Surge & Swab Calculator

Calculate trip-induced pressure changes to optimize trip speed and prevent well control issues

Input Parameters

Enter wellbore geometry, mud properties, and trip speed

For closed-end (surge) calculations

Trip Speed Guidelines

  • Normal operations: 60-120 ft/min
  • Tight hole: 30-60 ft/min
  • Sensitive formations: <60 ft/min
  • POOH near shoe: Reduce speed

Surge/Swab Results

Enter parameters and click Calculate

Typical Surge/Swab Values

Trip Speed Surge EMW Swab EMW
30 ft/min+0.1-0.2 ppg-0.1-0.2 ppg
60 ft/min+0.2-0.4 ppg-0.2-0.4 ppg
90 ft/min+0.3-0.6 ppg-0.3-0.6 ppg
120 ft/min+0.5-0.8 ppg-0.5-0.8 ppg

Formula Reference

Surge/Swab Pressure (Burkhardt Model)

dP = (K x MW x V^n x L) / (1000 x (Dh - Dp)^(1+n)) Where: dP = Surge/swab pressure (psi) K = Consistency index MW = Mud weight (ppg) V = Clinging velocity (ft/min) L = Length of string (ft) n = Flow behavior index

Clinging Velocity

V_clinging = V_pipe x K_c K_c = 1 + (Dp^2 / (Dh^2 - Dp^2)) [Closed end] K_c = 1 + ((Dp^2 - Di^2) / (Dh^2 - Dp^2)) [Open end] Where: Dp = Pipe OD Di = Pipe ID Dh = Hole/Casing ID

EMW Equivalent

EMW_surge = MW + (dP_surge / (0.052 x TVD)) EMW_swab = MW - (dP_swab / (0.052 x TVD))

Simplified Estimate

dP (psi) ~ 0.052 x MW x V x L / (Dh - Dp)^2 EMW change ~ V / 100 x 0.3 ppg (rough estimate)