Research On Microseismic Data Acquisition Optimization And Time Synchronization

With the progress and development of electronic technology,computer technology and geophysical technology,microseismic monitoring technology has been widely used to guide the safe production of mines,tunnels and dam,and has been widely used in the hydraulic fracturing of oil and gas production.However,the domestic microseismic monitoring equipment starts late,develops slowly and relies heavily on the outside world.With the higher requirements of microseismic monitoring equipment on resolution,precision and channel number,the amount of microseismic monitoring data is increasing.In essence,there is a large amount of redundancy in the data of microseismic monitoring,so effectively removing the data redundancy has a crucial impact on the transmission and storage of microseismic monitoring data,and is also of great significance for the later seismic data processing.In the later seismic data processing,the microseismic monitoring data is connected through the time consistency between the acquisition nodes,and the accuracy of the time synchronization between the acquisition nodes has a greater impact on the accuracy of the microseismic positioning.Aiming at the problem of large amount of microseismic monitoring data and time synchronization,this paper uses STM32 + FPGA as the design framework,and mainly completes the design of microseismic data acquisition unit,optimization design of microseismic data acquisition,and time synchronization research of microseismic monitoring.The main research work is reflected in the following three aspects:First,in order to solve the problem of the current high dependence of domestic microseismic monitoring equipment,the design of a 12-channel high-accuracy,high-resolution microseismic data acquisition unit is studied.On the hardware,a signal conditioning circuit is designed which can adjust the original signal picked up by the sensor by 1-128 times gain.In the design of logic code,the functions of acquisition control and data reading of multiple ADCs are realized,and the SPI interface that communicates with STM32 is designed to transmit the data to the single-chip computer,and the single-chip computer performs data storage and transmission.Secondly,in order to solve the problem of large amount of microseismic monitoring data and outstanding redundancy,it is necessary to optimize the design of the collected data amount.It is proposed to use STA/LTA algorithm to identify the vibration signal and realize the microseismic data acquisition optimization from the perspective of hardware.With FPGA as the lead,complete the work of data buffering,filtering,and vibration signal identification.A custom SDRAM controller is used to implement data buffering.The FPGA is used for filter design and decimation filtering to reduce the signal rate,which reduces the design difficulty of the STA/LTA window and improves the signal-to-noise ratio.Utilizing the characteristics of FPGA pipeline operation,the DSP and the arithmetic operation unit inside the FPGA are reasonably called to realize the identification of the vibration signal,the redundant data files are removed,and the microseismic data acquisition is optimized.Thirdly,in order to realize the time synchronization between acquisition nodes,the method of STM32+DP83640 is adopted for time synchronization.Through the analysis of the principle of inhibits PTP protocol,packet processing,modification time synchronization software design framework,operating system transplant,LWIP protocol stack,inhibits PTP protocol source code,write DP83640 driver,and modify agreement code and make it get timestamp information on Ethernet physical layer chip,completed acquisition time synchronization between the nodes.Through test and analysis,the microseismic data acquisition unit designed in this paper can realize the microseismic data acquisition with high precision.In the case of different threshold parameters selection,the picking accuracy of vibration signals is above 90%,and it has been successfully optimized in the removal of data redundancy of microseismic data.Compared with the method of PTP time synchronization with time stamp in MAC controller,the clock synchronization realized in this paper has better stability and higher accuracy,and the time synchronization accuracy between nodes can meet the requirements of microseismic monitoring.