Downhole Acoustic Sand Detection via Power Spectral Density Analysis
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Solution Overview
Problem
Existing methods struggle to efficiently detect and quantify sand flows in tubular structures of oil or gas wells, leading to asset degradation and reduced production due to sand erosion of sand screens, which is difficult to monitor and remediate in real-time.
Innovation Solution
An embedded computing device collects acoustic data at predefined discrete frequencies, using Power Spectral Density (PSD) comparisons to determine the presence and concentration of sand in fluid flows, sending real-time notifications to the surface for timely remediation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sand screens are used to restrict sand flow into the well, then sand ingress is reduced, but the sand screen becomes eroded over time due to sand impacts
Solution Approach 1:
The system performs preliminary detection of sand flow conditions using acoustic sensors and PSD analysis before significant erosion occurs. By continuously monitoring acoustic signatures and comparing PSD values against thresholds, the system can identify sand flow conditions early and alert operators to take preventive actions, thereby extending sand screen service life while maintaining integrity.
2Loss of information
If logging data is collected to determine sand impact on the well, then sand flow information is obtained, but it is impractical and difficult to efficiently deliver this information
Solution Approach 1:
The system extracts only the most critical information - the comparison result between measured and threshold PSD values - and transmits this extracted data to the surface. By using an embedded computing device to perform the complex PSD analysis locally and only sending the final determination (sand flow present/absent and concentration levels), the system eliminates the need to transmit large volumes of raw acoustic data, thereby efficiently delivering sand flow information without time loss.
Solution Approach 2:
The embedded computing device acts as an intermediary between the acoustic sensors and the surface system. It receives continuous acoustic data, performs real-time PSD analysis, compares results against stored thresholds, and generates simplified output signals or notifications. This intermediary processing eliminates the need for complex data transmission and enables rapid delivery of sand flow information to operators.
3Measurement precision
If acoustic data is collected at multiple frequencies to characterize sand flow, then detection accuracy is improved, but data processing complexity increases
Solution Approach 1:
The system segments the frequency spectrum into discrete frequency bins and calculates Power Spectral Density for each bin independently. By dividing the continuous frequency range into discrete segments and analyzing PSD at each segment, the system maintains high detection accuracy across different sand concentrations while simplifying the processing through modular, frequency-by-frequency analysis rather than analyzing the entire spectrum simultaneously.
Solution Approach 2:
The system transforms the acoustic signal from the time domain to the frequency domain using PSD analysis, changing the parameter representation from time-series waveforms to frequency-based power spectral values. This parameter transformation simplifies the detection process by converting complex temporal patterns into comparable spectral features, enabling accurate sand concentration measurement while reducing processing complexity through established signal processing methods.
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 system provides highly optimized detection and quantification of sand flows, enabling real-time monitoring and efficient remediation to prevent asset degradation and maintain production efficiency.
Implementation Method 1
an acoustic sensor of the logging tool detects acoustic emissions from the sand flow in the tubular structure
Data Source
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AI summary
Disclosed are systems and methods for receiving, by at least one processor, calibration information comprising a first power spectral density (PSD) value and a first sand concentration value at a particular frequency, collecting, by at least one processor, data in a liquid flow at the particular frequency at a first depth in a downhole environment, determining, by the at least one processor, a second power spectral density (PSD) value for the data in the liquid flow at the particular frequency, comparing, by the at least one processor, the second PSD value with the first PSD value and determining that sand is present in the liquid flow when the second PSD value is greater than the first PSD value by a predefined threshold, and quantifying, by the at least one processor, a second sand concentration value of the sand present in the liquid flow based on the first sand concentration value.