TECH TUESDAY: How do we get our oil?
Protests against a new oil pipeline in North Dakota have garnered much attention in recent days, with hundreds of people making their way to the junction of the Cannonball and Missouri Rivers.
These protests stem from the planned construction of a 1,172-mile pipeline running through North Dakota, near a Sioux reservation and cross under the Missouri River. Some fear it will pollute drinking water, while others say it will bring oil to refineries more easily.
Oil is formed over millions of years. Dead organisms fell to the bottom of the seas and were eventually covered by mud, according to the website for the British Broadcasting Company (BBC).
Throughout time, the mud becomes rock and becomes hotter from other rocks in the area. This combination of heat and pressure on the dead organism eventually turns it into a liquid called "crude oil," according to the site.
This crude oil is covered by a layer of rock and cannot pass through it, meaning it cannot leak out into the water. Crude oil is what oil companies take out and refine for later use, according to the site.
Initially, people searching for oil would guess what rocks it might be under and simply began to dig down, hoping for the best. The wells made in this process were called "wildcat wells," according to the website for the New Mexico Oil and Gas Association (NMOGA).
Now, geologists use a variety of methods to find oil. Observing rocks to find the optimal conditions for oil formation enables them to narrow down potential oil locations. This can be aided through the use of satellite imaging, according to howstuffworks.com.
Additional tools can also be used, such as magnetometers or sensitive gravity meters. Magnetometers measure changes in the Earth's magnetic field, which can be attributed to oil flow. Gravity meters measure changes in the Earth's gravitational field to do the same, according to the site.
Machines called "sniffers" detect the presence of hydrocarbons, leading geologists directly to the oil, according to the site.
Most commonly, seismology is used. Through this, geologists send sound waves to the rock and measure the wave returned to them, according to the site.
The rate at which sound waves pass through solids, liquids and gasses is very different. Geologists can determine what substance is under a rock by measuring the sound wave that is reflected back to them, according to the NMOGA website.
Geologists cast out extremely sensitive microphones and create some sort of shockwave at the rock surface. The microphones record the sound waves reflected back from the many layers of rock, according to the site.
Sound waves travel fastest through solids and slowest through gasses, so measuring how quickly the sound wave was reflected would identify the object underneath the rock, according to the site.
Shock waves can be produced through the use of a compressed-air gun, which shoots air into the water, or thumper trucks, which slam plates against the ground. Explosives can also be used, detonated underground or thrown into the water, according to howstuffworks.com.
Once the oil-extraction site is selected, scientists determine the boundaries of the site and check for any potential environmental impacts. Then, before land can be drilled, oil companies obtain permission and leases to ensure control of the land, according to the site.
After all of these procedures, the company begins to prepare the land for drilling. It is leveled, access roads are built, water sources are identified and a pit is dug to dispose of anything dug up during the drilling process, according to the site.
Finally, a pit called a "cellar" is dug around the area where the drill will go, giving ample space for any additional accessories and workers. The main hole is made in the middle of the cellar with a small truck, and when it is completed the main rig is brought in, according to the site.
Rigs built on the water are built on barges with the help of a helicopter, as there is no foundation for the rig, according to the site.
To actually drill into the ground, a drill bit and drill pipe are placed into the hole, boring into the ground. Mud and rock are circulated out of the drill bit and new pipes are added as the hole gets deeper, until the desired depth is reached, according to the site.
The pipes are cemented into place and drilling resumes until oil is reached. Explosives are sent down the hole to make pores for oil to pass through. Then, more tubes and a structure called a "Christmas tree" are sent down to control the oil flow pressure, according to the site.
The rig is then removed and a pump is added to suck the oil out of the ground, according to the site.
Crude oil is taken and transported through the use of pipelines or tankers to refineries, where it can be purified for consumption in a variety of forms, according to the website for the World Petroleum Council.
Harshel Patel is a School of Arts and Sciences junior majoring in molecular biology and biochemistry. He is the digital editor of The Daily Targum. He can be found on Twitter @harshel_p.