The word petroleum comes from the Greek words “petro” for rock and “oleum” for oil. In its strictest sense, petroleum includes crude oil. By usage, however, petroleum includes both crude oil and natural gas. 
Petroleum naturally occurs from the remains of ancient organisms, such as plants, algae, and bacteria. They were burried by thousand of feet of sand and silt. Over million of years of intense heat and pressure, these organisms transform into carbon-rich yellow-to-black liquid called crude oil. It is then refined into various types products.
Oil & gas industry can be divided into 3:
- Upstream: Chevron, Shell, ExxonMobil
a. Exploration: Done to find where oil reservoirs are located and how big the reservoirs are. Most used methods are seismic surveys, gravitational surveys, and geological mapping.
b. Exploitation: Oil rigs are used to drill holes and extract petroleum to the surface. Nowadays oil can be found at about 1.1 kilometers beneath the surface.
2. Midstream: Plains All American, Kinder Morgan, Trans Canada
Transportation: Both crude oil and natural gas are commonly transported through pipelines
Storage: Crude oil is stored in tankers, while gas is commonly stored in underground inventory under pressure.
3. Downstream: ExxonMobil, Chevron, Shell.
Downstream is mostly about refining. It is done by distillation using heat and pressure to separate thousands of compounds in crude oil. The products are categorized as light, medium, and heavy products.
- Exploration: https://www.youtube.com/watch?v=gIWH5b1_bRY&t=439s
- Exploitation: https://www.youtube.com/watch?v=gIWH5b1_bRY&t=439s
- Transporting: https://www.studentenergy.org/topics/ff-transport
- Storing: https://www.eia.gov/naturalgas/storage/basics/
- Refining: https://www.youtube.com/watch?v=_e0US_VV2AI&t=274s
- Caption (introduction to petroleum): https://www.youtube.com/watch?v=8YHsxXEVB1M
- Exploration: http://setfia.org.au/fishing-industry-calls-for-halt-to-massive-french-seismic-survey/
- Drilling: Hamid, M. and Sulaiman, W. (2010). Drilling Operations. Fundamentals Of Petroleum Engineering, [online] 4, p.22. Available at: http://ocw.utm.my/pluginfile.php/1080/mod_resource/content/0/Chapter_4-OCW.pdf [Accessed 24 Sep. 2018].
- Transporting: https://www.egyptindependent.com/app/uploads/2018/08/Capture-9.png
- Storing: https://www.honiron.com/wp-content/uploads/2017/05/storagetanks.jpg
- Refining: https://upload.wikimedia.org/wikipedia/commons/3/3c/Crude_Oil_Distillation.png
- Chevron: https://www.chevron.com/-/media/shared-media/images/chevron-hallmark-facebook.jpg
- Shell: https://upload.wikimedia.org/wikipedia/en/thumb/e/e8/Shell_logo.svg/1200px-Shell_logo.svg.png
- ExxonMobil: http://1000logos.net/wp-content/uploads/2017/08/ExxonMobil-Logo.png
- Plains All American: https://upload.wikimedia.org/wikipedia/en/4/46/Plains_All_American_Pipeline_logo.png
- Kinder Morgan: https://i0.wp.com/cfnrfm.ca/wp-content/uploads/2018/05/5663201_14909086302298_rId5.png?resize=660%2C254
- Trans Canada: https://shawglobalnews.files.wordpress.com/2016/07/cpt102352617_high1.jpg?quality=70&strip=all&w=650
- Hyne J., Norman. 2012. Nontechnical Guide to Petroleum Geology, Exploration, Drilling, and Production. Tulsa, Oklahoma. PennWell Production.