Page 47 - Practical Well Planning and Drilling Manual

Section 1 revised 11/00/bc 1/17/01 2:55 PM Page 23

1.3.1
Precompletion and Completion Design [ ]

Permanent packers set in the well will work over a range of casing
sizes and weights. The correct packer must therefore be used. If the
packer is only available to fit a certain casing’s inside diameter (ID),
it may affect the choice of casing. Where heavier wall casing
(smaller ID) is run higher up, the packer will have to clear through
the smaller ID when run and there must be sufficient clearance.
Special drift casing could also be used.
If the completion is to sting into the liner polished bore receptacle
(PBR) then the liner must incorporate a PBR and generally will
require a polishing mill to be run before the completion. This could
be combined with a bit and scraper run.
It is essential that the liner lap seals. Liner hangers can incorporate
integral packers, which are set after cementing; this may save time
compared to running a tieback packer and can isolate the forma-
tion from well pressures while the cement is still fluid (e.g., when
reversing out excess cement).

Other preparatory work that may affect the well design apart from
the casings includes:

Completion fluid characteristics may be dictated by the type of per-
forations, reservoir physical characteristics, and reservoir fluids
chemistry.

Running the completion. The following circumstances may affect
the well design:

Tubing accessories outside diameters (ODs) (such as SSSV nip-
ples, side pocket mandrels, packers, etc.) may dictate the possible
range of casing IDs. In some cases a tapered casing string is
required; for instance if a 7 in completion is run in 9 5 /8 in casing,
the SSSV nipple may be too large for the 9 5 /8 in casing ID. It may
be possible to run 10 3 /4 in casing higher up, swaged down to 9 5 /8
in below the SSSV depth. Of course this introduces further com-
plications for running and cementing.
If a dual completion is run, the sizes of tubings, collars, and acces-
sories must be carefully checked to ensure that sufficient clearance
exists inside the production casings. Remember that the strings

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