近年来，页岩油气勘探开发力度持续加大，诸多挑战随之而来．孔隙度是页岩储层评价和储量计算的重要依据，为甜点区确定和开发方案制定提供基础数据．低场核磁共振（LF-NMR）技术具有非侵入、无损特性，已成为页岩孔隙度测量的一种重要方法．但页岩NMR响应机制与常规砂岩和碳酸盐储层岩石具有显著差异，此外不当的实验参数和反演过程也可造成NMR孔隙度测量偏差甚至错误．本文首先利用T₁-T₂谱分别对干燥和饱和页岩进行含氢组分定性识别，然后基于均匀静磁场和恒定温度场下NMR信号与被测样品自旋质子数量成正比的特性提出了利用饱和地层水与干页岩的NMR自由感应衰减（FID）脉冲序列信号首幅值差异，经标定后直接测定页岩孔隙度的实验方法．实验结果表明，该方法提供的NMR孔隙度与称重孔隙度具有很好的一致性，消除了骨架含氢组分的背景信号影响．

In recent years, the exploration and development of shale oil and gas have expanded significantly, accompanied by numerous challenges. Porosity is a fundamental parameter for shale reservoir evaluation and reserve estimation, providing essential data for determining sweet spots and formulating development plans. Low-field nuclear magnetic resonance (LF-NMR) technology has unique non-invasive, non-destructive characteristics and has become a crucial method for shale porosity measurement. However, shale has substantially different nuclear magnetic resonance (NMR) response mechanisms from that of conventional sandstone and carbonate reservoir rocks. Furthermore, improper experimental parameters or inversion process can lead to errors or even faults in the measurement of shale porosity by NMR. In this paper, T₁-T₂ correlation is adopted to qualitatively identify hydrogen-containing components in dry and saturated shale. Based on the principle that NMR signal is proportional to the number of spin protons under uniform static magnetic field and constant temperature field, an experimental method is proposed to directly measure the shale porosity. This method calibrates with standard water sample, then compares the first amplitude of the NMR free induction decay (FID) signal between water-saturated and dry shale. The experimental results show that the NMR porosity obtained through this method is in good agreement with the weight porosity, and the influence of background signal from hydrogen-containing matrix components in shale is eliminated.