A pulling unit is one of the mechanical oilfield applications used to remove the casing and other tubing apparatuses inside a well bar. It is also used to remove drilling rods inside a wellbore. A pulling unit is called in when a wellbore shows signs of internal damage, such as an obvious leak or a sudden drop in pressure of the drilling fluid at the surface. When a wellbore is displaying production problems that cannot be repaired through more simple means, the unit is charged with physically lifting the casing and any of the drilling equipment that appears to be damaged out of the wellbore to be examined and repaired in a timely manner.
Outside of the oilfield, pulling units are also used in pump pulling applications on land tracts that have well pumping operations, such as at farms that have automated irrigation systems. In this application, the units used to retrieve damaged pumps in farm fields are much smaller than the units used in major oilfield applications. The smaller units can often be operated by one to three people, as opposed to the entire production required for the operation of the oilfield pulling unit.
The construction of a pulling unit apparatus is different among different brands and manufacturers. The construction method may also differ depending on the intended use of the unit. Some units are vertical in form and telescope upward after being connected to the instruments in the wellbore; others are shaped into the form of a wheel, with the pump system attached to the wheel’s axis and cranked around the wheel axle in a winch formation. No matter the shape or form of function, the purpose of the pulling unit is to remove an underground well or pumping system without being required to dig or destroy the surface the system is located under.
Most pulling units are portable so they can be easily moved from pump system to pump system, or from wellbore to wellbore in oilfields. The unit itself is typically mounted onto the back of a heavy duty truck or vehicle, making it easy to move. Most operators are independent contractors who travel to the oilfield or tract of land that they’ve been hired to remove a system from.