Acoustic Source Localization in Borehole Leak Detection
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Solution Overview
Problem
Current methods for detecting fluid leaks around a borehole, such as those in oil and gas operations, are inadequate in accurately locating acoustic sources outside and around the borehole, particularly behind the casing, which can lead to inefficiencies and safety hazards due to undetected leaks.
Innovation Solution
A method and system utilizing acoustic sensors spaced along a tool within the borehole to receive and process acoustic data signals, calculating stacked energies for different radial distances by offsetting signals based on a borehole model, and evaluating these energies to determine the radial distance of acoustic sources, including fluid leaks, by comparing them to a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic sensors are used to detect fluid leaks around a borehole, then leak detection capability is improved, but the ability to accurately locate the acoustic source radially from the borehole deteriorates
Solution Approach 1:
The acoustic detection problem is segmented into multiple radial distance bins. The processor divides the radial space around the borehole into discrete segments and calculates stacked energy for each segment independently. This segmentation allows the system to determine which radial segment contains the acoustic source, thereby achieving radial location accuracy while maintaining reliable leak detection across the entire borehole perimeter.
Solution Approach 2:
The invention adds a radial distance dimension to the acoustic detection problem. By calculating stacked energy at multiple radial distances and comparing these energies, the system transforms a two-dimensional (azimuthal and temporal) acoustic detection problem into a three-dimensional solution that includes radial positioning. This dimensional extension enables accurate radial location determination without compromising leak detection reliability.
2Reliability
If multiple acoustic sensors are spaced along the tool to improve detection coverage, then leak detection reliability is improved, but device complexity increases
Solution Approach 1:
The acoustic sensor array is designed to perform multiple functions simultaneously: detecting leaks, locating acoustic sources radially, and determining azimuthal positions. The same set of spaced sensors used for basic leak detection is also utilized for calculating stacked energy at different radial distances and for azimuthal localization. This multi-functionality improves detection reliability without proportionally increasing device complexity, as the sensors serve several purposes rather than requiring separate dedicated systems.
Solution Approach 2:
The invention merges the functions of leak detection, radial localization, and azimuthal positioning into a single integrated acoustic sensor array system. The processors combine the acoustic signals from all sensors to simultaneously achieve multiple objectives: identifying the presence of leaks, determining their radial distance from the borehole, and locating their azimuthal position. This merging reduces overall system complexity compared to having separate systems for each function.
3Measurement precision
If stacked energy calculation with time offsetting is used to improve radial distance determination, then measurement precision is improved, but processing complexity increases
Solution Approach 1:
The system performs preliminary time offsetting of acoustic signals based on expected acoustic travel times to different radial distances before summing the signals. By pre-calculating the time offsets corresponding to various radial distances and applying these offsets before stacking, the system simplifies the subsequent energy calculation process. This preliminary action enables accurate radial distance determination without requiring complex iterative processing, as the time alignment is established in advance based on the borehole model.
Solution Approach 2:
The invention changes the time parameter of acoustic signals by applying time offsets corresponding to different radial distances. By transforming the temporal domain parameters of the acoustic signals according to the borehole model, the system enables radial distance determination through energy comparison. This parameter transformation approach simplifies the processing complexity compared to analyzing raw acoustic signals directly, as it converts the radial location problem into a time-domain energy comparison problem.
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
This approach enables precise identification and localization of acoustic sources, enhancing the integrity of the borehole and well operations by detecting leaks and reducing hazardous conditions, thereby improving efficiency and safety.
Implementation Method 1
receiving acoustic data signals from respective acoustic sensors spaced along a tool lowered within the borehole
Implementation Method 2
a borehole model specifying acoustic delay to the respective acoustic sensor as a function of the radial distance from the borehole
Data Source
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Figure 2
Figure 3~4
AI summary
Systems, methods, and computer-readable storage devices for determining a location of an acoustic source outside of a borehole. The method relates to indicating a radial distance to the borehole, an offset along the borehole, and an azimuthal position around the borehole, of the acoustic source. The method includes receiving acoustic signals from respective acoustic sensors spaced along a tool lowered within the borehole. Using the acoustic signals and a borehole model, stacked energies are calculated for different radial distances from the borehole. At least one of the stacked energies is translated to an indication of a radial distance of the acoustic source from the borehole. The stacked energy for a radial distance is computed by offsetting the acoustic data signals in time in accordance the borehole model, summing the offset acoustic data signals to produce a stacked signal, and evaluating energy of the stacked signal over a time window.