A Research Of Peak Detection Method And Design Of Energy Spectrum Capture And Storage Module For LWD Desity Logging Tool

The Density LWD(Logging-While-Drilling)Tool is an instrument that acquire,process,and store signals generated by gamma rays reacting with formation materials to obtain the parameters required for formation evaluation.The energy spectrum acquisition storage module is one of the core modules of the instrument.It is mainly used for acquiring,processing and storing the signals detected by the probe.The energy spectrum acquisition storage module mainly comprises an analog circuit part and a digital circuit part.The analog circuit is a peak detection circuit,which is used for detecting the peak value of the probe output waveform.It is convenient for subsequent acquisition.This thesis is divided into three parts: project design,project implementation,and project verification.Firstly,combined with the overall structure and workflow of the Density LWD Tool,the design requirements of the energy spectrum acquisition storage module are analyzed.The structure and workflow of the spectrum acquisition storage module is designed.Secondly,according to the requirements of energy spectrum acquisition storage module and the principle of peak detection circuit,a new peak detection circuit idea is proposed and a peak detection circuit is designed.According to the structure and workflow of the energy spectrum acquisition storage module,the hardware framework of the FPGA+MCU is determined,and the hardware circuit is designed,including the main processor module,the FPGA module,the ADC module,the communication module,the power supply module and the storage module.Then,the software logic is designed,including AD control module,energy spectrum drawing RAM module,sector information module,communication module,storage basic operation module,state machine and control signal generation module,check module,bad block management module and storage upper layer module.Finally,in the thesis,the performance of the peak detection circuit is verified and compared with the performance of the traditional peak hold circuit by simulation.A series of experiments are designed to test the signal acquisition,communication and energy spectrum data storage functions of the energy spectrum acquisition storage module.The energy spectrum acquisition storage module is connected to the probe,the high voltage module,the azimuth measurement module,and the caliper module for joint testing.The results show that the design of the energy spectrum acquisition storage module of Density LWD Tool has achieved the expected goal.