Orifice Sealing Device for Large Diameter DTH Hammer and Its Reverse Circulation Construction Technology

Abstract

An orifice sealing device for large-diameter down-the-hole hammers and its reverse circulation construction process are proposed in view of the problems existing in the current hole bottom sealing structure of large-diameter down-the-hole hammers. When the hole bottom sealing mechanism cannot fully meet the needs of establishing reverse circulation, That is, when a large amount of gas returns from the annular gap formed by the large-diameter DTH hammer and the drilled hole, under the action of the orifice sealing device, the large annular gap formed by the drilled hole and the double-walled drill pipe is a closed and limited space. When the gas pressure in this space reaches a certain level, the compressed air at the bottom of the hole is forced into the large-diameter DTH hammer slag discharge channel and discharged to the mud pool along the inner pipe of the double-wall drill pipe, thereby re-establishing the reverse circulation channel. The requirements of the hole bottom sealing structure are greatly reduced, that is, the gap between the hole bottom sealing structure and the drilling hole can be appropriately increased, so it can reduce the design difficulty of the hole bottom sealing structure, improve the ability of the reverse circulation DTH hammer to deal with complex situations in the hole, and achieve the purpose of safe and efficient drilling. .

Description

technical field [0001] The invention relates to the technical field of drilling, in particular to an orifice sealing device for a large-diameter down-the-hole hammer applied to the high-efficiency drilling technology of an air down-the-hole hammer and a reverse circulation construction process thereof. Background technique [0002] At present, during the construction of large-diameter drilling (≥Ф550mm) rock sections, the method of "small drilling and large drilling expansion" is usually adopted, mainly completed by reaming roller cone bits and positive mud circulation technology. The construction of large-diameter drilling holes on the ground for mine rescue requires "fast", and rapid drilling in the rock section is an extremely important link to achieve this goal. Due to the low mechanical penetration rate of the roller cone reaming bit, it is difficult to meet the mine emergency rescue drilling requirements. Hole construction requirements. Air down-the-hole hammer breaks...

AI Technical Summary

Problems solved by technology

The above-mentioned large-diameter reverse circulation down-the-hole hammer promotes the formation of the main structure of the hole bottom reverse circulation. The main structure is set on the bottom hole drilling tool body. The diameter of the drilled hole should be small, and the gap area between the outer diameter of the sealing structure and the drilled hole wall is getting larger and larger; and there is a certain expansion rate of the drilled hole diameter during the drilling process of the drill bit, so the amount of compressed gas from the gap becomes larger, which may affect Reverse circulation slagging effect, severe cases can not even form reverse circulation

Images