The Design And Research Of The Logging While Drilling Sonic Caliper Control System

With the development of national economy dependent on energy will be more and more big, the energy has become an important strategic resources that direct impact on national security, social stability and economic development. Oil as the main part of energy, its importance is self-evident. In the process of oil drilling, well logging is an indispensable link. How to well logging low cost and high efficiency has been the common pursuit goal of petroleum enterpriseAs the logging while drilling logging is more accurate and better economic benefit and better real-time performance compared with conventional wireline logging information,in the present foreign oil drilling, Marine open hole measuring almost all adopt logging while drilling technology. In a lot of land oil field, there are a lot of risk in the application when adopt the existing cable logging technology,so usually used while drilling logging technology to complete the measurement of open hole. However, the domestic study of logging while drilling started relatively late, there is no drilling logging instrument with full independent intellectual property rights. Therefore, the study of logging while drilling technology has important practical significance and application value.This thesis main research caliper test with While drilling in the open hole,according to the size of open hole well data, to carry out the follow-up of the cementing job or related work decisions.In this thesis, introduction part of chapter1introduces the purpose and significance of logging while drilling technology research, and the development situation at home and abroad. Measuring principle part of chapter2introduces the characteristics of ultrasonic and the principle of logging diameter measured with ultrasonic, and expounds the difficulties of this topic; Echo testing method and data processing part of the chapter3introduces two kinds of methods of the echo detection and the corresponding data processing algorithms, and compare the two methods.Control system design and realization part of chapter4is the focus of this article, in this part, firstly, introduces the control system requirements, then introduced the control system overall framework design based on FPGA according to the control requirements and the selection of FPGA, DSP, AD. Then introduce the design and realization of the seven module in FPGA in detail and each module of the simulation results are given. Chapter5introduces the debugging process and the result of debugging. Chapter6giving summarization of this project and puts forward some prospects.In this thesis, the relationship of the ultrasonic transmission time, propagation velocity and the distance is used to measure Caliper. In the case of known ultrasonic transmission speed, calculating the caliper through inspection and record the transducer receives the echo time. Considering the accuracy of measurement and getting more information, full wave train detection methods are used in this thesis.After the echo signal is digitized,matching related method is used to get the echo time,and then calculate the caliper information. This paper mainly introduces the design and realization of the control system based on FPGA.This control system include seven module,there are State machine module, excitation signal module, AD data acquisition module, DA conversion module, command interpretation module, serial communication interface (SCI) module, and energy saving module. Among them, the excitation signal module produced excitation signal and multi-channel selector control signal.After the excitation circuit,the excitation signal incentives the transducer to produce ultrasonic. Multi-channel selector control four echo way of ultrasonic transducer. AD data acquisition module includes the design of FIFO and AD chip control, the module provide conversion clock for AD chip according to the command and after the Series switch,the data is Cached in the FIFO,which is designed in AD data acquisition module. DA module provides the conversion clock and write clock for DA chip, the transformed data as the input voltage for voltage controlled amplifier to control the magnification of the echo signal. Command interpretation module is responsible for receiving a command inoue.The command is converted into a binary number to send to the state machine.The caliper information is transmitted to the inoue according to the command. SCI module response for the communicationbetween DSP and FPGA. The coordination between these modules are uniformly by the state machine control. Through the analysis of the experimental debugging results, proved the correctness and the rationality of the design.