In one sentence, describe what the following article is about:

While entry-level jobs on oil rigs are plentiful and technically don't require any experience, few companies will hire a "green hand" to work on their billion-dollar platforms. In general, oil rig workers only need to be 18 or older, have a high school diploma, and pass a pre-employment drug test. Successful applicants have usually pursued oil rig training independently or bring transferable skills to the job. All workers must meet certain minimum standards and certifications to work on an oil rig. Since many oil rigs are in international waters or even in foreign countries, it is important to be aware of what documents you'll need if you must enter another country for the work. Most companies will arrange for a current work visa for people working outside their native country. Oil rig jobs are available in some of the world's most exotic locations, including the coasts of Africa and the waters of Southeast Asia. Workers from other regions often get jobs in these areas, but they must complete a full course of immunizations before they will be hired. Some of the most common required vaccinations include Hepatitis A; Hepatitis B; Tetanus; Polio; Measles, Mumps, and Rubella (MMR); Meningitis; Typhoid Fever; Seasonal Influenza; and Yellow Fever. Many trade schools and colleges offer classes on various facets of the oil industry, including oil rig work. Most classes blend coursework with hands-on field experience. Companies often provide training for workers looking to advance their careers in specialized fields. All offshore workers are required to earn an Offshore Survival & Firefighting certificate. Specialized workers like electricians, scaffolders, and welders must hold a state-issued license or certificate in order to work on a rig.
Determine whether you meet the basic requirements. Ask about the work visa requirements. Get the necessary immunizations. Find specialized training courses. Complete the required certifications.