核磁共振敏感参数在低对比度油层识别中的应用

Application of Sensitive NMR Parameters in Oil-water Identification of Low-contrast Reservoirs

鄂尔多斯盆地姬塬地区延长组长×储层为低对比度油层,油水关系复杂,矿化度较低且变化大,发育大量高电阻率水层,常规油水识别难,解释符合率较低。通过储层特征与油水识别难点分析,在岩石物理实验的基础上,明确核磁共振T2谱形态特征的主要影响因素,提出了基于核磁共振T2谱的半幅点偏移量、离散度、右翼展幅、拖尾面积等多个反映流体性质的敏感参数。综合应用敏感参数加权组合,建立了基于核磁共振敏感参数的油水定量识别标准。应用于20口井,解释符合率明显提升,形成了阵列感应+核磁共振测井系列,解决了低对比度油层的识别问题,取得良好地质应用效果。

The low-contrast Chang×reservoir in the Jiyuan area,the Ordos Basin,has complex oil-water relations,low and variable water salinity and many high-resistivity water layers.It is difficult to identify OWC and the logging interpretation coincidence rate is low.In this paper,based on petrophysics experiments,the influencing factors on NMR T 2 spectrum morphology are identified,and then sensitive NMR parameters for fluid properties are proposed,such as half-amplitude point offset,dispersion,right wring amplitude and tailing area of NMR T 2 Spectra.Finally a quantitative oil-water identification standard is established based on the sensitive parameters.Application in 20 wells proved the coincidence rate improved obviously.It is useful to identify oil layers in low-contrast reservoirs.The geological application is achievable.