A permanent magnet short joint

Abstract

The invention provides a permanent-magnet pipe nipple. The permanent-magnet pipe nipple is characterized in that a plurality of first spiral grooves are formed in the surface of a non-magnetic drill collar; rare-earth permanent magnets are placed in the first spiral grooves; magnetic-conducting iron cores are used for connecting adjacent rare-earth permanent magnets; spiral groove rubber is used for fixing the rare-earth permanent magnets and the magnetic-conducting iron cores; the rare-earth permanent magnets are serially connected through the magnetic-conducting iron cores and arranged on the non-magnetic drill collar in a spiral line manner, and adjacent permanent-magnet pipe nipples with the same polarity are prevented from repelling each other. By the arrangement, the permanent-magnet pipe nipple has the advantages that the dispersed rare-earth permanent magnets are serially connected by the magnetic-conducting iron cores, the magnetic potential of a closed loop is increased effectively, and the range of the magnetic field radiated by the rare-earth permanent magnets is wide; the rare-earth permanent magnets are placed in the spiral grooves, the spiral lines formed by the serial connection of the rare-earth permanent magnets can be parallelly connected effectively, loop magnetic flux is enhanced to allow the magnetic-field components of the single spiral line to superimpose so as to enhance the magnetic field intensity of a far position, and the magnetic performance of the permanent-magnet pipe nipple is increased.

Description

technical field [0001] The invention belongs to the technical field of drilling equipment, in particular to a permanent magnet short joint. Background technique [0002] my country is rich in coalbed methane resources and underground mineral resources. With the development of coal gas beds, more and more technologies are applied to the mining process. Among them, the two-well connection technology is one of the main technologies. During the connection process, when the rotating permanent magnet sub in the main borehole enters the detection range of the detection tube in the pre-connected cave well, the magnetic probe collects the magnetic field signal of the permanent magnet sub Intensity, through the software to calculate the distance between two horizontal directional docking wells and the current position of the drill bit, so as to realize the docking of the two wells. [0003] At present, there are the following types of permanent magnet sub-joints: the first type of pe...

AI Technical Summary

Problems solved by technology

[0006] Aiming at the problems existing in the prior art, the embodiment of the present invention provides a permanent magnet pup joint, which is used to solve the mutual repulsion between the ends of the same polarity of the adjacent permanent magnets in the permanent magnet pup joint in the prior art, and non-magnetic drilling The technical problem that the two horizontal directional wells cannot be accurately docked due to the weak magnetic field strength in the axial direction

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