Page 287 - Drilling Technology in Nontechnical Language

278 Drilling Technology in Nontechnical Language Second Edition

simply circulate out the influx. Pump pressure is held constant at PC by
1

manipulating the choke for the whole of the first circulation. Once the

influx is out, if the pumps are stopped and the choke is closed, the pressure
on both drillpipe and annulus should be the same and equal to the original
shut-in drillpipe pressure.
For the second circulation, the only calculation required is the density
of the kill mud, ρ . During phase 1, the choke pressure is held constant at
2

a pressure equal to the shut-in pressure at the end of the first circulation.
Pump pressure will decrease during phase 1 as heavy mud replaces light
mud in the drillpipe. Once phase 1 is complete, attention is switched to
the pump pressure gauge, and pump pressure is now held constant by
manipulating the choke until heavy mud returns are seen from the annulus.
If a balanced kill is used, the phase 1 graph is a bit more complicated

to follow, as it is not a straight line. This is illustrated in figure 11–13.
However, as phase 1 proceeds, the pump pressure will tend to follow the
line fairly closely with only small adjustments to the choke.

In a horizontal well, the cause of the kick is unlikely to be drilling into
an overpressured zone. It may be a swabbed kick or some other cause. In
this case, heavy mud is not required; it is just necessary to circulate out the

influx while holding pressure over the chokes.

Fig. 11–13. Deviated well kill phase 1 graph

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