Assessment of mesh quality for fully unstructured 3D mesh generated with Geode

Hi all, I am trying to model a deviated deep borehole heat exchanger using the mesh generator Geode. I am wondering how I can assess the quality of the 3D unstructured mesh. And wether I can account for the ideal element size close to the BHE nodes as in the 2D layered approach. Best regards Dominik  

I can generate a mesh with Geode without any problems, but if I change the "Global edge size at polyline" setting to match the ideal element size depending on my borehole radius, I suddenly get the error "self intersection was detected" . I have not changed anything else. What could be the problem? The problem does not occur when I mesh only the borepath and the bonding box (without the geological layers as surfaces in the supermesh).