The top drive is a critical piece of equipment in well construction. When the top drive fails, drilling halts and operations are suspended until the machine is fixed, at considerable cost to all parties. Literature and survey data reveal that top drive failure is among the leading causes of hardware-related non-productive time (NPT) on drilling rigs. The objective therefore is to detect a failing top drive hours or even days before it can no longer function effectively, and pro-actively maintain it before catastrophic failure takes places. In this paper, three separate health monitoring techniques are considered for a top drive: thermal analysis, vibration analysis, and oil analysis. Appropriate sensors are suggested for each of the three analyses, and are described in this paper. The paper also details a thermal model and a fault detection algorithm used to monitor the lubrication and electric motor subsystems of an AC electric top drive. These algorithms have been implemented and deployed in the field. Since no faults have occurred to date in the top drives on which these algorithms have been deployed, simulation results are presented for artificially induced faults. The advantages and disadvantages of other relevant sensor technologies and methodologies are studied and discussed. It is shown that the upfront cost of the sensors and the data acquisition system can easily be recouped by preventing one to two top drive failures. Additionally, the thermal analysis method described can be conducted with the existing sensor suite available on most top drives. This novel methodology can be easily implemented without the need for complex sensors, and is expected to make a meaningful, positive contribution to lowering NPT associated with rig hardware failures.

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