Research On The Acoustic Logging Tool Downhole Data File System

With the unceasingly rich and development of acoustic logging tools,especially with the development of LWD acoustic logging tools and large-scale array acoustic imaging logging tools,the requirement of downhole storage of logging data becomes more and more important.However,at present,the acoustic logging downhole storage adopts the way of driving physical memory direct,which not only increases the difficulty of instrument development,but also reduces the accuracy of data in the process of access.Therefore,it is necessary to introduce "file system" into acoustic logging tools to manage logging data and realize data "access by name".Firstly,this thesis introduces the development status of the embedded file system and analyzes the necessity of downhole storage of the logging tools by taking the LWD acoustic logging tools and the far azimuthal acoustic reflection logging tool as an example.Then,on the basis of DSP controller,the control circuit of downhole data storage is designed by FPGA control NAND Flash.Next,the software structure idea of layered realization of downhole data file system is proposed.Based on the embedded file system FatFS,the FAT file system is established and run stably on NAND Flash by designing the FTL.This paper introduces the FatFS file system and its migration process simply,and discusses the implementation process of FTL in detail,including Address Mapping,Bad Block Management,ECC and Balanced Friction modules.Finally,based on the STM32 development board and the upper computer software,designing the test system of the file management system,and testing the file management system through this system.The test results show that the system can meet the current requirements of acoustic logging tools downhole storage.