A method and device for active heating distributed fiber optic temperature monitoring for low-flow water injection in horizontal wells.

CN122084149AActive Publication Date: 2026-05-26SANYA MARINE OIL & GAS RESEARCH INSTITUTE NORTHEAST PETROLEUM UNIVERSITY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-04-24
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

In horizontal well water injection monitoring, existing distributed fiber optic passive temperature measurement technology has limitations due to the small temperature difference between the injected fluid and the wellbore/formation, weak thermal disturbance in the wellbore, and low background flow velocity. This results in inconspicuous temperature anomalies along the flow path, making it difficult to accurately identify background flow and injection flow, uneven water distribution, and short-circuit crossflow.

Method used

An active heating distributed fiber optic temperature monitoring method is adopted. By applying controllable thermal excitation inside the wellbore and combining it with distributed temperature response signals, the correspondence between temperature response characteristics and wellbore background flow, water injection flow and its flow distribution is established, so as to realize the identification and quantitative identification of horizontal well background flow and water injection status.

Benefits of technology

It improves the flow identification capability under conditions of weak temperature difference and low flow rate, and can continuously identify uneven water distribution, local water injection anomalies and short-circuit crossflow. It provides a rapid quantitative calibration method. The device has a clear structure and convenient operating condition control, and has good feasibility and engineering promotion value.

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Abstract

This invention relates to an active heating distributed fiber optic temperature monitoring method and device for low-flow-rate water injection in horizontal wells. The device includes: a distributed fiber optic temperature measurement host, a simulated horizontal wellbore under test, an active heating unit and armored optical cable deployed along the pipeline, a water pump and pipeline circulation unit, an injection pipe, and a data processing computer. The method includes: establishing a steady-state temperature baseline; applying heating pulses or steps to the active heating unit at preset power and duration; acquiring the friction-temperature response ΔT(x,t) using a distributed fiber optic temperature measurement system (DTS); and quantitatively characterizing the background flow intensity and water injection distribution based on a one-dimensional convection-diffusion-heat transfer model and Nusselt correlation inversion to obtain the local convection heat transfer coefficient and flow rate. This invention introduces controllable thermal excitation through active heating, improving the identifiability under conditions of weak temperature difference and low flow velocity, and can be used in fields such as horizontal well water injection profile monitoring, identification of weak flow in complex wellbores, and downhole distributed dynamic monitoring.
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