Design And Implementation Of Downhole Control And Processing Circuit For Circumferential Borehole Ultrasonic Imaging Logging Tool

As an important non-renewable raw material in the field of industry,petroleum nowadays plays an important role in industrial and social development.Ensuring and improving oil exploration and exploitation are of great significance to maintaining social stability and promoting development in both industrial and economic.With the everincreasing demand and exploitation intensity of petroleum,the monolithic sandstone oil reservoir with porous structure and high exudation rate has become much more difficult to find.Therefore,the research and development of high-performance logging tools with heavier duty,better accuracy and higher efficiency to deal with the exploration of potential petroleum reservoirs with more complex structures and greater logging defects has become the focus of major petroleum exploration and exploitation companies.Ultrasonic imaging logging technology is an emerging logging technology based on the development of multidisciplinary science and technology such as information technology,television imaging technology and computer technology.It is one of the important branches of the downhole logging field nowadays.On the basis of the ultrasonic transducer technology and the physical principles of sound wave transmission and reflection,the ultrasonic imaging logging technology can visually reflect the reservoir circumstance of downhole fractures in the form of imaging maps by extracting key information from ultrasonic echo signals.It has the advantages of high imaging resolution and intuitive reflection of logging information with high reliability.This thesis mainly discusses the hardware circuit design and the main controller software design for the downhole control and processing circuit of Circumferential Borehole Ultrasonic Imaging Logging Tool(CBUILT).The thesis first introduces the background and significance of the research project,summarizes the development and research status of ultrasonic imaging logging technology at home and abroad.Then it introduces the instrument system from the aspects of overall structure and the principles of ultrasonic imaging logging that applied by the CBUILT.Afterwards,the requirement analysis of the design index and function positioning of the downhole control and processing circuit is carried out,based on which the overall circuit structure design plan and the instrument work flow plan are proposed later.According to the hardware circuit module division of the overall structure design,the thesis focuses on the circuit design and implementation of each hardware function module,and discusses the function realization,design ideas and working principles of each circuit module.The software design is based on the hardware function module design and the instrument function requirements.It focuses on the design and implementation of the user logging program for PIC microcontroller including functions such as the interactive communication,upper computer instruction analysis and processing,automatic gain control of the programcontrolled amplifier module.In addition,the thesis also introduces the principle of the PIC online program upgrade function and the design and implementation of FPGA control program for the signal conditioning channel time-varying gain module.Finally,this thesis analyzes the function and performance of the downhole control and processing circuit from the aspects of laboratory single board debugging and instrument system joint test,verifying the realization of various functions,then briefs the key problems encountered during the debugging process with solutions purposed.The results of the single board debugging and the instrument system joint test under actual test environment show that the downhole control and processing circuit of the CBUILT meets with the variety of design requirements at this stage.