Analytical solution of induction logging electromagnetic field in fracture development formation based on perturbation method
Inspired by the electromagnetic perturbation method,we regard the influence of fractures as the per-turbation of electromagnetic fields of undisturbed formations.Based on the solution of the Helmholtz equation in radial layered media,we propose an analytical solution of induction logging electromagnetic fields applicable to any fracture occurrence,any well diameter,and any mud resistivity after studying the analytical solution of the electromagnetic field of infinitesimal antenna vibrator outside the column.Relying on this,we take the HDIL 1515 EA/MA array induction logging tool commonly used in China as an example to calculate the in-duced electromotive forces of receiver coils in four kinds of fractured formation models and draw the(theoretical charts of)apparent conductivity curves.The research shows that there is not necessarily a spike in the array in-duced apparent conductivity curve in the fracture development formation.At the same time,under the condition of oil-based mud,the apparent conductivity curves of the seven sub-arrays in the formations where microfrac-tures are densely developed show amplitude differences,and they can be used to identify the microfracture de-velopment section for the different characteristics compared with mud invasion formations.
induction loggingfractured formationelectromagnetic field perturbation methoddyadic Green's function
万方数据
维普
