Studies on NMR logging responses at formation boundary
核磁共振测井地层界面响应特征研究

The formation signal is measured by Nuclear Magnetic Resonance(NMR)logging tool in the moving state.Researches on the effect of vertical logging speed on NMR logging responses can provide a sound basis for tool design and data interpretation.The logging response equation at the formation boundary was proposed in this paper.The logging responses at the single, symmetrical,and asymmetrical boundaries were simulated.And the factors affecting NMR logging response were discussed.It is suggested that the NMR logging responses were greatly affected by tool moving.The main factors are:antenna length,logging speed,waiting time, running average,signal to noise ratio and thickness of formation.With the increase of antenna length,logging speed,running average and waiting time the vertical resolution decreases. Suggestions about how to improve NMR logging vertical resolution were proposed in the last part of paper.