Apparatus and method for detecting abnormal drilling conditions

摘要

Abnormal drilling conditions are detected by monitoring mud volume of the mud system or rate of change of the mud volume. In one embodiment, makeup mud is automatically added to the system as solids are removed from the mud. Abnormal conditions are indicated by when the rate of makeup mud addition differs from the rate of solids removal. The mud system is maintained at a substantially constant volume by means of tanks specially constructed to provide a small mud/air interface.