Radial Wave Resonance for Borehole Permeability
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Solution Overview
Problem
Current acoustic wellbore logging instruments are unable to directly measure formation permeability effectively, as they lack sensitivity to the permeability-dependent resonances of radial waves in porous formations.
Innovation Solution
A method and apparatus that produce resonances in a borehole fluid and use processor-estimated velocities of fluid and formation motion at resonance frequencies to calculate permeability, leveraging the difference in velocities between the fluid and porous matrix as a function of frequency and permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acoustic wellbore logging instruments are used, then acoustic wave velocities can be measured, but formation permeability cannot be directly measured
Solution Approach 1:
The patent applies mechanical vibration by generating radial acoustic waves at resonant frequencies to excite vibrations in the borehole fluid and formation. The resonance method uses specific frequency vibrations to amplify the interaction between the acoustic waves and the porous formation, enabling permeability measurement through velocity differences at resonant conditions
Solution Approach 2:
The patent changes the measurement parameter from standard acoustic wave velocity to the difference in velocities between borehole fluid and formation matrix at resonant frequencies. This parameter change exploits the permeability-dependent nature of resonance frequencies and velocity differences, transforming an indirect measurement into a direct permeability measurement
2Measurement precision
If resonance frequencies are used to measure permeability, then measurement sensitivity to permeability improves, but measurement complexity increases
Solution Approach 1:
The patent employs periodic action by sweeping through a range of frequencies to identify resonant frequencies where the system exhibits maximum response. The periodic excitation allows the system to naturally resonate at specific frequencies that are sensitive to permeability, enabling precise measurements through frequency-domain analysis
Solution Approach 2:
The patent replaces complex direct permeability measurement mechanics with an acoustic resonance-based measurement system. Instead of directly measuring fluid flow through the formation (which would require complex well testing equipment), the system uses acoustic wave velocity differences at resonance to infer permeability, simplifying the measurement apparatus while maintaining sensitivity
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 formation permeability by identifying resonance frequencies sensitive to permeability, facilitating improved reservoir development operations.
Implementation Method 1
a resonance of radial acoustic waves generated by an acoustic source located in the borehole
Implementation Method 2
an elastic wave generated in radial direction has resonances that are sensitive to the formation permeability
Implementation Method 3
a first measurement indicative of a velocity of fluid motion in the borehole and a second measurement indicative of the velocity of the formation motion at the resonance
Data Source
AI summary
Radial waves are generated in a borehole in a saturated porous earth formation. Measurements are made of the velocity of motion of the formation and the fluid in the formation. The difference in the velocities is indicative of formation permeability.