Acoustic Logging Tool Dispersion Modeling
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Solution Overview
Problem
The presence of acoustic logging tools in boreholes alters the acoustic propagation environment, leading to inaccurate measurements of geologic formation properties, particularly for flexural waves, due to unaccounted dispersion effects.
Innovation Solution
A simplified acoustic logging tool model using concentric cylindrical shells with homogeneous properties is simulated to determine acoustic dispersion, which is then used to improve the accuracy of geologic formation inversion and reduce the tool's influence on measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic logging tools are deployed in boreholes to measure formation properties, then measurement capability is provided, but the tool's presence alters the acoustic propagation environment causing measurement inaccuracy
Solution Approach 1:
The patent creates a computational model that replicates the acoustic logging tool's structure and material properties. This virtual copy is used to simulate and predict the tool's dispersion effects on acoustic wave propagation, allowing the harmful effects to be characterized and compensated for in the actual measurements without modifying the physical tool itself.
Solution Approach 2:
The patent introduces a computational modeling framework as an intermediary between the physical tool and the measurement process. This intermediary model acts as a bridge that translates the tool's physical characteristics into predicted dispersion effects, enabling correction of the measurements without direct modification of the tool-formation interaction.
2Measurement precision
If the acoustic logging tool structure is modeled in detail to account for dispersion effects, then measurement accuracy improves, but computational complexity increases
Solution Approach 1:
The patent transforms the complex structural modeling problem into a parameter-based approach. Instead of modeling the entire tool geometry in detail, the system uses measured or specified material parameters (density, elastic moduli, damping coefficients) to directly compute dispersion effects. This parameterization simplifies the computational model while maintaining accuracy for the specific application.
Solution Approach 2:
The patent applies different levels of modeling detail to different parts of the system. The computational model focuses specifically on the acoustic properties and dispersion characteristics of the tool components, using simplified representations where full geometric detail is not necessary, while maintaining detailed material property descriptions where they most impact the acoustic behavior.
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 enhances the accuracy of geologic formation property determination by accounting for the tool's dispersion contribution, allowing for more precise analysis of acoustic waves and improved measurement results.
Implementation Method 1
An acoustically transmitting transducer is located in the borehole and is electrically driven to insonify a region nearby the transducer. Insonification induces propagating acoustic waves in the borehole, within the geologic formation through which the borehole extends
Implementation Method 2
Acoustic waves propagating within or along the acoustic logging tool body encounter an acoustic frequency-dependent or dispersive effect
Data Source
AI summary
Apparatus and techniques described herein include receiving information indicative of a first cylindrical shell representing a portion of an acoustic logging tool, receiving information indicative of a second cylindrical shell concentrically surrounding the first cylindrical shell, the second cylindrical shell representing a second portion of the acoustic logging tool, and the second cylindrical shell comprising a fluid metal model including a non-zero density, a non-zero compressional wave propagation velocity, and a shear wave propagation velocity of zero or about zero. Information is determined indicative of an acoustic dispersion comprising a slowness (or other information indicative of a propagation velocity) of a wave propagating along the acoustic logging tool using a model including the first and second cylindrical shells.