Heterogeneity analysis of shale reservoir based on multi-stage pumping data

Heterogeneity analysis of conventional data, such as geophysical log data, has been still limited to the application of near-wellbore zone, which makes it difficult to optimize the hydraulic fracturing design and may render suboptimal performance. However, the fluctuation of multi-stage pumping data, manifesting nonlinear behavior of physical properties with shale reservoir during hydraulic fractures propagation stage, is usually ignored. In this study, the empirical mode decomposition technique (EMDT) was introduced and applied to the multi-stage pumping data to determine the respective Intrinsic Mode Functions (IMF). By using a relationship between the IMF number and its mean wavenumber, the heterogeneity index associated with far-wellbore shale reservoir was determined. The results indicate that the heterogeneity index from multi-stage pumping data is good coincided with the effective stimulation reservoir volume (ESRV) obtained from micro-seismic events. Not only that, but it also reveals that there is a strong correlation of heterogeneity index, IMF number, ESRV, and degree of heterogeneity within shale reservoir. This work has demonstrated that heterogeneity index analysis combined with EMDT has been significantly important and essential to quantify the degree of heterogeneity within far-wellbore shale reservoir from multi-stage pumping data, which contributes to optimizing the hydraulic fracturing design and improving good optimal performance.