2DNMR在泥页岩物性及流体评价中的应用探讨

纳米级孔隙、非达西渗流、自生自储是泥页岩油气层的主要特征,常规NMR技术难以检测到T2弛豫时间短于0.1 ms的纳米级孔隙,并难以准确评价泥页岩储层中的孔隙流体性质与含量.为了解决以上问题,以济阳坳陷下第三系沙河街组泥页岩油气主要勘探层段为研究对象,采用高分辨率2D NMR技术对采自3口井的11块泥页岩样品分别进行1D、2D NMR分析.结果表明,T2谱能够检测到泥页岩中的全部孔隙量;D-T2谱能够准确评价孔隙流体类型与含量,且核磁含油饱和度与石油的产液量、岩石热解的液态烃量具有可对比性.该项研究对精细评价泥页岩油气储层具有十分重要的意义,对进一步发展高分辨率2D NMR技术具有一定的促进作用.

Evaluating Shale Porosity and Oil Content with 2D NMR

Compared with conventional reservoir, shale reservoir is characterized by nanoscale pores, non-Darcy flow and self-generating/self-preserving properties. However, it is difficult to probe components in nanoscale pores with T₂ relaxation time less than 0.1 ms, and to evaluate fluid types and content in shale reservoir with conventional NMR technology. In this study, high resolution 2D NMR technology was adopted to evaluate eleven shale samples collected from three wells in Shahejie formation of Jiyang Depression. By comparing with the data from formation testing and rock pyrolysis, it was confirmed that the T₂spectrum measured with 2D NMR could reflect the properties of nanoscale pores, and D-T₂ spectrum could be used to evaluate fluid types and content. The work suggested that high resolution 2D NMR technology is useful in unconventional resource exploration of shale.