Stepwise deep burning by constructing underground vaults - for further coaxial drilling enables increase of max. boring depth for mineral and other exploitation

摘要

This is a deep-boring method for the exploitation of mineral resources and geothermal energy at depths not normally possible. A deeper working depth is reached in stages. If, after exploitation by normal methods, a greater depth is needed for further work at least two parallel boreholes of large dia. (D) are sunk as shown in the diagram, and lined with the usual type of steel casing, down to an economic depth. At this depth, a vault is made to serve as a new level to start further boring by personnel and equipment (including power supply) lowered through the first boreholes. Further boreholes are sunk coaxially with the first ones, for constructing the next vault. At least two parallel boreholes are made, for ventilation. Further vaults are made in a similar way, down to a planned depth. In the diagram, derricks (Bohrturme) and boreholes (Bohrungen) are indicated. USE/ADVANTAGE - Max. boring depth is normally limited by the strength of the steel casing. The proposed technique enables max. boring depth to be increased to allow deeper exploitation.