Multi-well Anisotropy Inversion for Deviated Boreholes
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Solution Overview
Problem
Current methods for characterizing anisotropic earthen formations, particularly in oil and gas exploration, face challenges in accurately determining anisotropy parameters like Thomsen parameters ε, δ, and γ, which are crucial for well completion, seismic migration, and hydraulic fracturing, due to the complexity of seismic data interpretation and the need for extensive resource allocation.
Innovation Solution
A method and system that provide compressional and shear-wave slowness data for deviated borehole angles, establish relationships between normal and tangential compliances, and calculate anisotropy parameter values using optimized elastic coefficients, enabling the estimation of Thomsen parameters for horizontal sections of wells, thereby characterizing homogeneous anisotropic formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods are used to characterize anisotropic formations, then well completion and seismic migration can be performed, but the accuracy of anisotropy parameter estimation is insufficient and resource allocation is excessive
Solution Approach 1:
The patent transforms the complex seismic data interpretation problem into a parameter optimization problem by defining an objective function that quantifies the mismatch between measured and synthetic slowness data. The method systematically varies elastic coefficients (C11, C33, C44, C66, C13) and Thomsen parameters (ε, δ, γ) to minimize this objective function, converting a qualitatively complex interpretation task into a quantitatively tractable parameter estimation problem.
Solution Approach 2:
The patent replaces traditional mechanical/seismic wave propagation analysis with a computational optimization approach. Instead of directly analyzing complex seismic wave behavior through the anisotropic formation, the method uses numerical optimization algorithms to adjust model parameters until synthetic data matches measured data, substituting physical analysis with computational mathematics.
2Reliability
If extensive resources are allocated to seismic data interpretation, then formation characterization can be performed, but the process becomes inefficient and time-consuming
Solution Approach 1:
The patent performs preliminary actions by pre-defining the objective function and the parameter space before actual data analysis. The method prepares the computational framework in advance, including the synthesis of seismic data using proposed elastic coefficients, so that when actual measurement data is available, the optimization process can immediately begin without ad-hoc setup, significantly improving processing efficiency.
Solution Approach 2:
The optimization process is self-correcting and self-guiding. The objective function automatically quantifies the error between measured and synthetic data, and the optimization algorithm autonomously adjusts parameters to minimize this error without requiring external intervention or manual interpretation, making the process both reliable and efficient.
3Productivity
If simple models are used for anisotropy parameter calculation, then computational speed increases, but the accuracy of Thomsen parameter estimation decreases
Solution Approach 1:
The patent segments the complex anisotropy characterization problem into distinct, independently optimizable components: compressional wave slowness data optimization, shear wave slowness data optimization, and Tangential Compliance optimization. Each segment focuses on specific elastic coefficients and parameters, allowing the complex problem to be solved through multiple simpler, focused optimization passes rather than one monolithic complex optimization.
Solution Approach 2:
The patent adds the dimension of iterative optimization to the parameter estimation process. Instead of using a single-pass simple calculation, the method introduces an iterative loop where parameters are continuously refined based on the objective function feedback, transforming a static simple calculation into a dynamic multi-dimensional optimization process that achieves both speed and accuracy.
Data Source
AI summary
A method can include providing compressional and shear-wave slowness data for a homogeneous, anisotropic formation at deviated borehole angles greater than 40 degrees and less than 90 degrees as defined by a vertical transverse isotropy (VTI) symmetry axis; providing a relationship for normal and tangential compliances (e.g., BN and BT); and, based on the data and the relationship, outputting a model for calculating anisotropy parameter values (e.g., α0, ε, .δ) that characterize the homogeneous, anisotropic formation (e.g., along a borehole angle of 90 degrees). Various other apparatuses, systems, methods, etc., are also disclosed.