Anti-clamping cement injecting pipe string for downhole casing patching, and casing patching method

Abstract

The invention discloses an anti-clamping cement injecting pipe string for downhole casing patching, and a casing patching method. An upper replacement device is placed in a patching pipe conveying pipe string, and the upper replacement device and the patching pipe conveying pipe string are matched to be sealed; a lower replacement device is placed on the lower portion of a patching pipe, the lowerreplacement device and the patching pipe are matched to be sealed, and the lower replacement device is connected to the patching pipe through shearing pins; the upper portion of a separation joint isconnected to the lower portion of the patching pipe conveying pipe string; the inner diameter of a through hole in the lower replacement device is smaller than that of a plug on the lower portion ofthe upper replacement device; the upper portion of an unidirectional sealing device is connected into the lower portion of the separation joint; after the unidirectional sealing device is placed intothe patching pipe from the upper portion of the patching pipe, the exterior of the lower portion of the separation joint is connected with the upper portion of the patching pipe; the unidirectional sealing device and the patching pipe are matched to achieve unidirectional sealing; and a liquid flow can be pushed downwards from an annular channel between the unidirectional sealing device and the patching pipe, the patching pipe conveying pipe string and the patching pipe are separated, cement slurry is driven to a well to patch a casing, and after patching is finished, the patching pipe conveying pipe string is not clamped by cement.

Description

technical field [0001] The invention is a pipe string used in wellbore repair technology in oilfields. It is a pipe string for preventing the pipe string conveying the subsidy pipe from being stuck by cement slurry and cannot be pulled out when casing subsidy is performed in a well with damaged casing. Specifically, it is a downhole casing subsidy prevention Card injection gray pipe string and casing subsidy method. Background technique [0002] After the casing of the oil and water well is damaged, it is necessary to use the casing subsidy method to subsidize the casing rupture to prevent casing leakage. Pour cement slurry between the casing and subsidized pipe. After the cement slurry is solidified, the casing and subsidized pipe are consolidated into one, and then the pipe string for conveying subsidized pipe is separated from the subsidized pipe, and the pipe string for conveying subsidized pipe is lifted out. The wellbore, so as to repair the rupture of the casing, so ...

AI Technical Summary

Problems solved by technology

According to the above, the current tools, construction steps, and pipe strings are designed and matched according to the principle of pouring cement slurry first, and then separating the pipe string for conveying the subsidy pipe from the subsidy pipe, thus forming the current construction technology. The accident that the pipe column of the subsidy pipe was stuck by the cement slurry caused the pipe string conveying the subsidy pipe to be unable to separate from the subsidy pipe, and accident handling work was required, resulting in significant economic losses

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