页岩、砂岩岩心核磁共振实验结果对回波间隔的敏感性差异

回波间隔(TE)参数的选取对核磁共振岩心分析实验结果影响很大,为确定TE值对不同岩样的核磁共振结果的影响程度,系统研究了页岩、砂岩岩心核磁共振岩心实验对TE值的敏感性。对相同状态下的岩心进行了多组TE值的核磁共振测量,分析了不同岩样核磁实验T2谱的形态、T2谱峰位置和核磁孔隙度与TE值的关系。结果表明,TE对于核磁共振岩心分析结果影响很大,而且对不同岩性岩心的敏感性有很大差异,砂岩岩心对TE值的敏感性较弱,不同TE值的测量结果,其T2谱的变化在形态上有所改变,但其主体位置和核磁孔隙度变化不大；页岩岩心对TE值非常敏感,不同TE值测量时,T2谱不但形态发生了明显的变化,而且其主体位置向右移动,核磁孔隙度也迅速减小。

Study on Sensitivity Difference of Shale and Sandstone Core NMR Experiment Results to TE

The appropriate echo interval (TE) can be used to accurately measure the results of nuclear magnetic resonance experiments. To determine the influence of echo spacing on the NMR results of different rock samples, the sensitivity of nuclear magnetic resonance core experiments to echo spacing is systematically studied. Different echo interval values were set by NMR instruments, and their effects on the morphology, T2 spectral position and porosity of the T2 spectrum of the rock samples were analyzed. The results show that the echo spacing has great influence on the results of nuclear magnetic resonance core analysis, and the sensitivity to different lithological experimental results is very different. The sandstone core has weak sensitivity to TE, and the T2 spectrum changes in morphology. It changed, but its main body position and envelope area did not change much; the shale core was very sensitive to TE, and the T2 spectrum not only changed its shape, but also its body position moved to the right, and the envelope area also decreased rapidly.