Design Of Acoustic Emission Circuit System Based On Remote Sensing Technology

In recent years,acoustic remote detection as the latest development of logging technology has achieved a breakthrough in logging detection technology from near wellbore to far wellbore.The detection range has been increased from several meters around the well to several tens of meters.In reservoir description and geology while drilling Orientation,timely identification of "sweets" and reservoir boundaries ahead,timely adjustment of borehole trajectory and drilling engineering parameters have shown great advantages.In order to improve the detection depth and meet the engineering reality,the excitation of high-power wide-frequency acoustic signals has become the key to the design of the sound wave far detection transmission circuit system.Limited by the high-temperature and high-pressure environment,the performance of high-power devices in the acoustic wave transmission circuit is degraded,and the output amplitude is unstable,which has become a problem faced by the technology at this stage.The single-pulse excitation method needs to increase the transmission pulse width or increase the transmission voltage to increase the transmission energy.However,increasing the transmission pulse width will reduce the imaging resolution,and increasing the transmission voltage poses new challenges to the transmission transducer.Conventional high-power acoustic wave transmission circuits use a transformer-driven transducer for excitation.Adjusting the transmission frequency must change the circuit parameters.It is difficult to meet the requirements of a wide frequency band due to the frequency characteristics of the transformer and the transducer.This article is aimed at the requirements of logging tools,combine with actual engineering needs to develop wide-frequency and high-power transmitting circuits,which is used to drive a low-frequency transducer for the SWD(Seismic While Drilling)detector.The circuit can generate bipolar pulse signals with different frequencies and controllable voltage to drive the wide-frequency transducer LTB2016 to emit acoustic signals.On this basis,to design the control logic module of acoustic emission circuit system that based on FPGA,and complete the hardware design of the high-voltage power supply circuit,bridge switch circuit,acquisition circuit,and communication circuit.The innovations of this paper are:(1)To ensure the safety and efficiency of energy storage,the PWM technology is used to adjust the charging voltage,and the closed loop control algorithm is introduced to ensure the stability of the output voltage;(2)To meet the high-power broadband requirements of theexcitation signal,the full The bridge switch circuit realizes the output of bipolar pulse signals of any frequency;(3)In order to ensure the safety isolation of the control module and the power transmission module,taking into account the small volume and low frequency transmission requirements,the modulation technology is used to change the low frequency transmission control signal into a high frequency signal to meet the requirements of the transformer small volume.Frequency signal rectification and filtering restores low frequency control signals.The test results show that:(1)The bipolar pulse signal can be stably output,the signal amplitude is adjustable in the range of 200V-3000 V,and the frequency is adjustable in the range of 200Hz-2000Hz;(2)The size reaches the expected design index,and it can work stably for long time under the environment temperature of150?;(3)Compared with similar technologies,the bipolar pulse signal excited by this system has higher working efficiency,and it is feasible to apply this system to logging while drilling.In summary,the acoustic wave detection and transmission circuit system implemented in this paper has the characteristics of large transmission energy,wide frequency range,high temperature resistance and small size.The overall structure of the system is reasonable,the integration is high,and the scalability is strong.The various performance indicators can meet the needs of the sound detection while drilling technology,and have a good application prospect.