Nonlinear inversion of surface nuclear magnetic resonance over electrically conductive medium
导电性影响的地面核磁共振反演

Electrical conductivity impacts the inversion of the data of surface nuclear magnetic resonance (NMR) sounding method. When the effect of electrical conductivity cannot be ignored, the square of the induced voltage of surface NMR can be expressed as a quadratic form involving water content as variables. Further analysis shows that the derivative of the square of the surface NMR voltage with respect to water content is of closed form. This makes nonlinear inversion of surface NMR data possible, and can speed up the inversion significantly. Numerical results show that the water content distribution resulted from nonlinear inversion agrees very well with the true model of both free space and electrically conductive medium.