ENERGY ENGINEERING

contentsDefinitions Formation of oil and gasThe science of searchingExtraction of oil and gasMoving oil and gasRefiningUseful productsProduction and consumption of oil and gas in Pakistan

ENERGY ENGINEERING(OIL & GAS)

Crude Oil DefinitionA mixture of hydrocarbons that exists in liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. Depending upon the characteristics of the crude stream, it may also include.Small amounts of hydrocarbons that exist in gaseous phase in natural underground reservoirs but are liquid at atmospheric pressure after being recovered from oil well (casing head) gas in lease separators.

Continue2. Small amounts of nonhydrocarbons produced with the oil, such as sulfur and various metals.3. Liquid hydrocarbons produced from tar sands, oil sands and oil shale. Liquids produced at natural gas processing plants are excluded. Crude oil is refined to produce a wide array of petroleum products, including heating oils; gasoline, diesel and jet fuels; lubricants; asphalt; ethane, propane, and butane; and many other products used for their energy or chemical content.

Formation of oil and gasThe petroleum oil that becomes gasoline and many other useful products wouldnt exist without tiny plants, algae and bacteria, which settled to the bottom of the sea as they died millions of years ago.Theres no oxygen under the earths crust, so the organic matter in the sediment changed into a substance scientists call kerogen. And when the temperatures rose to 110 Celsius or higher the kerogen gradually changed into oil. Under hotter conditions it changed into natural gas. The process takes at least a million years.

ContinueCrude oil is a complex mixture of hydrocarbons. In other words, it is made up of hydrogen, carbon and traces of other substances. Its texture varies, but it is generally liquid. Natural gas is mainly made up of the chemical compound methane. It is gaseous, or lighter than air.

ContinueIf the story ended there, oil and gas might never have become the global energy sources they are today. The deposits would be so scattered that we would have almost no chance of extracting them in usable amounts.Even after oil has formed in the rock, pressure continues to rise, squeezing the oil out or upwards through rocks that have more pores, or spaces, within them.

ContinueAll oil moves like this. Some of it eventually reaches the surface and seeps out naturally into land or water, but most of it eventually comes up against a layer of rock that it cant move through. This impermeable rock forms a seal or trap, and slowly, very slowly, the oil builds up. As it does, it forms a reservoir.Reservoirs are rock formations that hold oil, natural gas or both within their pores, like a fossilized sponge. Reservoirs can be massive. Some may be as large as London, Hong Kong or New York

ContinueIf only finding them was as easy as mapping a city. Rocks also move over millions of years. Their formations can be extremely complex. This makes oil and gas reservoirs extremely difficult to find.

The science of searching

Forming an educated guessThere may be no more unexplored frontiers on earth, but deep inside the earth there is plenty that we dont yet know.Oil companies have a range of technologies to help them locate oil and gas reservoirs deep beneath land and sea. But the search remains a complex business. Success is never certain.

Improving the odds

In the early days of oil exploration, oil companies and prospectors really had no idea what they were looking for. They focused their search on areas near seepages, where oil bubbled up naturally in pools. Then they sunk a drill and hoped for the best.The rate of success has improved greatly since those early discoveries, from 10% or less to more like 50%. New technologies developed which may improve the odds.

DrillingDrilling is still the only sure way to find out whether theres oil or gas down there. But drilling is expensive. Each project can cost tens of millions of dollars or more. So before we drill, we do as much planning as possible. And that can take years.

The geologists eyeWe start with what we can see. Both geologists and geophysicists provide crucial insights at this stage in the exploration process. Geologists look at what rocks are made of and the formations they make in the earth. Geophysicists use physical characteristics, such as magnetic and gravitational properties, to guess the type and shape of subsurface rocks.

ContinueAerial photography from aircraft and satellites can be revealing. The same tectonic shifts that formed mountains and other topographical features above the earths surface also shaped the rock formations down below. To the trained eye, these photographs can say a lot about what lies beneath the soil.Aircraft can measure the gravitational pull over an area. Even small gravitational differences can reveal large clues about the density of underlying rocks.

Using sound waves to get the pictureBut the most powerful tool available to us is the acoustic survey. Geophysicists use air guns to fire acoustic pulses down through the rock. The sound waves bounce back like echoes, revealing different layers and depths.This data gives our experts the information they need to map reservoirs and identify whether theyre filled with oil, gas or merely water.

Needless to say, this sort of seismic study is a lot less damaging to the environment than random drilling. But there are still environmental risks to consider. Before we begin a seismic study, we speak with marine biologists where appropriate, and look thoroughly at any environmental issues. For example, work might be delayed so that it doesnt interfere with animals feeding times, breeding periods or migrating seasons18

Safety firstBecause crude oil and natural gas are hot and highly pressurized, we have to take great care to control pressure during the drilling process.Everyone involved in a drilling project undergoes rigorous safety training. Risks are assessed at every step. Increasingly we plan exploration projects remotely, using data instead of site visits, which means fewer employees and contractors are exposed to potential dangers on the actual rig.

Extracting oil and gasAfter weve established that there are large quantities of oil or gas (or both) at a drilling location, this site is known as a field. The next step is to plan and build a production facility, taking environmental, social and logistical factors into account.

Working with local economies Using new technology

Over the decades-long lifespan of most production facilities, chances are new technologies will help us reach deeper and deeper into reservoirs, helping us to extract more of the resources within it.Is the world running out of oil and gas? Not immediately. By most estimates, todays known reserves would last for at least another 40 years at current usage levels. In other words, these estimates dont take new discoveries into account. Meanwhile, new technologies are helping us tap large amounts of oil and gas that were once considered unreachable.

ContinueNot long ago drilling only went in one direction. Down. Now we can drill at any angle, including straight out horizontal. At Wamsutter gas field in Wyoming, USA, horizontal drilling has helped us reach large amounts of natural gas that were previously trapped within rock formations too tight to let the gas flow naturally.

ContinueHere are a few other recent and developing innovations that may help us get more oil and gas from known reservoirs:Fracturing the rocksBy exerting the right level and type of pressure into rocks with tight pores, we can cause fine cracks that stimulate a freer flow of natural gas deposits that would previously have remained trapped there.

ContinueInjecting waterInjecting water into a reservoir to flush out some of the remaining oil trapped in rock pores is a long-established technique. Using water with a lower salt content, a process BP developed and owns, appears to boost oil recovery by as much as 40%.

ContinueInjecting CO2into wellsInjecting natural gas is one way of flushing more oil out of a well. Tests have shown that carbon dioxide, which can be separated from oil and other hydrocarbons during hydrogen power production, may be an effective substitute. Putting this CO2back into the reservoir means it wont be released into the atmosphere, where it would add to the greenhouse gases believed to cause global warming.

Moving oil and gasMost of the worlds known oil and natural gas supplies are a long way away from the places where these resources are the most in demand. Even land-based production facilities may be many kilometers from the closest refinery or distribution terminal.We transport crude oil in two main ways: pipelines and shipping.

Oil transport

ContinueThe choice depends on each projects logistics, economics and location, as well as environmental considerations. Meanwhile, arranging to get large amounts of oil, gas and energy products to all the places where they are needed is a steady and demanding job in itself.

Making fuels and products

In its raw form, crude oil is practically useless. Before it has any real value it must be processed into products like gasoline, motor oils, bitumen and the chemicals that make adhesives, cosmetics and other useful products.We do this processing at our refineries.

How refining works

Transforming crude oil with chemistryRefining is a chemical process. So to really understand how it works we need to know a little basic chemistry.Crude oil is mainly made up of hydrocarbons chains of carbon atoms and hydrogen atoms. The chemical bonds that link these chains together can be broken up and linked in different ways. In fact, the hydrocarbon compound is the most versatile on the chemical charts. It can make an estimated 2.5 million possible combinations. Longer, heavier molecules can be transformed into lighter ones and vice versa.

ContinueBut crude oil is far from pure. It can also contain substances that need to be removed because they would damage an engine or other machinery. In the refinery, we remove sulphur, nitrogen, oxygen, water and other trace substances and then dispose of them safely.

ContinueVaporizing the crude oilThe first step in separating oil into useful products involves heating it to a about 350 Celsius. It is then pumped into a fractioning tower.If you have ever seen an oil refinery from a distance, these are the tall, slender towers that jut up above the horizon. The vaporized oil rises up the tower through trays with holes in them. As the gas cools, its components condense back into several distinct liquids. Lighter liquids like kerosene and naptha, a product used in chemicals processing, collect near the top of the tower, while heavier ones like lubricants and waxes fall through weirs to trays at the bottom.

ContinueDemand for gasoline is high, so we use the flexibility of the hydrocarbon compound to turn some of the heavier components from the fractioning tower into gasoline. Reforming and alkylation are two such processes. Cracking is another. It breaks large hydrocarbon molecules down into smaller ones, making the end product runnier

Fractionating tower

ContinueAfter distillation, gasoline and other engine fuels go on for further processing elsewhere in the refinery. They will leave the refinery by pipeline or truck, having been transformed from a raw material into fuels with marketable octane ratings and specific engine properties.

Refined products

One resource, thousands of usesThe vast majority of the crude oil that goes through one of our refineries leaves it as gasoline. But the range of products we produce is much wider than automotive fuels. In fact, these products touch almost every aspect of modern life.

ContinueHere are a few of our refined products:Liquefied petroleum gas (LPG)Together propane and butane are known as LPG, which is stored in metal containers under pressure as a liquid. It is used for heating and cooking, especially when portability is needed in camping stoves, for example, or on boats.Kerosene (paraffin)Kerosene was the first major product to be refined from crude oil in the late 19th century. At that time it was mainly used for lighting in oil lamps. Today its main use is as jet aircraft fuel.

ContinueLubricating oilsWithout lubricants, the world might not stop spinning but everything on it would grind to a halt. Lubricants have thousands of uses, from fixing squeaky doors to oiling industrial machines and automotive engines.Heavy fuel oilsThese are used in large industrial boilers, in power stations for example, and to raise steam to drive turbines on ships.

ContinueBitumenThis is the heaviest product from the refinery. Essentially its what is left after everything else has been removed from the crude oil. When heated, it can be used in road construction and as a waterproofing material for roofs.WaxesWax is a by-product of the refining process. It is used to make candles, electrical insulation and waterproof coverings for food cartons.

Selling fuels and products

At service stations, ports and airports around the world, fuels and motor oils help keep the world in motion.

References http://www.bp.com/en/global/corporate/about-bp/what-we-do/finding-oil-and-gas/how-oil-and-gas-form.html.http://www.indexmundi.com/energy.aspx?country=pkhttp://www.indexmundi.com/g/g.aspx?c=pk&v=136