Trip margin is an increment of drilling mud density to provide overbalance so as to compensate the swabbing effect while pulling out of hole.
You can quickly calculate how much trip margin required by this following simple equation.
Trip Margin = Mud Yield Point ÷ [11.7 x (Hole diameter – Drill pipe diameter)]
The unit of each parameter is as follows;
Trip Margin in ppg (pound per gallon)
Mud Yield Point in lb/100 sq ft
Hole diameter in inch
Drill pipe diameter in inch
Let’s try to determine the trip margin with the following information.
Mud Yield Point = 12 lb/100 sq ft
Hole diameter = 10 inch
Drill pipe diameter = 5 inch
Trip Margin = 12 ÷ [11.7 x (10 – 5)] = 0.2 ppg
Please find the Excel sheet to calculate Trip Margin – -> Trip Margin Calculation Sheet