1. n. [Drilling Fluids]

Another term for gel strength in a fluid. Shear strength opposes the movement of mud, whether by pumping or movement of pipe in a wellbore. Excessive shear strength can develop after a mud has been quiescent in the hole at high temperature for a period of time. Shear strength can be measured according to procedures published by the API.

See: gel strength,  lost circulation,  shear-strength measurement test