Swabbing occurs in both conventional (vertical) and unconventional fields (horizontal).
Unconventional wells typically produce naturally for a comparatively short period and as reservoir pressures drop, artificial lift methods must be employed to lift the fluids to surface. When the weight of produced fluids exceeds the wells natural, (pressure) or artificial lift systems ability to lift them, production stops and the need to swab off the fluid in the well exists.
The primary downhole tool string for swabbing consists of weight bar and a swab mandrel with rubber, or poly type swab cups suited for the tubing size, type and the fluid to be removed. The swab truck has a boom, winch and pressure control equipment. Once rigged up and downhole, the swab truck operator, using the winch and cable begins to raise the tool string and the swab cups lift the fluid to surface. Operators swab the produced fluids into the flow line, or into a swab tank. Once enough hydrostatic fluid weight is removed from the wellbore production will resume.