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Roger Weller, geology instructor

fossil fuels
by Zachary Townsley
Physical Geology
Fall 2017

                                                                                 Fossil Fuels


What are fossil fuels? 
    Ever thought what powers your car or where the heat comes from in your house?   This is all possible thanks to fossil fuels.  Fossil fuels are defined as fossil energy sources, including oil, coal and natural gas, are non-renewable resources that formed when prehistoric plants and animals died and were gradually buried by layers of rock.  Over millions of years, different types of fossil fuels formed -- depending on what combination of organic matter was present, how long it was buried and what temperature and pressure conditions.

What are fossil fuels used for?  
     Fossil fuels are used for a wide variety of uses such as coal is used to burn in order to create electricity to power your house schools, and business.  Natural gas to burn to heat your house and to cook with.  Oil that is turned into gas to run your car and to transport food and goods.

How do fossil fuels form?
    Creating such a needed resource takes millions of years.  Fossil fuels are formed when dead, buried, and decomposing organisms are compressed under extreme pressure and heat for millions of years.  Oil and natural gas are typically formed from decomposing phytoplankton and zooplankton below the ocean floor and lake beds.  Coal is typically formed by decomposing terrestrial (land dwelling) plants.  During this process, organic material is first pressed into a waxy material known as kerogen (found in oil shale), then into liquid and gaseous hydrocarbons in a process known as catagenesis.

Above is an illustration on the process of how fossil fuels were formed from decaying material.

How are fossil fuels mined?  
     There are many different process when mining for resources.  The basic idea is to remove or extract the material out of the ground without destroying it or the environment.

Mining for Coal
      There are two main types of coal mining. Surface mining and underground mining.  The process that is used depends on the are and if the coal seam is close to the surface or further in the ground.  Underground mining is the most common do to the amount of coal that has already been removed.  For surface mining the overlaying rock is removed by explosives then the rock is removed with shovels and the coal is exposed.  From here it is drilled and fractured and put into strips to be transported back to be processed.

What is oil?
     Another very important fossil fuel is oil which is used for gasoline diesel and as a lubricant.  Oil comes from the remains of tiny plants and animals (plankton) that died in ancient seas between 10 million and 600 million years ago.  After the organisms died, they sank into the sand and mud at the bottom of the sea.

     Over the years, the organisms decayed in the sedimentary layers.  In these layers, there was little or no oxygen present.  So, microorganisms broke the remains into carbon-rich compounds that formed organic layers.  The organic material mixed with the sediments, forming fine-grained shale, or source rock.  As new sedimentary layers were deposited, they exerted intense pressure and heat on the source rock. The heat and pressure distilled the organic material into crude oil and natural gas. The oil flowed from the source rock and accumulated in thicker, more porous limestone or sandstone, called reservoir rock.  Movements in the Earth trapped the oil and natural gas in the reservoir rocks between layers of impermeable rock, or cap rock, such as granite or marble.

How Do geologist find oil?
     There are three different ways to find oil.  The first way is to interpret geological surfaces and soil types.  They will take ground samples wherever they think oil could be residing.  Another method is to use sensitive  
gravity meters to measure tiny changes in the Earths gravitational field that could indicate flowing oil, as well as sensitive magnetometers to measure tiny changes in the Earth's magnetic field caused by flowing oil.  They can detect the smell of hydrocarbons using sensitive electronic noses called sniffers.  Finally, and most commonly, they use seismology, creating shock waves that pass through hidden rock layers and interpreting the waves that are reflected to the surface.
The picture above shows how hydrophones send waves down to the ocean floor and reflex back up to the surface allowing the geologist to interpret the data.

How do they mine for oil?  
     Since most oil is located in the ocean, oil rigs, which are floating on the water. are built to drill into the ground and pump the oil out of the ground and bring it to the surface.  The drill is inserted into the ground and is surrounded by a concert cone to prevent the oil from flowing out into the ocean and prevents the hole from collapsing in on its self.

This picture is illustrating the process of drilling into the ocean floor to extract the oil. While the concert pipe surrounds it. 

What is natural gas?
     Natural gas is natural occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes.

How is natural gas formed? 
     Just like oil natural gas is formed from decay plants and animals that have died and decomposed over 550 million years ago and has now mixed with mud and other sediments.

How is it mined?  
     The process for mining natural gas is similar to that of oil.  A drill rig is placed above the location and the drill is inserted into the ground.  Once the natural gas deposit has been reached the temperature in the deposit hole is lowered so that the gas will turn into a liquid this is achieved by pumping liquid nitrogen into the hole.  Once the gas has been converted into liquid it can now be pumped up to holding tanks.

In conclusion. fossil fuels effect everyone’s life and transportation.  Fossil fuels,without these non-recordable resources, we would not be where we are today.