Improving the Anti-Vibration Performance of Near-Bit Measurement System with High-Temperature Resistance

Aiming at the problem that sensors of the near-bit measurement system with high-temperature resistance easily damage under the strong vibration of the well drilling, this paper puts forward an structural optimization schemes through data analyzing and numerical simulation, and conducts filed tests. After analyzing previous data, it was found that violent vibration of the drilling string is the main cause of the rupture of the gamma sensor photomultiplier tubes and the damage of sensor flux gates. Results of finite element simulation show that the battery part of the near-bit measurement system has the largest amplitude (5.1 mm) and low intrinsic frequency (652Hz), and is easier to resonate with the bit, which increase the risk of damaging for the internal parts of the measurement system. Therefore, this paper proposes two key optimization measures: one is to fix the circuit part of the measurement system through cover plates, so as to reduce the relative motion between components; the other is to use the fluorine rubber with high compressive strength and excellent elasticity as the vibration attenuation material, and enhance the vibration attenuation effect through the overfilling way. Results of simulation show that the intrinsic frequency of the measurement system increases by 47% on average, and the maximum amplitude reduces by 23.8% on average, which significantly enhances the anti-resonance performance. Results of field tests show that the well entry time, cycle time, pure drilling time and drilling footage of the optimized measurement system increase, and the using of it in terms of well depth exceeds 6,000 m, which demonstrate the improvement of the anti-vibration performance. This paper can provide reference for improving the anti-vibration performance of the near⁃bit measurement system with high-temperature resistance.