0 How to Determine Drilling Mud Motor Failure

At the drilling site, drilling mud motor failure downhole may be happened from time to time. The questions that are usually raised are things like "How do I know if the it fails down hole?" and "What indications will I see that this has happened?" etc. Due to this, I would like to share my personal experience regarding the mud motor failure and its symptoms.

The following signs indicate that you may be faced with downhole mud motor breakdown.

Frequent Motor Stall - Motor stall happens when the rotor of the mud motor has stopped moving. Typically, the motor stalls only with a high differential of pressure. However, if the down hole equipment doesn't perform as normal, it will get stalled with by a small amount of differential pressure. For instance, a mud motor normally drills at 400 psi differential pressure, but if it is stalled out with only 100 psi you can suspect the problem is with the motor.

Pressure fluctuation while rotating - As you know, differential pressure it a set parameter while rotating down, not based on the weight on bit (WOB). Rotating with a good mud motor won't create pressure fluctuations, whereas a bad mud motor will show fluctuation in stand pipe pressure and you may not be able to maintain constant pressure.

Abnormally high surface pressure - A stator is made of rubber. When the stator rubber is worn out and breaking into pieces, small parts of rubber can jam the flow path in the motor or a drilling bit. This situation also results in high stand pipe pressure.

Reduction in rate of penetration - If there are no changes in formation and drilling parameters, the decreasing in ROP (Rate of Penetration) may be caused by failure of the down hole tool. Moreover, if the took is severely damaged, you will be able to drill any footage.

What should you do if the problem is clearly identified?

The only thing you can do is pull out of the hole and change a new tool. It is almost impossible to drill with a damaged drilling motor unless you only have a few feet to the well target depth. If you continue drilling with a bad tool, the down hole tool may be parted and lost in the well.

With the mentioned indicators of mud motor failure above, you should be able to identify your suspected problem and begin troubleshooting as soon as possible to minimize unproductive time on a drilling rig.

Rachain J. is working in drilling operations and he would like to share basic knowledge about drilling formulas and drilling operations. He and this team member create very useful oilfield related websites which are drilling formulas and oilfiled dictionary.