Kicks occur as a result of formation pressure being greater than mud hydrostatic pressure which causes fluid to flow the formation into the wellbore. The main factors which can lead to this condition can be classified as:
a) Improper hole fill up trips.
b) Swabbing
c) Abnormal formation pressure
d) Insufficient mud density.
e) Lost circulation.
f) Gas cut mud.
More than 50% of the kick occur due to first two of the causes list above.
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