Acoustic Wellbore Measurement via Bubble Resonance
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Solution Overview
Problem
Accurate measurement of fluid flow conditions in wellbores is hindered by the variability of pressure and temperature conditions, leading to misinterpretation of fluid flow rates due to inaccurate phase composition information, especially in deep and remote locations such as offshore drilling sites.
Innovation Solution
A system and method using acoustic interrogation with a fiber-optic distributed acoustic sensor to measure the behavior of an acoustic probe signal within the wellbore, determining the phase composition by calculating vapor and liquid fractions based on measured attributes, including bubble size parameters, to accurately assess fluid flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluid flow measurement is performed in wellbores with varying pressure and temperature conditions, then flow rate information can be obtained, but measurement accuracy deteriorates due to inaccurate phase composition information
Solution Approach 1:
The patent replaces traditional mechanical phase detection methods with acoustic interrogation. Acoustic sensors measure the speed of sound and attenuation characteristics of the fluid, which vary depending on phase composition. This acoustic field-based approach provides accurate phase information without the complexity and inaccuracy of mechanical sensors in high-pressure, high-temperature wellbore environments
Solution Approach 2:
The patent utilizes changes in acoustic parameters (speed of sound and attenuation) as indicators of phase composition changes. By monitoring these acoustic parameter variations along the wellbore, the system accurately determines fluid phase state and composition, which directly improves fluid flow measurement accuracy
2Productivity
If downhole pressure is maintained at high levels to extract liquid phase natural gas, then production efficiency is improved, but phase composition control becomes difficult leading to freezing and clathrate formation
Solution Approach 1:
The patent implements a feedback control system where acoustic sensors continuously monitor phase composition along the wellbore. This real-time information is fed back to control systems that can adjust production parameters to maintain optimal pressure and temperature conditions, preventing unwanted phase changes and clathrate formation while sustaining high production rates
Solution Approach 2:
The patent uses acoustic interrogation to detect phase composition changes before they lead to problematic conditions such as freezing or clathrate formation. By identifying early signs of phase instability, the system can take preliminary corrective actions to maintain reliable operation
3Measurement precision
If acoustic interrogation is used to measure fluid flow conditions, then phase composition accuracy is improved, but device complexity increases due to need for multiple sensors and data processing
Solution Approach 1:
The patent makes the acoustic sensor system multi-functional. The same acoustic sensors and signal processing system are used to determine both phase composition and fluid flow rate, eliminating the need for separate measurement systems and reducing overall device complexity while maintaining high measurement precision
Solution Approach 2:
The patent combines phase detection and flow measurement functions into a single acoustic interrogation system. By merging these functions and using unified signal processing algorithms, the system achieves accurate phase composition determination without proportionally increasing complexity
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 reliable and accurate determination of fluid flow characteristics by measuring the speed and attenuation of acoustic probe signals, allowing for precise estimation of vapor fractions and bubble sizes, thereby improving the interpretation of fluid flow parameters in wellbores.
Implementation Method 1
measuring behavior of an acoustic probe signal in the fluid medium within the wellbore
Implementation Method 2
measuring the speed and attenuation of acoustic probe signals
Implementation Method 3
acoustic probe signal having a target frequency range that at least partially overlaps a particular bubble resonance frequency range comprising resonant frequencies for a range of individual bubble sizes characteristic of vapor bubble formation
Data Source
AI summary
A method of measuring fluid flow conditions in a wellbore includes generating an acoustic probe signal during fluid flow along the wellbore, measuring the performance attribute of the acoustic probe signal within a target frequency range, and of the fluid medium in at least a part of the wellbore based on the measured performance parameters. The target frequency range of the acoustic probe signal encompasses a bubble resonance frequency range for vapor bubbles in the wellbore, for example having frequencies in excess of 20 kHz. An estimated bubble size value may be calculated based on determining a frequency at which the measured probe signal experiences the retardation or peak attenuation.