Kick Warning Signs:
What to Look For and How to Respond
A kick that is detected early is manageable. A kick that is missed becomes a blowout. Understanding the indicators — and knowing which ones are definitive versus which ones require a flow check — is one of the most important skills any rig crew can have.
KICK INDICATORS
Eight Indicators Your Well May Be Taking a Kick
Flow Rate Increase
The only way to positively confirm a kick during drilling is to shut down the pump, let the well stabilize, and observe the annulus for flow. Positive flow after the pump is off means formation fluids are entering the wellbore. This is a definitive indicator and requires immediate shut-in.
Pit Volume Increase (Pit Gain)
A flow rate increase usually triggers a flow check first, but if the well is taking a kick, the crew will then observe a pit gain — the drilling fluid being displaced out of the well by incoming formation fluids. Pit gain is one of the most reliable early indicators during normal drilling operations.
Flowing Well With Pumps Off
Any flow from the wellbore when the pumps are shut off is a positive indicator that formation fluids are entering the well. The well must be secured promptly.
Pump Pressure Decrease and Pump Stroke Increase
On older-style pump and power systems, an influx can reduce annular pressure loss near the bit while formation pressure pushes upward — resulting in lower pump pressure and a potential increase in stroke rate. Less common on modern electrical systems, but remains relevant on older equipment.
Improper Hole Fill-Up on Trips
During a trip, the only way to detect a kick is by continuously monitoring and comparing the volume of fluid required to fill the hole against calculated expectations. If the hole is taking less fluid than expected, formation fluids may be entering the wellbore.
String Weight Change (Reduced Hook Load)
An influx of lighter fluid or gas affects buoyancy and increases upward cross-sectional force on the bit — resulting in a reduced hook load. This change in string weight is a warning sign that warrants a flow check.
Drilling Break
A sudden, significant increase in rate of penetration (ROP) indicates the bit has entered a new, more porous formation. That formation may be holding higher-pressure fluids. A positive drilling break requires a flow check before drilling ahead.
Cut Mud Weight (Gas-Cut Mud)
Gas cut mud occurs when small quantities of drilled formation gas are released into the drilling fluid. This reduces fluid density and lowers hydrostatic pressure — which can allow formation fluids to begin entering the wellbore.
SHUT-IN PROCEDURES
Hard Shut-In vs. Soft Shut-In
Hard Shut-In
Closes the BOP first, then opens the flow path to the closed choke manifold. This is the faster method and results in a smaller influx volume. Most widely used method in the industry.
Soft Shut-In
Diverts flow through an open remote choke first, then closes the BOP, then slowly closes the remote choke. Reduces the likelihood of a pressure shock but allows more influx to enter the well. Used in specific situations where wellbore integrity concerns make pressure shock a greater risk.
Key Point
Speed Matters
Whichever method your operation uses, drillers and crews must be empowered to shut the well in immediately using the correct procedure — without waiting for authorization.
HUMAN FACTORS
The Crew Has to Act — Not Wait
A common failure mode in well control incidents is not a lack of knowledge — it is hesitation. Drillers and crews who are not confident in their authority to shut in the well, or who are not certain of the correct procedure, delay action at exactly the moment speed matters most.
