A Multifunctional Bottomhole Power Drilling Tool Rotary Speed Sensor Based on Triboelectric Nanogenerator

The rotary speed of bottomhole power drilling tools during drilling operations provides feedback on bottomhole assembly malfunctions and borehole trajectory anomalies. However, existing rotary speed sensors suffer from limitations in their power supply methods, leading to reduced drilling efficiency and increased costs. This study presents a novel multifunctional rotary speed sensor with self-powered capabilities based on a triboelectric nanogenerator. Utilizing the triboelectric effect and electrostatic induction generated by the rotation of the bottomhole assembly, the sensor outputs triboelectric pulses correlated with rotational speed, enabling the measurement of both rotational speed and angle. Experimental results demonstrate a measurement range of 0 to 1000 rpm for rotational speed, an angular resolution of 30 degrees, a measurement error of less than 3.2%, and a maximum power output of 6.4 µW. The sensor operates reliably within a temperature range of 0 to 160 degrees Celsius and a relative humidity range of 0 to 90%, exhibiting excellent performance. Compared to conventional downhole sensors, the developed sensor’s self-powered functionality makes it more suitable for actual downhole operating conditions.