Rotatable fishing socket for underground coal mine and fishing method of rotatable fishing socket

Abstract

The invention discloses a rotatable fishing socket for an underground coal mine and a fishing method of rotatable fishing socket. The fishing socket comprises an upper joint, a barrel body, a guidingshoe, a control ring and a slip, wherein one end of the barrel body is in screwed connection with the upper joint, the other end of the barrel body is in screwed connection with the guiding shoe, a barrel internal thread is arranged in the middle of the barrel body, a slip boss located in a control ring is arranged on one end of the slip, at least one annular key groove is formed inside the innercircumference of the control ring to control the position of the slip in a fishing process, a slip external thread is arranged on the outer edge of the other end of the slip and matches with the barrel internal thread of the barrel body, the slip internal thread is arranged on the inner edge of the other end of the slip and used for grabbing a fishing drilling tool, and a gap is reserved between the slip external thread and the barrel internal thread. Therefore, the rotatable fishing socket is simple in structure, convenient to operate and wide in application, the position of the slip is limited, clamping and loosening operation of the slip on a drilling tool is achieved, the working principle of an existing fishing socket is changed through rotary pulling, and the rotatable fishing socketcan be used for near-horizontal well drilling.

Description

Technical field [0001] The invention relates to the technical field of underground fishing in coal mines, in particular to a rotatable overshot used in underground coal mines and a fishing method thereof. Background technique [0002] Due to the poor stability of the coal seam and the high gas content in the coal seam, stuck and buried drills often cause drill tool breakage accidents in the process of underground coal mine drilling. At present, the drilling tools in underground coal mines mostly use fishing male cones and fishing female cones. , Both of them are made by rotating new threads on the drilling tool, and the drilling tools are locked and lifted by the threads. The threads made are generally shallow and not tightly fitted, and the pulling force that can withstand is limited, so for drilling Salvaging complex drilling tools often ends in failure. Salvaging the accidents of broken drill holes in coal mines has always been an important research topic. [0003] Overshot ha...

AI Technical Summary

Problems solved by technology

The gas content in underground coal mine drilling is high, and the risk of drill sticking and burial is high. In addition, coal seam drilling is mostly near-horizontal drilling. The existing overshot has the following defects in the application of underground coal mines:

[0005] 1. When the overshot is lowered, the drilling tool can only be pushed into the slips and cannot be rotated: the current fixing mechanism of the overshot slips and the cylinder body is to fix the long key of the control ring between the slips and the outer cylinder during installation. , when the overshot is lowered, the long key of the control ring will withdraw from the slip keyway. At this time, if the overshot is turned, the shift of the long key cannot continue to align with the keyway on the slip. Drilling, because the long key resists the slips, the slips are always in a loose state, unable to bite the drill tool, and the overshot fails

In addition, if it is not possible to turn and buckle during the salvage process, it is impossible to effectively grind the reduced-diameter borehole. In the stratum with collapsed holes, the annular space is large, and it is difficult to effectively bite the drill tool.

[0006] 2. During the lifting process of biting the drilling tool, it cannot be rotated and lifted, but can only be pulled out forcefully to release the jamming. The success rate of unjamming is low when the stuck drill and buried drill are salvaged: if the drilling tool is bitten and pulled out by rotation, the control The long key of the ring drives the slips to rotate together in the slip groove. Because the contact surface between the slips and the long key of the control ring is small, the slips are likely to burst due to the uneven force on the slips along the strip. Therefore, the overshot is used to bite the slips. After the drill tool can only be pulled out forcefully to release the card

[0007] 3. When fishing drilling tools in near-horizontal wells underground in coal mines, due to the lack of gravity of the drill string, the overshot cannot be lowered with full weight, and the success rate of releasing the drilling tools is low. The existing overshot has great limitations

[0008] 4. The installation and assembly are complicated. If the salvage is unsuccessful at one time, the overshot can only be released by the drilling tool, and the overshot needs to be disassembled again, and the long key of the control ring is reinstalled into the slip keyway, and it is a waste of manpower and time to drill again.

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