Understanding Kick and Influx in Drilling and Completion Operations

In the realm of well control, encompassing both drilling and completion operations, the terms kick and influx hold significant importance. This article aims to explain the distinctions between these two terms, offering insights into their unique characteristics within the context of well control.

What is Kick?

Kick : A kick is the unwanted influx of formation fluid into the wellbore, typically occurring when the pressure exerted by the column of drilling fluid is insufficient to overcome the pressure from fluids in a permeable formation. Unintentional kicks, such as drilling into abnormally pressured formations or inadequately maintaining hole fullness during tripping, constitute the majority of kick incidents. Vigilance throughout rig operations is crucial to prevent kicks, especially considering historical industry data indicating a higher likelihood of kicks during rig operations.

While intentional flows of formation fluids are desirable in certain situations, such as during well production or drill stem testing, unintentional kicks during completion, workover, or drilling operations pose a significant threat to well control if immediate action is not taken.

What is Influx?

 Influx: An influx is the entry of formation fluid into the wellbore, with varying potential to reduce hydrostatic pressure below formation pressure. Regardless of its impact on pressure, an influx signals that the exposed, porous, and permeable formation’s pressure has surpassed the adjacent wellbore pressure at some point. Failure to promptly recognize an influx, especially one involving gas, can lead to further reductions in hydrostatic pressure, ultimately risking the loss of well control.

Wells experience kicks when the reservoir pressure of an exposed, permeable formation exceeds the wellbore pressure at that depth. Several factors contribute to this underbalanced condition, including:

  • Low-density drilling fluid.
  • Abnormal formation pressure.
  • Swabbing.
  • Insufficient hole fullness during trips.
  • Lost circulation.


Cormack, D. (2007). An introduction to well control calculations for drilling operations. 1st ed. Texas: Springer.
Crumpton, H. (2010). Well Control for Completions and Interventions. 1st ed. Texas: Gulf Publishing.
Grace, R. (2003). Blowout and well control handbook [recurso electrónico]. 1st ed. Paises Bajos: Gulf Professional Pub.

Share the joy
Tagged , . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.