Page 38 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

open/close valve can be inserted in the tubing. A plunger catcher at the top
opens the valve and can hold the plunger, while another mechanism
downhole will close the valve.

The cycle starts with
the plunger falling into
the well with its valve
open. Condensed gas
and oil can pass
though the plunger
until it reaches
bottom. There the
valve is closed, now
with a volume of oil,
condensate or water
on top. Gas pressure
starts to accumulate
under the plunger and
after a time pushes
the plunger upwards,
with liquid on top,
which eventually flows
out of the wellhead
discharge.

When the plunger
reaches the wellhead
plunger catcher, the
valve opens and allows gas to flow freely for some time while new liquid
collects at the bottom. After a preset time the catcher will release the plunger
and the cycle repeats.

3.7 Well workover, intervention and
stimulation.

After operating for some time, a well may become less productive or faulty
due to residue build up, sand erosion, corrosion or reservoir clogging.

Well workover is the process of performing major maintenance on an oil or
gas well. This might include replacement of the tubing, a cleanup or new
completions, new perforations and various other maintenance works such as
the installation of gas lift mandrels, new packing etc.

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