Engineering module

Critical speed — drillstring vibration

The BHA and drill string are modelled in three dimensions to find the critical rotary speeds where axial (bit bounce), lateral (whirl) and torsional (stick-slip) vibrations are excited — including motor-driven bits, RSS, stabiliser placement and WOB effects.

What it computes

Key outputs

Critical speeds by vibration family
RPM avoid-bands against the planned speed
Campbell diagram
Mode shapes and string contact points
Criticals vs depth (roadmap) and vs WOB

Critical speed results showing natural frequencies by mode family and avoid-speed bands — Natural frequencies by mode family, and avoid-speed bands in RPM.

Avoid-bands across the section

The roadmap re-solves the string at successive running depths, so the RPM windows to avoid can be read off for the whole section rather than a single point in the hole.

Avoid-speed bands plotted by vibration family against surface rotary speed — Critical speeds by mode family across surface rotary speed.

Note

Scope

The screens on this page show dummy sample data.

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