Constant pressure tailpipe, water injection string and method for liquid injection using the water injection string

CN122169712APending Publication Date: 2026-06-09PETROCHINA CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
PETROCHINA CO LTD
Filing Date
2024-12-06
Publication Date
2026-06-09

AI Technical Summary

Technical Problem

Conventional water injection tubing is easily contaminated by dirt such as oil, dead wax, and mud when it is lowered into the wellbore, making it difficult to lower the instrument. Backwashing the well can easily cause the ball seat to become blocked, making the operation difficult and posing safety hazards.

Method used

Design a constant pressure tailpipe, comprising a pipe shell, a push rod, and a one-way flow device. One-way flow is achieved by switching the state of the push rod, preventing dirt from entering the tubing string and enabling effective fluid flow during backwashing.

Benefits of technology

It effectively prevents dirt from entering the tubing from the wellbore, simplifies the operation process, improves the success rate of water injection tubing installation and backwashing efficiency, and reduces safety risks and labor intensity.

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    Figure CN122169712A_ABST
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Abstract

This invention relates to the field of oil extraction technology, and discloses a constant-pressure tailpipe, a water injection string, and a method for injecting fluid using the water injection string. The constant-pressure tailpipe includes a casing, a push rod, and a one-way flow device. The casing has an internal flow channel for fluid passage, and a screen is provided at the bottom of the casing. The push rod is located inside the casing and has a first state where it blocks the flow channel to prevent fluid from flowing into the casing through the screen, and a second state where it opens the flow channel to allow fluid to flow into the casing. The one-way flow device is located inside the casing and above the push rod. When the push rod is in the first state, it supports the one-way flow device to place it in a first position; when the push rod is in the second state, it disengages from the one-way flow device, and the one-way flow device is in the second position. This constant-pressure tailpipe enables one-way flow, thereby preventing contaminants such as oil, dead wax, and mud from entering the casing during the string's installation.
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