Magnetotelluric extremum boundary inversion based on different stabilizers and its application in a high radioactive waste repository site selection

摘要

Geophysical inversion under different stabilizers has different descriptions of the target body boundary, especially in complex geological structures. In this paper, we present an extremum boundary inversion algorithm based on different stabilizers for electrical interface recognition. Firstly, we use the smoothest and minimum-support stabilizing functional to study the applicability of adaptive regularization inversion algorithm. Then, an electrical interface recognition method based on different stabilizers is developed by introducing extremum boundary inversion algorithm. The testing shows that the adaptive regularization inversion method does work for different stabilizers and has a low dependence on the initial models. The ratio of the smooth and focusing upper and lower boundaries obtained using the extremum boundary inversion algorithm can clearly demarcate electrical interfaces. We apply the inversion algorithm to the magnetotelluric (MT) data collected from a preselected area of a high-level-waste clay-rock repository site in the Tamusu area. We recognized regional structures with smooth inversion and the local details with focusing inversion and determined the thickness of the target layer combined with the geological and drilling information, which meets the requirement for the site of the high-level waste clay-rock repository.