Swab/Surge Pressure Calculator
Swab/Surge Pressure Calculator works out the annular pressure change induced by pipe trip speed — surge (pressure increase) running in, swab (pressure decrease) pulling out — from hole/pipe geometry, viscometer dial readings, and mud weight, using Burkhardt's clinging-constant method for induced velocity plus a power-law (laminar) or Bingham-plastic (turbulent) pressure-loss correlation you select. Run it in reverse to solve for the maximum trip speed that keeps the pressure change within a target margin.
How It Works
Induced velocity = [0.45 + pipe OD²/(hole ID² − pipe OD²)] × trip speed (Burkhardt's clinging-constant relation). Surge = hydrostatic + pressure loss; Swab = hydrostatic − pressure loss, using either a power-law (laminar) or Bingham-plastic (turbulent) annular pressure-loss correlation.
See every formula worked through in detail on the Completion Engineering Formulas reference.
When You'd Use It
Before tripping pipe in or out of the hole, engineers check whether the planned trip speed keeps surge pressure below a formation's fracture margin and swab pressure above its pore-pressure margin — or work backward from those margins to the fastest safe trip speed.
Key Features
Available Now
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