RE: Pearl and A359 Mar 2023 03:51
Bamps, dont want to be a "know it all " but as a D Driller from another life, drilling mud is used to lube the drilling head and harden the drill hole so as to stop it caving in , if the mud recipe is correct it can reenforce the hole so that it is almost as hard as the surrounding rock .
Re the missing core, they should have used a split tube if they had any inkling that core recovery was going to be tricky, that method has an almost 100% recovery record, what they can now do is wedge off the old hole above the offending missing core and redrill using a split tube which should do the job.