Borehole tube string installation - using barrier discs for temporary retention of float fillings

摘要

Wells and boreholes which are at least partly filled with a liquid, e.g. the drainage boreholes in open cast mining operations, are equipped with a string of sectional dewatering tubes. At least a part of the sections is filled with floats which are retained during the lowering operation by barriers. After completion of the outfit, the barriers are removed so that the floats, preferably hollow plastic elements, can rise and be recovered. This reduces the load on the lifting tackle during the lowering operations. The floats are inexpensive and are recovered.