Meikuang Anquan (Jun 2023)
Gas reverse circulation drilling technology for large-diameter DTH hammer
Abstract
Large diameter DTH hammer is a drilling tool which has been proved by a lot of engineering practice and can improve the construction efficiency of large diameter drilling on mine surface. However, after drilling into the aquifer, the penetration rate of large diameter drill hammer is often slow or even impossible. Therefore, a large-diameter drilling method of DTH hammer gas reverse circulation is proposed, which is characterized by pneumatic slag drainage in reverse circulation mode and residual gas drainage in positive circulation mode. The basic principle of large-diameter DTH hammer gas reverse circulation drilling technology is analyzed, and the bottom hole pressure balance condition of gas double upper return passage is established. The composition of large-diameter DTH hammer gas reverse circulation drilling system is introduced, and the field test is completed relying on the mine surface large diameter drilling project. The results show that, under the condition of formation water discharge, the expected effect of reverse circulation slagging and drainage can be achieved by controlling the pressure of the annular air column with throttling. The drilling efficiency is high, and the maximum well depth is 668 m, which can be widely applied to the construction of mine surface rescue wells and various kinds of mining large-diameter drilling projects.
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