Sonic Logging Elastic Tensor Estimation
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Solution Overview
Problem
Current methods require multiple measurements across multiple depths or boreholes to estimate a full elastic tensor, limiting accurate geomechanics and seismic anisotropy modeling in deviated wellbores.
Innovation Solution
A sonic logging system that uses monopole and cross-dipole slowness measurements at a single location to determine a full elastic tensor, enabling accurate estimation of five elastic constants for geomechanics and seismic anisotropy modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurements are taken at multiple depths or boreholes, then the accuracy of elastic tensor estimation is improved, but the complexity of the measurement process and data processing increases
Solution Approach 1:
The patent extracts and utilizes specific wave mode information (fast shear wave and slow shear wave slownesses) from the complex sonic logging data to directly calculate elastic tensor parameters. By focusing on the essential measurement components rather than processing all available data from multiple depths and boreholes, the method achieves accurate elastic tensor estimation while reducing measurement and processing complexity.
2Reliability
If multiple well angles with specific wellbore parameters are used, then the reliability of geomechanics results is improved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent applies partial action by using only the necessary wellbore parameters (well angle and relative dip angle) required for elastic tensor calculation, rather than requiring complete wellbore characterization. This approach maintains geomechanics result reliability while reducing the difficulty of measurement and data collection.
3Adaptability or versatility
If a full elastic tensor is estimated using conventional methods, then complete geomechanics and seismic modeling capability is achieved, but the time and resources required for data acquisition increase
Solution Approach 1:
The patent achieves multi-functionality by enabling a single sonic logging measurement to provide all five elastic tensor parameters (C11, C33, C44, C66, and C13) simultaneously. This universal approach allows the same measurement to support both geomechanics analysis and seismic anisotropy modeling, eliminating the need for separate measurements at multiple depths or boreholes and significantly reducing data acquisition time.
Data Source
AI summary
A method and system for estimating a full elastic tensor. The method may comprise taking a measurement for compressional wave sonic data and cross-dipole shear data with a sonic logging tool at a first location as cross-dipole data, processing the compressional wave sonic data to produce a compressional wave slowness (P), and processing the cross-dipole shear data to produce a fast horizontal polarized shear wave slowness (SH) and a slow quazi-vertical shear wave slowness (qSV) as a function of depth. The method may further comprise setting an initial guess for at least five constants of the full elastic tensor for Vertical Transversely Isotropy (VTI) symmetry, determining a modeled slowness surfaces from the full elastic tensor, and comparing the modeled slowness surfaces with measured values of the P, the SH, and the qSV. The method may be performed by a system comprising a sonic logging tool and an information handling system.