Reflection-Only Acoustic Sensor for Downhole Fluid Analysis
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Solution Overview
Problem
Current methods for determining downhole fluid parameters, such as sound speed and acoustic impedance, are sensitive to experimental errors and require complex calculations, making them unsuitable for real-time measurement in space-restrictive downhole applications like Measurement-While-Drilling (MWD) and Logging-While-Tripping (LWT) tools.
Innovation Solution
A reflection-only instrument using a single solid acoustic transmission medium with multiple transducers to generate acoustic pulse reflections at various angles, allowing estimation of fluid parameters like sound speed and acoustic impedance without measuring time-of-flight, thereby reducing sensitivity to experimental errors and enabling near-real-time data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time of flight measurement is used to determine sound speed, then measurement capability is achieved, but sensitivity to experimental errors increases and real-time processing becomes difficult
Solution Approach 1:
The invention extracts the time-of-flight measurement component from the measurement system and replaces it with reflection amplitude analysis. By removing the problematic time measurement mechanism and using only reflection amplitude data at different angles, the system achieves sound speed determination without the experimental error sensitivity associated with time-of-flight measurements.
Solution Approach 2:
The invention substitutes the mechanical time measurement system with an acoustic reflection amplitude analysis system. Instead of measuring the time it takes for acoustic waves to travel through the fluid, the system uses the amplitudes of reflected waves at different angles to calculate sound speed, replacing a mechanical measurement approach with an acoustic field analysis approach.
2Measurement precision
If complex calculations are used to determine fluid parameters, then measurement accuracy is improved, but processing speed decreases making real-time measurement impossible
Solution Approach 1:
The invention extracts and eliminates the complex calculation components from the measurement system. By using a simplified relationship between reflection amplitudes at different angles and fluid parameters, the system achieves accurate fluid parameter determination without requiring complex mathematical computations, thereby enabling real-time processing.
Solution Approach 2:
The invention changes the measurement parameters from time-of-flight and complex multi-parameter calculations to reflection amplitude ratios at different angles. This parameter transformation simplifies the computational requirements while maintaining measurement accuracy, allowing for rapid real-time processing of fluid parameters.
3Measurement precision
If acoustic transmission medium contacts downhole fluid, then measurement capability is achieved, but fluid chamber pack-off occurs
Solution Approach 1:
The invention extracts the acoustic transmission medium from direct contact with the downhole fluid. By using a reflection-only configuration where the acoustic medium does not form a fluid chamber, the system eliminates the pack-off problem while maintaining acoustic measurement capability through analysis of reflections at the interface.
Solution Approach 2:
The invention inverts the conventional approach by using reflection measurements instead of transmission measurements through the fluid. Instead of sending acoustic waves through the fluid chamber and measuring what emerges, the system measures only the reflected waves at the interface, eliminating the need for a fluid-filled chamber and preventing pack-off.
4Length of stationary object
If lower frequency acoustic signals are used, then penetration depth is improved, but measurement resolution decreases
Solution Approach 1:
The invention changes the measurement approach from time-of-flight measurement to reflection amplitude analysis. This parameter change allows the use of higher frequency acoustic signals because the measurement does not depend on precise time measurement through the fluid, thereby improving measurement resolution while maintaining adequate penetration depth through the reflection-based measurement mechanism.
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 provides accurate and continuous estimation of downhole fluid parameters, such as sound speed and acoustic impedance, with reduced experimental error and increased robustness for use in MWD and LWT tools, avoiding issues like fluid chamber pack-off and allowing higher frequency acoustic usage.
Implementation Method 1
using characteristics of a plurality of acoustic pulse reflections from a solid-liquid interface at a face of the solid acoustic transmission medium
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~4
AI summary
Methods, systems, and devices for determining a parameter of interest of downhole fluid using an acoustic assembly comprising a single solid acoustic transmission medium having a face immersed in the downhole fluid. Methods include using characteristics of a plurality of acoustic pulse reflections from a solid-liquid interface at the face of the solid acoustic transmission medium to estimate the parameter of interest in near real-time. The characteristics may comprise a corresponding reflection amplitude and the corresponding unique angle of reflection for each acoustic pulse reflection. Methods may include generating a two dimensional data set from measured characteristics, generating a curve by performing data fitting on the two dimensional data set, and using the reciprocal slope of the curve to estimate the parameter of interest. Methods may include estimating time-dependent values for the parameter of interest substantially continuously while the acoustic assembly is on a single logging run in the borehole.