Design And Implementation Of An Electromagnetic Wave Resistivity Logging Tool

In the process of oil drilling,the geometrical parameters of the drill bit can be measured synchronously to provide accurate real-time data for the rotary-oriented drilling,so that the drill bit can pass through the oil and gas reservoir accurately and improve the oil and gas recovery.The electromagnetic wave resistivity logging tool while drilling is an indispensable part of the measured data because of the capability of measuring the formation resistivity with excellent accuracy and reliability.Our research group had analysed the feasibility of electromagnetic wave resistivity measurement instrument of the single transmitter-double receiver structure qualitatively,so this paper designed a kind of electromagnetic wave resistivity logging system.The relationship between amplitude ratio,phase difference and characteristic resistance can be actually measured.The measurement system was the key of this design.Considering the results the research group already had,this instrument was located in the compact electromagnetic wave resistivity logging tool with practical value.The details of major work in this paper were as follows.Aiming at the application object selection of an electromagnetic wave resistivity logging tool,this paper makes a theoretical analysis.First of all,the structure of the single transmitterdouble receivers logging tool was theoretically analyzed,and so did the principle of compact logging analysis.Then,the feasibility of orthogonal sampling algorithm is analyzed in detail.Finally,the application objects and main data processing methods of the design measurement system were determined.According to the hardware circuit of logging instrument,the basic structure of hardware circuit is designed by simulation and electronic assistant software.The circuit design of signal generation circuit,signal filtering circuit,signal amplifying circuit,signal collecting circuit,digital processing system circuit and so on are completed.In view of the function realization of logging tool,this article has realized the request of each part through the software programming.At last,this paper has completed digital frequency synthesizer based on the Field-Programmable Gate Array(FPGA),signal frequency control based on the Direct Digital Synthesizer(DDS),low-pass filter design based on Matlab,the amplitude ratio and phase difference extraction algorithm based on the Digital Signal Processor(DSP),data storage and PC machine communication etc..In the light of the performance test of logging tools,the measuring system designed in this paper has been tested by the resistance ring experiment.The experimental results were compared with the simulation results.The performance of the designed logging tool met the requirements of the principle prototype,and can be further improved to have higher practical value.