Positive displacement motors (PDMs) have been extensively utilized in the North America unconventional market. PDMs are frequently run with aggressive parameters in challenging drilling environments to increase drilling performance. Because PDMs are typically rental equipment, there is often not much information givento the equipment owners when tools are returned after use. This situation limits the opportunities for failure investigation, preventive maintenance, and tool design optimization. Furthermore, measurement-while-drilling (MWD) tools in PDM bottom hole assemblies (BHAs)only measure dynamics of the drill collars, considerably above the motor, often without sufficient resolution to understand adverse drilling dynamics and to design remedial actions for the operations.
A dynamics measurement data recorder was developed and introduced for this type of operation. The data recorder is a small, low-cost, and battery-powered device. It is installed in the rotor catch of a conventional PDM in such a way that no additional component is added to the BHA length. The recorder is fitted with a triaxial vibration accelerometer, a triaxial shock accelerometer, a gyroscope and a temperature sensor. The recorder can log data over a full PDM operation cycle, including shipment, rig-side handling, and downhole operation.
The data recorder has been deployed in North American land operations since 2016. One case study is presented, and the data analysis showed that PDM operation cycles were captured from the installation of the recorder in maintenance bases to the return of the tools. Torsional vibrations and stick-slip generated by mudmotors during sliding phases were effectively captured. In several cases, bit dull grade conditions were correlated with recorded drilling dynamics data as part of failure analyses to understand the root cause of the problem.