Azimuthal Borehole Sonic Interpolation for Fine Resolution
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Solution Overview
Problem
Conventional wireline sonic tools have limited azimuthal receivers, resulting in inadequate azimuthal resolution for accurate imaging and data interpretation in hydrocarbon exploration, particularly for monopole and higher multipole order data, which are critical for decision-making in processing steps like imaging away from the well bore.
Innovation Solution
A logging tool with transmitters and receivers that uses interpolation techniques, specifically 2D Fast Fourier Transforms and inverse transforms, to generate interpolated multicomponent measurements at fixed azimuths, increasing azimuthal coverage and enabling the determination of hydrocarbon-bearing formation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wireline sonic tools use limited azimuthal receivers (4 or 8 receivers), then the device complexity is reduced and manufacturing is easier, but the azimuthal resolution is insufficient (90 or 45 degrees) for accurate imaging processing requiring 10 degrees resolution
Solution Approach 1:
The patent replaces the mechanical approach of using numerous physical receivers with a signal processing approach. By applying interpolation techniques to the data from fewer receivers, the system achieves fine azimuthal resolution (10 degrees) without requiring a correspondingly large number of physical sensors, thus reducing device complexity while improving measurement precision
Solution Approach 2:
The patent changes the parameter of azimuthal sampling by using interpolation algorithms that generate synthetic receiver responses at intermediate azimuths. This transforms the discrete azimuthal samples from limited receivers into a continuous azimuthal coverage, achieving 10-degree resolution without physically installing receivers at every azimuth position
2Measurement precision
If conventional methods use Alford's rotation method to obtain dipole signals at arbitrary azimuths, then the processing is simplified, but monopole and higher multipole order data are not rotated, leading to loss of critical information and decreased accuracy
Solution Approach 1:
The patent implements a universal rotation framework that applies the same interpolation-based rotation technique to all multipole orders (monopole, dipole, quadrupole, hexapole). This single approach handles all data types consistently, improving measurement precision across all orders while the modular implementation keeps processing complexity manageable
Solution Approach 2:
The patent performs preliminary rotation of all multipole order data before further processing steps. By rotating the monopole and higher multipole data in advance using interpolation techniques, the system ensures that critical information is preserved and properly oriented for subsequent interpretation, preventing loss of accuracy that would occur if these components were skipped
3Device complexity
If tools use 4 receivers with 90 degree azimuthal sampling, then the device complexity is minimized, but the azimuthal coverage is insufficient for fine imaging processing requiring 10 degree resolution
Solution Approach 1:
The patent creates virtual copies of the receiver data through interpolation. By generating synthetic receiver responses at intermediate azimuth positions between the physical receivers, the system effectively copies and extends the information from the 4 physical receivers to cover all 360 degrees at 10-degree intervals, preventing information loss without adding physical receivers
Data Source
AI summary
Multicomponent data are acquired using a downhole acoustic tool having transmitters and receiver stations distributed azimuthally in a plane perpendicular to the axis of the tool. The receiver stations are located at several receiving stations along the axis of the tool. At each acquisition depth, waveforms are processed through a multi-dimensional fast Fourier transform, extrapolation and inverse multi-dimensional fast Fourier transform. At each receiver station, waveforms are combined to produce the standard monopole waveforms and the inline and crossline dipole waveforms along fixed azimuths. These oriented waveforms produce a finer azimuthal sampling of the surrounding formation, and can then be used for imaging geological features within the surrounding formation.