Passive Acoustic Wellbore Fluid Identification
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Solution Overview
Problem
Current techniques for monitoring cement slurry placement and well integrity in oil and gas wells are limited by the shallow depth of investigation and high power requirements for electromagnetic wave-based methods, which are constrained by the lack of a readily available energy source behind the casing.
Innovation Solution
The use of passive acoustic sensors positioned on the outer surface of the casing to measure and record the acoustic signatures of fluids in the annulus, allowing for the identification of cement progression and well integrity without the need for RFID tags or electronic tags, and enabling reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high frequency electromagnetic waves are used to monitor fluids in the annulus, then measurement capability is provided, but depth of investigation is shallow due to high attenuation in wellbore fluids
Solution Approach 1:
The patent replaces electromagnetic wave-based monitoring with acoustic sensing technology. Acoustic sensors detect sound waves generated by fluid flow and cement placement in the annulus, providing measurement capability at greater depths where electromagnetic waves are heavily attenuated. This substitution of the physical sensing mechanism resolves the contradiction between measurement capability and depth of investigation.
2Length of stationary object
If more power is transmitted to increase depth of investigation for electromagnetic waves, then depth of investigation is improved, but power requirements become unmanageable due to lack of energy source behind casing
Solution Approach 1:
By replacing electromagnetic sensing with acoustic sensing, the system eliminates the need for high-power energy transmission downhole. Acoustic sensors can detect fluid dynamics and cement placement using sound waves generated by the fluids themselves, requiring minimal power compared to electromagnetic systems that would need to transmit significant energy through the wellbore fluids to achieve deep investigation.
Solution Approach 2:
The acoustic sensing system utilizes sound waves naturally generated by fluid flow and cement placement in the annulus. The fluids themselves generate the acoustic signals that are detected by the sensors, eliminating the need for an external energy source to provide the investigation capability. The system serves itself by using the process being monitored to provide the measurement signal.
3Reliability
If active electronic devices are placed behind casing to monitor fluid and cement flow, then monitoring capability is provided, but device design is constrained by lack of readily available energy source
Solution Approach 1:
The patent replaces active electronic devices requiring power with passive acoustic sensing technology. Instead of using powered electronic sensors behind the casing, the system uses acoustic sensors that detect sound waves from fluid flow and cement placement. This eliminates the need for power sources, batteries, or energy-consuming electronics, thereby removing the design constraints imposed by the lack of energy availability while maintaining monitoring capability.
Solution Approach 2:
The acoustic sensing system operates without requiring an external energy source. The sensors detect acoustic signals generated by the fluids and cement themselves, making the system self-powered through the natural acoustic emissions of the materials being monitored. This self-service capability eliminates the design constraints that would otherwise limit device placement and operation behind the casing.
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 allows for effective monitoring of cement placement, curing, and well integrity, enabling timely and cost-effective well operations, including hydraulic fracturing and perforation management, with improved accuracy and reduced energy requirements.
Implementation Method 1
measuring an acoustic noise generated by one or more reference materials and thereby generating a corresponding one or more acoustic profiles, monitoring an annular material in a wellbore with at least one acoustic sensor positioned in the wellbore and thereby obtaining an acoustic response of the annular material
Data Source
AI summary
Determining a type of annular material in a wellbore comprises measuring an acoustic noise of one or more reference materials and thereby generating a corresponding one or more acoustic profiles, monitoring the annular material with an acoustic sensor positioned in the wellbore and thereby obtaining an acoustic response of the annular material, comparing the acoustic response with the one or more acoustic profiles using a processor communicably coupled to the acoustic sensor, and characterizing the annular material based on the comparison of the acoustic response and the one or more acoustic profiles.