Design And Implementation Of NMR Adaptive Data Acquisition System

NMR logging tools use a set of pulse sequence measurement parameters during operation,which cannot guarantee the quality of data collected under different formation conditions,and frequent changes of pulse sequence measurement parameters by operators during the logging process will reduce logging efficiency.The quality and efficiency of resonance logging data acquisition,the design and implementation of an NMR adaptive data acquisition system that can adjust the measurement parameters in real time.Based on the NMR logging principle prototype,this paper completes the main control circuit of the NMR adaptive data acquisition system that can adjust the measurement parameters of the pulse sequence in real time,including the hardware design of the main control circuit,the DSP firmware design of the main control circuit and the main control circuit FPGA firmware design.The main control circuit of the NMR adaptive data acquisition system adopts DSP+FPGA architecture,which can be divided into DSP module,FPGA module,storage module,communication module and data acquisition module according to the function.DSP,as the main controller,controls the running state of the instrument,and completes the processing of nuclear magnetic data and real-time adjustment of pulse sequence measurement parameters;FPGA,as an auxiliary controller,generates pulse sequence control signals and data acquisition signals under the control of DSP;storage The module includes the SRAM module and the Flash module,which are respectively responsible for buffering the intermediate data in the NMR data processing process and storing the NMR data processing results;the communication module is divided into the RS-485 module and the CAN module,which respectively complete the communication with the ground host computer and the telemetry system.Communication;the data acquisition module converts the echo signal amplified and filtered by the isolation receiving board into a digital signal.The DSP firmware design includes the program control part and the nuclear magnetic data processing part.In order to enable the main control circuit to adjust the measurement parameters in real time,the DSP configures the FPGA by issuing commands,and the FPGA parses the commands and extracts the configuration parameters and control signals.Generate pulse sequence control signal and data acquisition signal,and then control the nuclear magnetic instrument to complete pulse sequence emission and data acquisition.The FPGA logic design includes SPI interface control module,command parsing module,pulse sequence generator,and receiving channel.The SPI module completes the communication between the FPGA and the DSP module;the command parsing module parses the commands issued by the DSP to generate configuration data or control signals;the pulse sequence generator generates pulse sequence control signals and collects data according to the configuration data and control signals of the command parsing module Control signal;the receiving channel receives the digitized echo signal and performs digital phase-sensitive detection.The designed NMR adaptive data acquisition main control circuit is jointly debugged with the principle prototype after firmware simulation and hardware debugging.The results show that the designed NMR adaptive data acquisition system has realized the basic functions of adaptive data acquisition.