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operate underground, down in the well. The surface-pumping unit,
which drives the underground pump, consists of a prime mover
(usually an electric motor) and, normally, a beam fixed to a pivotal
post. The post is called a Sampson post, and the beam is normally
called a walking beam.
This system allows the beam to rock back and forth,
moving the downhole components up and down in the process.
The entire surface system is run by a prime mover, V-belt drives,
and a gearbox with a crank mechanism on it. When this type of
system is used, it is usually called a beam-pump installation.
However, other types of surface-pumping units can be used,
including hydraulically actuated units (with and without some type
of counterbalancing system), or even tall-tower systems that use a
chain or belt to allow long strokes and slow pumping speeds. The
more-generic name of sucker-rod lift, or sucker-rod pumping,
should be used to refer to all types of reciprocating rod-lift
methods [13].
Linked rods attached to an underground pump are
connected to the surface unit. The linked rods are normally called
sucker rods and are usually long steel rods, from 5/8 to more than
1 or 1 1/4 in. in diameter. The steel rods are normally screwed
together in 25- or 30-ft lengths; however, rods could be welded
into one piece that would become a continuous length from the
surface to the downhole pump. The steel sucker rods typically fit
inside the tubing and are stroked up and down by the surface-
pumping unit. This activates the downhole, positive-displacement
pump at the bottom of the well. Each time the rods and pumps are
stroked, a volume of produced fluid is lifted through the sucker-
rod tubing annulus and discharged at the surface.
Many factors must be considered when determining the
most appropriate lift system for a particular well. Artificial lift
selection methods presents a discussion of the normally available
artificial-lift techniques, their advantages and disadvantages, and
the selection of a method for a well installation.
Sucker-rod pumping systems should be considered for new,
lower volume stripper wells, because they have proved to be cost
effective over time. Operating personnel usually are familiar with

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