Once the equipment is at the site, the rig is set up. Here are the major systems of a land oil rig:
Rig is basicly a Equipment which including necessary machinery like:

•  Power system

•  large diesel engines - burn diesel-fuel oil to provide the main source of power

•  electrical generators - powered by the diesel engines to provide electrical power

•  Mechanical system - driven by electric motors

•  hoisting system - used for lifting heavy loads; consists of a mechanical winch ( drawworks ) with a large steel cable spool, a block-and-tackle pulley and a receiving storage reel for the cable

•  turntable - part of the drilling apparatus

•  Rotating equipment - used for rotary drilling

•  swivel - large handle that holds the weight of the drill string; allows the string to rotate and makes a pressure-tight seal on the hole

•  kelly - four- or six-sided pipe that transfers rotary motion to the turntable and drill string

•  turntable or rotary table - drives the rotating motion using power from electric motors

•  drill string - consists of drill pipe (connected sections of about 30 ft / 10 m) and drill collars (larger diameter, heavier pipe that fits around the drill pipe and places weight on the drill bit)

•  drill bit(s) - end of the drill that actually cuts up the rock; comes in many shapes and materials (tungsten carbide steel, diamond) that are specialized for various drilling tasks and rock formations

•  Casing - large-diameter concrete pipe that lines the drill hole, prevents the hole from collapsing, and allows drilling mud to circulate