Tripping Calculations Explained

How to Avoid Kick Scenarios During Tripping

In the IWCF Drilling Well Control exam, tripping-related questions are designed to test whether candidates understand how bottom hole pressure changes when pipe is moved — not just whether they can use formulas.

Many candidates fail these questions because they:

• Forget the difference between dry pipe and wet pipe

• Ignore displaced volumes

• Focus on calculations instead of well control logic

 

At WellWise Consultancy LLC, we train candidates to approach tripping questions the IWCF way — recognise the condition first, then calculate only if required.

 

Why IWCF Focuses on Tripping Calculations

Tripping is a high-risk operation because:

• Pumps are OFF

• Friction pressure is zero

• Hydrostatic pressure can drop suddenly

• Swabbing effects may occur

 

📌 IWCF Exam Insight:Most kicks during drilling occur while tripping, not while circulating.

 

What Happens to Bottom Hole Pressure During Tripping?

When pipe is pulled:

• Steel volume is removed from the well

• It must be replaced with mud

• If mud replacement is delayed or incorrect → pressure reduction occurs

📌 Key IWCF Rule:Any reduction in hydrostatic pressure during tripping can cause a kick.

 

Dry Pipe vs Wet Pipe – Critical IWCF Distinction

Dry Pipe

• Drill pipe is empty

• No mud inside pipe

• Larger pressure drop risk

• More dangerous

Wet Pipe

• Drill pipe is filled with mud

• Internal hydrostatic pressure maintained

• Smaller pressure drop risk

📌 IWCF Exam Rule:Dry pipe causes greater hydrostatic pressure reduction than wet pipe.

 

IWCF Tripping Calculation Concept (Not Just Formula)

IWCF wants you to understand:

• What volume is removed

• What volume must be replaced

• How much pressure is lost

Not every tripping question requires full calculation.

 

Exam Scenario 1 – Identifying Dry Pipe Risk (No Calculation)

Given:

• Pumps OFF

• Drill pipe pulled without filling

• Sudden flow observed at surface

 

Question

What is the most likely cause?

✅ Correct Answer:Hydrostatic pressure reduction due to dry pipe

📌 IWCF Logic:No circulation + pipe removal + no fill = pressure drop.

 

IWCF Formula – Pressure Loss Due to Pipe Removal

When calculation is required, IWCF may test pressure loss due to removed volume.

General Logic

• Calculate displaced volume

• Convert volume loss to pressure loss

• Compare against formation pressure

 

Exam Scenario 2 – Pressure Loss Calculation (Exam Style)

Given:

• Drill pipe capacity = 0.0178 bbl/ft

• Length pulled = 1,000 ft

• Mud weight = 11.5 ppg

Step 1: Volume Removed

0.0178 × 1000 = 17.8 bbl

Step 2: Pressure Loss

Pressure Loss = 0.052 × MW × Equivalent Height

(Height derived from annular capacity — often simplified in exam questions)

📌 IWCF Tip:If IWCF provides pressure loss directly, do not recalculate.

 

Wet Pipe Tripping – Why It’s Safer

With wet pipe:

• Mud inside pipe replaces steel volume

• Hydrostatic pressure loss is minimal

• Kick risk is reduced

📌 Exam Favourite Question:“Which condition is safer during tripping?”

✅ Answer:Wet pipe

 

How IWCF Frames Tripping Questions

IWCF rarely asks:

“Calculate tripping pressure loss.”

Instead, it asks:

• Is the well safe while tripping?

• What is the main risk?

• Should the hole be filled?

• Which condition increases kick risk?

📌 Correct IWCF Thinking:

Pressure reduction → Underbalance → Kick risk

 

Common IWCF Exam Mistakes (Tripping)

❌ Forgetting pumps are OFF

❌ Using ECD during tripping

❌ Ignoring pipe fill procedures

❌ Treating dry and wet pipe as equal

❌ Over-calculating when logic is enough

 

How WellWise Helps Candidates Master Tripping Questions

At WellWise Consultancy, candidates learn:

• Visual tripping scenarios

• Dry vs wet pipe comparisons

• Exam shortcuts to identify kick risk

• Simulator-based tripping exercises

• Decision-making under static conditions

 

Final Exam Tip (Very Important)

Always remember this:

Dry pipe + pumps OFF = highest kick risk.

Wet pipe + correct fill = safer tripping operation.

If you answer tripping questions with this logic, you will not be trapped in the IWCF exam.

 

What’s Next in This Series

Slug Calculations, Pit Gain & Riser Margin – IWCF Drilling Calculation Traps Explained