Kick & Formation Pressure

 

How to Solve Questions with Confidence and Accuracy

 

After hydrostatic pressure, the next most important calculation topic in the IWCF Drilling Well Control exam is Kick and Formation Pressure calculations. These questions test not only your ability to calculate, but also your understanding of well control logic.

Many candidates know the formulas, yet still lose marks because they:

• Apply the wrong pressure

• Ignore the well condition (static or circulating)

• Focus on numbers instead of well balance

At WellWise Consultancy LLC, we teach candidates to think like IWCF examiners—this blog does exactly that.

 

What Is Formation Pressure? 

Formation pressure is the pressure exerted by fluids in the reservoir.

In IWCF exams, formation pressure is critical because:

• A kick occurs when formation pressure exceeds bottom hole pressure

• All well kill calculations start from formation pressure

📌 IWCF Golden Rule:

You cannot control a well unless you understand formation pressure.

 

When Does IWCF Ask for Formation Pressure?

IWCF usually gives you:

• A shut-in well

• Measured SIDPP or SICP

• Known mud weight and depth

And asks you to determine:

• Formation pressure

• Required mud weight

• Well condition (overbalanced / underbalanced)

 

Formation Pressure Formula (Static Well)

From the IWCF Drilling Formula Sheet (API units):

Formation Pressure=Hydrostatic Pressure+SIDPP

Where:

• Hydrostatic Pressure = MW × 0.052 × TVD

• SIDPP = Shut-In Drill Pipe Pressure

📌 Exam Tip:Use SIDPP, not SICP, for formation pressure unless the question specifically states otherwise.

 

Exam Scenario 1 – Formation Pressure Calculation

Given:

• Mud Weight = 10.0 ppg

• TVD = 9,000 ft

• SIDPP = 450 psi

Step 1: Calculate Hydrostatic Pressure

10.0×0.052×9000=4,680 psi

Step 2: Calculate Formation Pressure

4,680+450=5,130 psi

✅ Correct Answer: Formation Pressure = 5,130 psi

 

Why IWCF Uses SIDPP (Not SICP)

• SIDPP reflects pressure acting directly at the bit

• It is unaffected by annular geometry

• It provides a true representation of formation pressure

📌 IWCF Exam Trap:If you automatically use SICP, your answer may be wrong—even if calculations are correct.

 

Kick Intensity Explained 

Kick intensity indicates how severe the kick is and helps assess risk.

 

IWCF Kick Intensity Formula

Kick Intensity (psi)=Formation Pressure−Hydrostatic Pressure

📌 Important:This value is numerically equal to SIDPP in a shut-in well.

 

Exam Scenario 2 – Kick Intensity

From previous example:

• Formation Pressure = 5,130 psi

• Hydrostatic Pressure = 4,680 psi

5,130−4,680=450 psi

✅ Kick Intensity = 450 psi

 

📌 IWCF Insight:If SIDPP is high → kick severity is high → risk increases.

 

Formation Pressure Gradient (Advanced Exam Logic)

Sometimes IWCF asks for pressure gradient, not absolute pressure.

IWCF Formula

Formation Pressure Gradient=Formation PressureTVD

 

Exam Scenario 3 – Gradient Calculation

Given:

• Formation Pressure = 5,130 psi

• TVD = 9,000 ft

5,1309,000=0.57 psi/ft

✅ Answer: 0.57 psi/ft

 

📌 Why this matters:Pressure gradients are used to:

• Identify abnormal pressure zones

• Compare against mud pressure gradient

 

Common IWCF Exam Mistakes (Kick & Formation Pressure)

❌ Forgetting to calculate hydrostatic pressure first

❌ Using SICP instead of SIDPP

❌ Mixing static and circulating conditions

❌ Calculating when only logic is required

❌ Rushing calculations without unit checks

 

How IWCF Frames Kick-Related Questions

IWCF rarely asks:

“Calculate formation pressure.”

Instead, it asks:

• Is the well underbalanced?

• Is the kick severe?

• What is the correct next action?

• Is current mud weight sufficient?

📌 Correct Exam Approach:

Calculate → Interpret → Decide

 

How WellWise Helps Candidates Master Kick Calculations

At WellWise Consultancy, candidates learn:

• When to calculate and when not to

• How to identify correct pressure inputs

• Exam-style calculation drills

• Diagram-based kick scenarios

• ARI simulator exercises linking pressure to well behaviour

 

Final Exam Tip (Very Important)

If the well is shut in and static:

• Use SIDPP

• Formation Pressure = Hydrostatic + SIDPP

 

If you remember this, half the IWCF calculation questions become easy.

(This article is part of our IWCF Drilling Calculations Series. Read Blog 1 on Hydrostatic Pressure Calculations and Blog 3 on Pump Output Calculations for complete exam preparation.)