Page 59 - Practical Well Planning and Drilling Manual

Section 1 revised 11/00/bc 1/17/01 2:55 PM Page 35

1.3.6
Precompletion and Completion Design [ ]

Squeezing cement
Abandonment/fishing
Completion tubing should be checked under the different operat-
ing conditions for possible buckling. If an anchor seal assembly or
a tubing run packer is used, refer to Section 1.4.14, “Calculating
for Buckling (Nb)” to calculate whether the tubing will buckle just
above the packer. Include in the axial force calculations any
planned setdown weight that will be left on the seal assembly.

All of the relevant operating conditions listed in the previous point
should be considered. In addition, yield strength reduction due to
increased temperature may be significant. Refer to Section 1.4.9.
“Factors Affecting Pipe Yield Strengths.” If an anchor seal assembly
is not run but the completion incorporates a sealing assembly that
lands in a packer, then when calculating the axial force the effect of
pump out of the seal assembly has to be added. This force is the
product of

(internal pressure - external pressure)x(packer sealbore area), or

Force = ∆ P×.7854 d 2

where ∆P is the pressure differential (positive if internal pressure
is greater than external) and d is the packer bore diameter.
If the tubing is set down by greater than the pump out force, or if
an anchor seal assembly is run, use the planned setdown force
instead of the pump out force when calculating the buckling force.
Buckling will put high stress on the completion and may make it
hard or impossible to run wireline tools (depending on the buck-
ling “wavelength”).
Completion components should be checked for compatibility with
the produced fluids, treatment chemicals, and packer fluid. The
presence of H2S, CO2, chlorides, water, etc., will affect the materi-
al used and may dictate that alloy steels be used. Refer to Section
1.4.19, “Material Grades.”

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