Research And Realization Of Key Technology Of Downhole Main Control Circuit Of Quadrupole Acoustic Logging While Drilling Tool

Petroleum energy is the pillar of modern industrial development.At present,logging technology is the main technical means of petroleum exploration and development,and sonic logging while drilling(LWD)is an important branch of logging technology.The independent research and development of related technology is very important to protect China’s energy security.The quadrupole acoustic LWD tool is one of the most advanced instrument in the field of acoustic logging tool at present.The main control circuit is the core of the instrument,so it is necessary to control the operation process of the control instrument.In addition,some special functions should be added on the basis of it in order to increase the functionality and maintainability of the instrument.The research and realization of the key technology of the downhole main control circuit of the quadrupole acoustic LWD tool is a sub-subject of the major scientific research project "Key Technology Research of Quadrupole Acoustic LWD Tool " of USTC and COSL.The purpose is to improve the storage capacity,data processing capacity and data transmission capacity of the instrument.According to the requirements of the subject,this thesis mainly needs to complete the design of three functional modules.First,according to the interface characteristics of the peripheral of the main control circuit,the appropriate protocol and memory chip were selected,the reasonable driving function was designed,the reading and writing function of logging data and various auxiliary information was completed,the large-scale storage module with a capacity of 9GB was designed,and the memory management mode was optimized.Second,the downhole acoustic signals collected by various noise interference is serious,need to be in the main control circuit design of an effective digital filter for filtering processing,through MATLAB tools to acoustic logging signal time-frequency analysis,study the time-frequency distribution characteristic of noise,to choose the right means of filtering process,and the simulation test of the designed filter,The code was optimized and the filtering time of single channel waveform was less than 1ms to meet the need of real-time performance in the operation cycle.Third,in view of the main control circuit of large amount of data storage,the problems of ordinary serial transmission slow,need to be on the basis of the main control circuit,the completion of the data link layer and physical layer design of the circuit,choosing the appropriate protocol stack transplantation into main control circuit,through the transport layer protocol to achieve data transmission,control and management,coordination management communication and Ethernet transmission between nuclear function,Completed the design of Ethernet function,to achieve high-speed and stable transmission of data.At the end of each section,this thesis tests the realization of each function.After the successful test in the laboratory environment,the large-scale storage function and realtime filtering function are tested in the field.The experimental results show that the instrument works in a stable condition and each function is normal.The work in this paper reaches the expected design requirements.