Page 306 - Well Control for Completions and Interventions

Well Kill, Kick Detection, and Well Shut-In 299

4911 3 153
Volume to reach P max 5 5 136:61 bbls
5500
5. The volume of fluid that can be pumped is the original tubing vol-
ume (153 bbls) minus the volume occupied by the compressed gas
(136.61 bbls) 5 16.39 bbls.
6. Pump the calculated volume (16.39 bbls), or until the wellhead pres-
sure reaches the maximum allowable value (5500 psi). Do not exceed
this value even if not all the calculated amount of fluid has been
pumped.
7. Calculate the reduction in hydrostatic head from the volume of fluid
pumped.
volume pumped ðbblsÞ
Height of fluid column ðft:Þ 5 becomes
tubing capacity ðbbl=ftÞ
16:39
5 1100 ft:
0:0149
ð
Hydrosatic pressure 5 kill fluid gradient gas gradientÞ
3 height of fluid column
(0.5827 0.08) 3 1100 5 553 psi.
8. Bleed back to the wellhead pressure at the start of the kill (4911 psi).
Continue to bleed off pressure equal to hydrostatic increase from the
fluid pumped (553 psi). 4911 553 5 4358 psi.
9. Carry out a second lubricate and bleed cycle using the same volume
that was pumped at step 6 (16.39 bbls). The expected pressure
increase is again calculated using Boyle’s law. While not essential, this
calculation assures that the operation is proceeding as planned and
allows an accurate kill graph to be prepared.
Wellhead pressure after pumping 16:31 bbls
4358 3 136:61
5 5 4952 psi:
136:61 2 16:39
10. Bleed off until the wellhead pressure is 553 psi lower than the starting
pressure (before the second stage was performed). 4358 5535 3805 psi.
11. The process of lubricate and bleed is repeated until the tubing is full
of kill weight brine and no gas remains at surface.
The best approach is to create a kill sheet with a table of expected
pressure against volume pumped (Table 7.14). A spreadsheet helps in this
respect. Properly constructed it can be configured to make the calcula-
tions for each step of the lubricate and bleed process (Figure 7.20).