Reflection-Only Acoustic Sensor for Downhole Fluid Impedance
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Solution Overview
Problem
Conventional methods for determining downhole fluid parameters, such as acoustic impedance and sound speed, are sensitive to drilling fluid properties and require complex calibration, making them unsuitable for Measurement-While-Drilling (MWD) and Logging-While-Tripping (LWT) tools due to size constraints and signal attenuation issues in particle-laden fluids.
Innovation Solution
A reflection-only acoustic assembly with two solid acoustic transmission media of different impedances and sound speeds, allowing for self-calibration and estimation of fluid parameters without transmitting acoustic pulses through the fluid, using the ratio of reflection intensities to determine fluid impedance and sound speed, thus avoiding time-of-flight measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time-of-flight methods are used to determine sound speed and acoustic impedance, then measurements can be obtained, but the methods are highly sensitive to drilling fluid properties and require complex calibration
Solution Approach 1:
The acoustic assembly performs self-calibration by utilizing the known acoustic properties of its own solid transmission media. The system determines fluid parameters by comparing reflections from the solid-fluid interfaces against the known characteristics of the solid media, eliminating the need for external calibration procedures and making the measurements independent of drilling fluid property variations
Solution Approach 2:
Solid acoustic transmission media with known acoustic properties serve as intermediaries between the transducer and the drilling fluid. These media facilitate measurements by providing stable, known reference acoustic impedances and sound speeds, allowing the system to determine fluid parameters through reflection comparisons without being directly exposed to or affected by fluid property variations
2Measurement precision
If acoustic pulses are transmitted through the drilling fluid, then fluid parameters can be measured, but signal attenuation occurs in particle-laden fluids
Solution Approach 1:
The measurement method extracts the acoustic reflection signals at the solid-fluid interfaces before the acoustic energy propagates through the particle-laden drilling fluid. By measuring reflections at the near-end interfaces and using known far-end interface characteristics, the system obtains fluid parameter information without transmitting acoustic pulses through the attenuating fluid medium
3Measurement precision
If larger acoustic assemblies are used for time-of-flight measurements, then measurement accuracy improves, but the tools become too large for MWD and LWT applications
Solution Approach 1:
The acoustic assembly is segmented into multiple solid transmission media with different acoustic properties (different acoustic impedances and/or sound speeds). This segmentation allows the system to determine fluid parameters by comparing reflections from multiple interfaces, achieving accurate measurements with a compact configuration suitable for MWD and LWT tools rather than requiring a single large measurement path
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
Enables accurate estimation of downhole fluid parameters like sound speed, acoustic impedance, and density without the need for time-of-flight analysis, allowing for smaller, more efficient measurement tools that can operate in particle-laden drilling fluids with higher frequency transducers and reduced risk of clogging.
Implementation Method 1
providing an acoustic pulse with an acoustic transducer that propagates within the two media
Implementation Method 2
receiving the reflection of the pulse having reflected amplitudes, respectively, from the solid-liquid interface at the corresponding face of the first medium and the second medium
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Methods, systems, and devices for estimating a parameter of interest of a downhole fluid. Methods may include using at least two solid acoustic transmission media, including a first media and a second media having different acoustic impedances and each having a corresponding face immersed in the downhole fluid. Methods may include using a reflection of an acoustic pulse from a solid-liquid interface at the corresponding face of the first media and the second media to estimate the parameter of interest. The sound speed and the acoustic impedance of the first media and the sound speed and the acoustic impedance of the second media may each be different than a sound speed and an acoustic impedance of the fluid and each other. The parameter of interest may be estimated independently of a time of flight in the downhole fluid of any acoustic pulses.