基于三维有限元的水力压裂电磁监测方法数值模拟OA

To enable effective evaluation of hydraulic fracturing fracture geometry under different burial depths and scales,this study conducts numerical simulations of three electromagnetic monitoring approaches in hydraulic fracturing scenarios.A three-dimensional finite element method(3D FEM)is employed to construct electromagnetic response models of multi-fracture hydraulic fracturing in horizontal wells,and the accuracy and validity of the numerical algorithm are verified through comparisons with benchmark models.On this basis,the electromagnetic response characteristics and sensitivity patterns of controlled-source electromagnetic,surface-to-borehole electromagnetic,and cross-well electromagnetic methods are systematically investigated and analyzed under varying source operating frequencies,fracture spacing,fracture geometries,proppant electrical conductivity,and fracture scale parameters.The results indicate that the sensitive field components are strongly dependent on fracture orientation,with the Ey component of the controlled-source electromagnetic and surface-to-borehole electromagnetic methods and the Ezz component of the cross-well electromagnetic method being most sensitive to fracture geometric parameters.Within the analyzed frequency range,an operating frequency of approximately 10 Hz achieves an optimal balance between signal strength and investigation depth and is suitable for far-field fracture monitoring.When the electrical conductivity of hydraulic fracturing proppants is approximately 1 000 S/m,the distinguishability of fracture-related electromagnetic responses is significantly enhanced.The controlled-source electromagnetic method is effective for characterizing shallow,large-scale hydraulic fractures(burial depth less than 500 m),the cross-well electromagnetic method is more suitable for monitoring deep,large-scale hydraulic fractures,whereas the surface-to-borehole electromagnetic method provides complementary capabilities for detecting small-scale fractures.Overall,the three electromagnetic monitoring approaches exhibit strong complementarity across different burial depths and fracture scales,and their combined application enables the acquisition of one-dimensional and two-dimensional electromagnetic responses of both shallow and deep hydraulic fracturing,providing a theoretical basis and technical reference for fracture geometry evaluation and monitoring strategy optimization.