The Two-dimensional NMR Logging Principle And System Design

Compared with the one-dimensional NMR logging, two-dimensional NMR loggingcan be used to achieve the identification of reservoir fluid from two Mathematicaldimensions. So that it is better to identify the complex formations about water gas andoil. But the majority of2D NMR logging is restricted to the research of principles andmethods, and not widely applied to the actual logging and applications.This thesis firstly introduces the principles and methods of two-dimensional NMRlogging. Based on the principles of diffusion-editing (DE) pulse sequence, this thesisproposed a basic observation mode which is convenient for the application of2D NMRlogging. Then, with the comparison of time sequence between1D NMR and2D NMR,this thesis gives the relationship between resolution, speed and SNR in2D NMR loggingapplications. Based on the principles of measurement in2D NMR, This thesis studiesgradient magnetic field, presents detailed comparison of several existing implements forstatic magnetic field, gives the realizing way of gradient field in2D NMR, and completesthe simulation of magnetic field. Based on the System Architecture of2D NMR logging,this thesis gives a digital integrated design approach which takes full advantages of DSPand FPGA, and completed the design of each module in control circuit of2D NMRlogging tool.Finally, combined with the instrument prototype of2D NMR logging tool, asystematic test of control circuit has been implemented under laboratory conditions. Theexperiment results show that, the design of control circuit and relevant logging sequencescould satisfy the requirement of applications in2D NMR logging.