreds of meters below the ocean is extremely difficult, expensive, and slow.
Millions of barrels of oil can spill into the ocean before the well is plugged. When oil spills in the ocean, it floats on the water and wreaks havoc on the animal population. One of its most devastating effects is on birds. Oil destroys the waterproofing abilities of feathers, and birds are not insulated against the cold ocean water.
Thousands can die of hypothermia. Fish and marine mammals, too, are threatened by oil spills. The dark shadows cast by oil spills can look like food.
A massive oil platform in the Gulf of Mexico, the Deepwater Horizon , exploded in This was the largest accidental marine oil spill in history.
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