METHOD AND DRILLING ASSEMBLY FOR CASED DRILLING

摘要

the invention concerns a method and a bohranordnung to verrohrten drillthe ground at least in a upper part of a bohrrohr hole 12 to be introduced and deposits within the bohrrohrs 12 by means of a spinning angetriebenen drilling and borehole abgebohrt removed.according to the invention it is provided that in a top area of the bohrrohres 12 in a negative pressure by means of an annular bohrrohr unterdruckeinheit 20 is generatedwith a field with negative pressure in the bohrrohr 12 is formed, and the negative pressure so that air will be recruited from above in the unterdruckbereich circular flows.