How drilling takes place?

Drilling a well to penetrate the subsurface sounds easy enough when in fact it is anything but. Drilling for oil is a monumental task that involves careful planning, huge financing and accurate execution. Having said that, sometimes it can become a bit too overwhelming to imagine what actually goes on in the subsurface during drilling. For this very purpose i would like to share this short but effective animation video, demonstrating a couple of the key aspects of drilling; namely the role of the drilling fluid and the rotation of the drill bit cones which move independent of each other as well as being independent of rotation of the drill string.