A gas injection well downhole tubing leak monitoring system and method

CN120867733BActive Publication Date: 2026-06-30PETROCHINA CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
PETROCHINA CO LTD
Filing Date
2024-04-30
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

Existing technologies cannot perform real-time and efficient integrity monitoring of downhole tubing in gas injection wells. Especially under the action of corrosive high-pressure fluids, tubing is prone to damage or leakage. Existing methods can only perform local detection and cannot cover the entire wellbore.

Method used

By employing fiber optic sensing technology, optical fibers are installed inside the oil pipe, combined with distributed optical fiber sensors (DAS). After gas is injected into the oil pipe to generate a pressure difference, amplitude and phase noise data are collected. Spectrum analysis is then used to determine the location and type of leaks, enabling real-time monitoring of the oil pipe's integrity.

Benefits of technology

It enables automatic, real-time monitoring of downhole tubing, accurately pinpointing the location and type of leaks, improving monitoring accuracy and efficiency, and ensuring wellbore safety.

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Abstract

This invention discloses a downhole tubing leakage monitoring system and method for gas injection wells. The system employs an optical fiber deployment method, lowering the fiber to a designated location within the tubing. Gas is injected into the tubing until a pressure differential is achieved, then injection is stopped, and the tubing valve is closed. After a period of settling, the system collects the amplitude and phase fundamental noise at this stable state. The system continues to wait until the well pressure reaches a designated value, then the casing valve is opened, and corresponding acoustic data is collected. If the amplitude data cannot locate the suspected leak, the casing valve is closed, and the process is repeated, collecting acoustic data at various pressures until the amplitude data can distinguish the suspected leak or the pressure can no longer be increased to locate it. The data collected at the highest pressure is then subjected to spectral analysis. The leak location and type are determined based on the frequency range of the amplitude signal strength and phase. Therefore, this method determines the leak location and type by monitoring and analyzing the collected data.
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