用测井双TW观测数据识别储层流体性质

储层中油、气、水具有不同的核磁共振弛豫响应特征，采用不同的等待时间进行测量，核磁共振测井响应上可反映出流体性质的差异，为此，核磁共振测井设计了双TW观测方式。文章简单介绍了核磁共振测井中流体的弛豫机理及其双TW资料采集过程，详细讨论了对核磁共振双TW测井资料进行正确解析的定性分析方法--TDA差谱分析方法，并基于含油饱和度与T₂形态变化关系的实验依据，针对不同等待时间的可动流体之差提出了流体识别的定量分析方法--FLAG指示法，根据试油结果构建了FLAG指数的经验关系图版,最后结合几个实例对上述方法进行了详细地分析和应用，实现了储层中流体性质的定性识别和定量解释。应用结果表明,核磁共振双TW观测方式及其分析方法是行之有效的，可作为直接发现油气层的一种有效方法。

IDENTIFICATION OF FLUID PROPERTY WITH NMR DUAL-TW WELL LOGGING DATA

Oil, gas and water in reservoirs show different nuclear magnetic resonance (NMR) relaxation properties, and the differences of fluid properties can be reflected in NMR well logging responses when different waiting times (TW) are used in measurement, so dual-TW observation method is designed for NMR well logging. This paper briefly introduces the fluid relaxation mechanism of NMR well logging and the data acquisition process of dual-TW logging, and discusses in detail the different spectrum methods (DSM) for time domain analysis (TDA), which can be used to perform qualitative analysis of NMR dual-TW well logging data. Based on the relationship between oil saturation and T2 shape obtained in experiments, FLAC index method, a quantitative analysis method for fluid identification, is proposed according to the difference between mobile fluids at different waiting times (TW) and an empirical relation chart of FLAG index is established based on formation testing results. This method has been applied to several cases, and qualitative identification and quantitative interpretation of reservoir fluid properties are realized. Application shows that NMR dual-TW observation method and the analytical method are feasible and can be used to effectively and directly detect oil and gas.