Abstract:

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.

Key words: low-field NMR, 2D NMR, shale, nano-scale pore, fluid types and content