Chinese Journal of Geophysics · 2007 · 18 citations · 9 references
EngineeringGeologyPetroleum EngineeringPetroleum GeologyPetrophysicsReservoir CharacterizationMagnetic Resonance ImagingMagnetic Resonance Pulse SequencesMagnetic Resonance Signal FormationPetrophysical AnalysisPetrophysical EvaluationRelaxation MechanismsDistribution Of Relaxation TimesMagnetic Resonance Relaxation TimesNuclear Magnetic Resonance RelaxationNuclear Magnetic Resonance RelaxometryPetrophysical CharacterizationRelaxation TimesT2 RelaxationTransverse Relaxation Time
Abstract Multi‐exponential inversion of NMR (Nuclear Magnetic Resonance) relaxation signal has been widely used in petroleum industry both in core analysis for petrophysical studies and in logging interpretation for oil exploration. In order to obtain T 2 relaxation time distributions with high resolution in the case of low SNR (Signal‐to‐Noise Ratio), we use simulated and experimental data to analyze the effects on the inversion of the number of pre‐selected relaxation times, the number of spin echoes acquired, and the compression in time domain of the spin‐echo trains. We found that reducing the number of echoes acquired can cause divergent behavior for the long T 2 components, changing the number of windows for data compression does not change the shape of the inverted T 2 distribution significantly. We also studied the effect of different SNRs on inverted T 2 distributions for different inversion algorithms. We found that the response to different SNRs for different algorithms is different, and suggested using an adjustment parameter to correct such effects.
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