A modified Stolt migration imaging algorithm for large nonuniform single borehole radar surveys

In this paper, the formulation of Stolt migration is modified for impulse borehole radar imaging in large nonuniform subsurface scenarios. By applying the nonuniform fast Fourier transform to the acquisition of frequency-wavenumber spectrum, the efficiency of Stolt migration for nonuniform surveys is improved. The selection of approximation parameters is discussed to make a tradeoff between approximation error and computational cost. The improved Stolt migration technique is compared with conventional back projection method and Kirchhoff migration method on synthetic data and validated by single borehole radar experiment in subsurface scenario. The results show that the developed Stolt migration is superior to the conventional methods in cross-range resolution, computational cost, and the ability to reconstruct locations and shapes of targets.