An oil well works because it is drilled from the surface of the land down an oil reservoir. Oil can also be produced from an oil saturated permeable rock.

There are really just a few key factors of an oil or gas well. Oil or gas bearing formation, the hole, several lengths of steel pipes, cement to hold the pipe in place and the surface well-head connection are all essential parts to a working well You can find more information here: http://www.geomore.com/Completed%20Well....