The oil industry can be both dirty as well as dangerous. However, it is also an industry, which produces massive profits on a daily basis. Ever since the early 20th century, the world has demanded that more oil be produced.
However, there has always been monopoly by these large oil and gas companies over smaller ones. That being said, many companies have grown to become extremely successful and rich. In fact, some have grown into the largest oil and gas companies in the world. Here is a list of some such companies.