The main aim of any well control program is the prevention of a blowout. Blowout is a condition that allows uncontrolled flow of formation fluid such as gas, oil, water or other fluids into the well or into the atmosphere. Blowout is a direct result of what is known as "kick." A well kick can be defined as the influx of formation fluids into the wellbore.

CAUSES OF KICK

The following are some of the causes of kick;

Failure To Keep The Hole Full.

When the drillstring is removed from the wellbore, the fluid level in the wellbore drops. The volume of the mud that drops is equal to the volume of metal in the drillstring that has been removed from the wellbore. Now, if the hole is not filled up when pulling the drillstring out of the wellbore a kick will probably occur.

Swabbing.

When the drillstring is removed from the wellbore, it is possible that the hydrostatic pressure opposite a given formation may be reduced giving rise to influx of formation fluid into the wellbore known as swabbing. When swabbing occurs, the drillstring should be returned to bottom and any formation fluid which have entered the wellbore should be circulated out before tripping operations are resumed.

Insufficient Mud Weight.

This problem is found in geographical regions where we have abnormally pressured reservoirs and it is common with exploration drilling and can also occur in development wells.
Other causes of kick are; Insufficient Mud Weight, Lost Circulation, Trip Margin Too Low, Drilling Into Another Well, High Drilling Rate. Thanks for reading this post.