Research And Implementation Of Formation Resistivity Measurement Based On Electromagnetic Wave Propagation Theory

LWD Electromagnetic Propagation Resistivity Logging(EPR) is one of the most effective methods to Formation Correlation and Evaluation in real time. It gets rid of the inherent disadvantage of conventional wireline logging that can't retrieve the information of logging in real time, estimates the resistivity of undisturbed formation in high resolution. It is one of the hotspots in domestic corresponding research field recently. The thesis makes a thorough discussion into EPR logging method and designs corresponding equipments, associating with the project of LWD Geosteering Logging System.The thesis introduces Three-Antenna EPR model, based on this model we use a symmetric compensatory logging architecture. We analyse and compare two phase detective methods respectively using analog phaselock technique and digital signal process, propose a digital signal process based system architecture.We compare and analyse correlation function analysis method and FFT spectrum analysis method, and present an improved one based on FFT spectrum analysis method. Simulate experiments convince that the improved one better restrains the energy leak of sampled signal and increases the measuring precision of the phase difference.We design function modules including frequency selecting amplifier circuit, automatic gain control circuit, A/D transfer circuit and digital signal process circuit according to the requirements of system functional implement and technical metrics. Debug results and tests of engineering prototype show that our system is designed rationally, the method works, and the measuring results fulfill every metrics of the EPR Logging.