Design Of Near-probe Acquision Module Of Multipole Acoustic Logging While Drilling Tool

In recent years,in the process of economic development,oil provides indispensable energy support for all walks of life in modern society,so it is necessary to improve the oil exploration capacity to exploit more oil resources.With the development and progress of computer science and technology,the requirements for Logging while drilling(LWD)acoustic logging tools are becoming higher and higher,and logging tools need to be upgraded to meet the requirements.The design of near-probe acquisition module for multi-pole acoustic logging tool with drilling is part of the "key technology research of multi-pole circuit with drilling" in China's large oil and gas field and coalbed methane development project.Multipole acoustic logging tool with drilling has great advantages for logging environment of highly deviated wells and horizontal wells,which belongs to China's own research and development.The design of the LWD multipole acoustic logging tool is an upgrade version of LWD monopole acoustic logging tool,which has high value and includes the joint logging of monopole,dipole and quadrupole with multiple sound source modes.The downhole instrument mainly includes three parts: The first part is the near probe acquisition module which is responsible for weak signal conditioning and high-precision acquisition,the second part is the main control circuit which is responsible for data processing and storage,and the third part is the emission module which is responsible for acoustic excitation.This thesis focuses on the design and implementation of the near probe acquisition module of LWD multipole acoustic logging tool.Firstly,the thesis introduces the overview of the multi-pole acoustic logging tool.Secondly,the key technical problems in the design of near probe acquisition module are analyzed,and the overall design of the near probe acquisition module is given;Next,this thesis focuses on the description of the near probe acquisition module,including the composition of the hardware circuit and the software design process.The hardware circuit design focuses on the analog signal conditioning circuit design and noise analysis,MCU&ADC architecture and some peripheral circuits and PCB board interface layout.The analog signal conditioning circuit design mainly completes the amplification,filtering and automatic gain function of the weak signal generated by the acoustic receiver transducer.MCU&ADC architecture is the core circuit,which mainly completes the overall control of the acquisition module,signal acquisition and communication with the main control circuit.Software design mainly includes BOOTLOADER program design and MCU user program design.The BOOTLOADER program is used to update the MCU user program;The MCU user program mainly completes the ADC acquisition control,data processing and data transmission.Lastly,under the condition that the important circuit test of the near probe acquisition module is normal,the thesis carries on the high temperature experiment to the acquisition control circuit board and the flume experiment to the whole logging instrument system,and gives results and analysis,indicating that the downhole near probe acquisition module meets the design indicators.