Page 253 - Well Control for Completions and Interventions

Well Kill, Kick Detection, and Well Shut-In 247

• Displacement of a heavy fluid with a lighter fluid to provide an under-
balanced cushion prior to perforating.
• The opening of a communication port or sleeve above the production
packer in a completed well where kill weight fluid has been left in the
annulus and hydrocarbons remain in the tubing.

7.3.5 Opening the circulation path
In wells completed with a packer, it will be necessary to create a flow
path between the annulus and tubing to allow circulation. Some comple-
tions have equipment that is designed to allow communication between
tubing and annulus, usually a sliding sleeve, or side pocket mandrel. a
When using a sliding sleeve, it is normally opened using a slickline
deployed mechanical shifting tool. Sliding sleeves in old wells are usually
very difficult to open, and it may be less time consuming to simply run a
tubing punch.
Side pocket mandrels are occasionally placed in a well specifically to pro-
vide a communication path between tubing and annulus. They are normally
run with a dummy (blank) valve pre-installed. When tubing/annulus com-
munication is needed, slickline is used to recover the dummy valve, leaving
ports in the side pocket mandrel open. Side pocket mandrels are commonly
found in gas lift wells, with most of these wells requiring more than one
mandrel. The bottom mandrel is normally positioned a short distance above
the packer, and is fitted with a retrievable orifice valve. The orifice valve
allows fluid to flow from the annulus to the tubing, but flow in the opposite
direction should be prevented by non-return valves. All other mandrels in
the well are fitted with retrievable unloading valves. These allow annulus to
tubing communication when open, but close-in response to a pre-
determined casing pressure. Like the orifice valve, the unloading valves have
non-return valves to prevent fluid flow from tubing to annulus. To effec-
tively kill a well, fluid must be circulated through the bottom mandrel, the
one closest to the packer. To do this, the unloading valves in the higher
mandrels must be replaced with blank valves that isolate the circulating
ports. Failure to do so would result in fluid taking the path of least resistance
and simply circulating through the upper side pocket mandrel. It is also best
to pull the orifice valve in the bottom side pocket mandrel, since leaving it
in place would restrict circulation rates. It would also prevent changing the
a
The sliding sleeve and side pocket mandrel are described and illustrated in Chapter 3,
Completion Equipment.