A pump jack is a device used in the petroleum industry to extract crude oil from a oil well where there is not high enough pressure in the well to force the oil to the surface. These pump jacks physically extract the oil for use. Pump jacks and oil derricks are commonly confused, but are not the same.
Pump jacks operate by creating something known as artificial lift. This process of creating artificial lift simply increases the pressure within an oil well to pull oil to the surface. It is common for there to be insufficient pressure in the reservoir to push oil to the surface, and thus this artificial lift is used to increase production from a well. Sometimes artificial lift is required from the very beginning, whereas other times production of a well decreases over time as the pressure drops and artificial lift is needed to boost production. The beam pumping method utilized by pump jacks is the most common method for creating artificial lift.
Pump jacks operate on the same basic principle of some hand pumped water wells that some people are familiar with. Pump jacks are classified as a type of artificial lift pump system, and are the most common type of artificial lift system. This type of system uses equipment above and below ground to push oil to the surface.
These devices are composed of a long, heavy beam that is moved by some external power source. This source causes the end of the beam to rise and fall. At the end of this heavy beam are a series of rods known as sucker rods. As the beam rises and falls, the series of sucker rods dips into and out of the well. These rods are connected to a sucker rod pump, which is installed near the bottom of the well. As the system moves up and rod, the sucker rod pump works somewhat like a piston - increasing pressure within the well - and lifts the oil from the reservoir to the surface. The other end of the beam is connected to a pulley system which provides the continuous movement of the pump jack.