Characterization of Hydraulic Fractures With Triaxial Electromagnetic Induction and Sector Coil Rotation Measurement

The characterization of hydraulic fractures is crucial for fracturing evaluation and strategy optimization. Low-frequency electromagnetic triaxial induction measurement is a promising candidate in hydraulic fracture characterization. However, it is difficult to accurately monitor fracture shape, orientation, and the multistage fracture network distribution. A novel method that combines triaxial induction measurement with sector-shaped coils axial rotation measurement (TIM-SCARM) is proposed to characterize hydraulic fractures. It is implemented by using the finite element method with transition boundary conditions (FEM-TBCs), which approximates the thin fracture as a surface to enhance the computational efficiency. The study focuses on quantitative analysis of conductivity, cross-sectional shape, half-length, and orientation of hydraulic fractures to assess their effects on specific configurations of the TIM-SCARM. Furthermore, the correlations between multicomponent signals and fracture characteristics are investigated. Numerical results indicate that the coaxial component signal in SCARM can distinguish the cross-sectional shape and orientation. The cross-polarized component signals provide important features of tilted fractures, and the 3-D signal obtained by instrument rotation could determine the spatial distribution of fracture networks. Therefore, measurements that integrate the multicomponent signals and axial information improve fracture geometry evaluation.