Which rig instrument helps the driller monitor the amount of mud displaced by the tubular or wire rope being run in and pulled out of the hole?

Which rig instrument helps the driller monitor the amount of mud displaced by the tubular or wire rope being run in and pulled out of the hole?

• A. Trip Tank Volume Indicator
• B. Mud Return Flow-Rate Indicator
• C. Rotary Tachometer
• D. Pump Rate Gauge

Answer: (A)

When you run in or pull out pipe or wire rope, mud is displaced from the hole and must be accommodated in the surface system. The Trip Tank Volume Indicator directly monitors the change in mud volume in the trip tanks as that displacement occurs, giving a measure of how much mud has been moved with the string. This helps the driller keep the mud balance right so the hydrostatic pressure at the bit stays stable and kicks are avoided during tripping. The other instruments don’t track this displaced volume: a Mud Return Flow-Rate Indicator shows how fast mud is returning, not the total amount displaced; a Rotary Tachometer measures the rotational speed of the drill string; and a Pump Rate Gauge indicates how much mud is being pumped, not the volume displaced by tripping.

When you run in or pull out pipe or wire rope, mud is displaced from the hole and must be accommodated in the surface system. The Trip Tank Volume Indicator directly monitors the change in mud volume in the trip tanks as that displacement occurs, giving a measure of how much mud has been moved with the string. This helps the driller keep the mud balance right so the hydrostatic pressure at the bit stays stable and kicks are avoided during tripping.

The other instruments don’t track this displaced volume: a Mud Return Flow-Rate Indicator shows how fast mud is returning, not the total amount displaced; a Rotary Tachometer measures the rotational speed of the drill string; and a Pump Rate Gauge indicates how much mud is being pumped, not the volume displaced by tripping.