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

Sensitivity Difference of Shale and Sandstone Core Nuclear Magnetic Resonance Experiment Results to Echo Interval

回波间隔的选取对核磁共振岩心分析实验结果影响很大,为确定回波间隔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回波间隔的敏感性。对相同状态下的页岩、砂岩岩心进行了多组回波间隔的核磁共振测量,分析了不同岩样核磁实验横向弛豫时间谱的形态、横向弛豫时间谱峰位置和核磁孔隙度与回波间隔的关系。结果表明,回波间隔对不同岩性岩心的敏感性有很大差异,砂岩岩心对回波间隔的敏感性较弱,回波间隔不同,其横向弛豫时间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;页岩岩心对回波间隔非常敏感,回波间隔不同,横向弛豫时间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。

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