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Mud Hydraulics Optimization 99

With a
Flow
Closed Pipe Fully Open Autofill Diverter

Figure 4.8 Different pipe end conditions.
be determined by any simple method. A split of flow going to the annu-
lus and pipe interior is iteratively calculated. A numerical method must
be used to make sure that the sum of the resulting frictional pressure
drops inside the pipes is equal to that of all the annular sections.

Autofill or Pipe with a Nozzle
The difference between autofill float equipment and a fully open pipe is the
additional pressure drop across the orifices on the autofill float equipment.
Depending on the total flow area of the autofill equipment, the resulting
surge pressure can vary significantly. The actual surge pressure should be
between the pressure of the closed pipe and that of fully open pipe.

Pipe with a Flow Diverter
A new tool, commonly referred to as flow diverter valve or circulation
sub, can be used in conjunction with autofill float equipment. This tool,
which is located on the drill pipe immediately above the liner, has ports
open to the drill pipe annulus. These ports allow the fluid trapped in the