Double-plug piping method of heavy-caliber gas exhaust hole working sleeve

Abstract

The invention provides a double-plug piping method of a heavy-caliber gas exhaust hole working sleeve. The method comprises the following steps of: preparing a buoyancy plug and a buoyancy valve; piping by a suspending method; welding the buoyancy plug; piping by a buoyancy plug piping method; welding the buoyancy valve; filling high-pressure gas in the region between the buoyancy plug and the buoyancy valve; continuously piping to the hole bottom by the buoyancy plug piping method; drilling and breaking the buoyancy valve to release the high-pressure gas; and piercing the buoyancy valve and the buoyancy plug; and cementing wells. According to the invention, the problem that the transverse pressure of exterior mud to a hollow pipe is too large during the buoyancy plug piping construction is solved, the danger of instability of a working sleeve is reduced, the buoyancy upper limit is increased in comparison with the conventional buoyancy plug method, and a drilling machine with less load capacity can be used for piping under the same condition.

Description

technical field [0001] The invention belongs to the technical field of drilling construction for coal gas extraction and drainage, and in particular relates to a method for lowering a working sleeve of a large-caliber gas extraction and drainage hole with double plugs. Background technique [0002] At present, high-gas mines usually use gas drainage holes to drain underground gas to the ground and make use of it. This gas control method has low comprehensive cost and good effect, so it has been more and more widely used. [0003] After the gas drainage hole is drilled to the target hole depth and reamed, the working casing needs to be lowered to keep the drilling stable, prevent groundwater from seeping into the working face, and ensure gas extraction rate and ventilation. [0004] As the depth and diameter of the gas extraction and drainage holes increase, the total mass of the working casing becomes larger and larger. Therefore, during the running process, a buoyancy plug ...

AI Technical Summary

Problems solved by technology

[0015] In order to solve the problems of too long empty pipe, excessive lateral pressure of the external mud on the empty pipe and too small load capacity of the drilling rig in the conventional buoyancy plug down pipe construction, the present invention provides a method of using buoyancy plug and buoyancy valve to enter the working casing The working casing running method of providing buoyancy and filling high-pressure air between the buoyancy plug and the buoyancy valve

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