Acoustic Logging Guided-Wave Speed for Wellbore Leak Localization
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Solution Overview
Problem
Identifying the source of pressure communication between well tubing-casing and casing-casing annuli in oil and gas wells is challenging due to the presence of guided-wave noise, which contaminates direct wave signals and makes leak detection difficult.
Innovation Solution
An acoustic logging tool with two or more hydrophones is used to measure the speed of guided-wave noise, which is related to the acoustic velocity of the wellbore fluid. This allows for the discernment of the wellbore fluid phase and the identification of fluid phase interfaces, enabling more accurate leak localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If guided-wave noise is removed from acoustic data, then direct wave signal quality is improved, but measurement precision deteriorates because guided-wave speed contains useful fluid phase information
Solution Approach 1:
The patent converts the harmful guided-wave noise into a beneficial measurement tool by recognizing that the noise contains useful information about wellbore fluid phase. Instead of removing the guided waves, the system measures their speed to determine fluid phase (gas, liquid, or solid), thereby transforming a contaminant into a source of valuable diagnostic information.
Solution Approach 2:
The patent introduces an intermediary processing step that separates the direct wave signal from the guided-wave noise in the frequency domain. By measuring the speed of guided waves at different frequencies and comparing them to reference speeds, the system can identify fluid phase interfaces while preserving both the direct wave signals for leak detection and the guided-wave information for fluid phase characterization.
2Loss of information
If guided-wave noise is present in acoustic data, then fluid phase information is preserved, but leak detection accuracy deteriorates due to signal contamination
Solution Approach 1:
The patent segments the acoustic signal into different frequency components, separating direct waves from guided-wave noise. By processing these segments differently—using direct waves for leak detection and guided waves for fluid phase identification—the system achieves both leak detection accuracy and fluid phase information preservation simultaneously.
Solution Approach 2:
The patent applies partial filtering that removes only the problematic frequency components of guided-wave noise while preserving the useful fluid phase information. Rather than complete removal or complete retention, the system selectively processes different frequency ranges to optimize both leak detection and fluid phase characterization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively differentiates between guided-wave noise and direct wave signals, allowing for precise identification of leaks and fluid phases within the wellbore, thereby improving the accuracy of pressure communication source identification.
Implementation Method 1
guided-wave noise that propagates along the borehole that is not from the noise source is also recorded by the hydrophones
Implementation Method 2
The guided-wave speed is related to the acoustic velocity of a fluid within the wellbore
Implementation Method 3
direct waves that propagate directly from a noise source (i.e., a leak) to one or more hydrophones are recorded
Data Source
AI summary
A method for identifying guided waves in a measurement set. The method may comprise disposing an acoustic logging tool into a wellbore, performing a measurement operation with the acoustic logging too in the wellbore to form a data set which comprises one or more guided waves, measuring a speed of the one or more guided waves, and identifying a fluid phase interface using the speed of the one or more guided waves. The method may further comprise estimating an acoustic velocity of a wellbore fluid using a database and interpreting the fluid phase based at least in part on the acoustic velocity of the wellbore fluid.