Detection of Drill String Whirl Posted in: AR700 Laser Displacement Sensor, Diameter Measurement, Displacement Measurement, Updates – Tags: Civil Engineering, Mining, Oil and Gas

Acuity distance sensors are currently in the field measuring drill string whirl. It is certainly a difficult environment, but our AR700 line of sensors have the accuracy and the durability to take on this demanding task.

Drilling through the earth requires enormous force. That force is exerted on a drill bit through an ever increasing length of pipe. This assembly is known as the drill string. As the drill string gets longer, that enormous force can cause destructive lateral vibrations called “whirl.”

As the name suggests, whirl isn’t a simple back and forth motion. The whirl wobbles the drill string in a circle. The direction of this rotation is important, not just for identifying the cause of the whirl but for assessing the potential damage on the drilling equipment. Forward whirl – whirl in the same direction as the bit rotation – can cause damaging wear on components. Backward whirl – whirl in the opposite direction as the bit rotation – can be catastrophic.

If this destructive lateral vibration gets to the point where the rotating drill string or bottomhole assembly (BHA) rotates wildly off its geometric center, it can cause the drill string to roll or bang against the walls of the borehole.

In our Acuity sensor measurement application to prevent this type of drilling error, three Acuity AR700-16s were mounted 120 degrees from each other around the drill collar pipe. This allows not just the speed but also the direction of the whirl to be measured instantly.

It might not be immediately obvious why three sensors would be needed. To illustrate, take a look at the same situation with two sensors.

With only two sensors, every point in the drill string’s whirl will have a mirrored point where the sensors will read exactly the same. The only exceptions are when the drill string is closest to either sensor.

The AR700 has proven to be a valuable tool to prevent damage on far more expensive drilling rigs. This has kept both repairs and down time to a minimum. Whether you have a similar application or just think Acuity’s accuracy and toughness could help your application produce more and cost less, please contact our sales team at . We have a full line of laser distance sensors that can help your business make more with what they have.