Elastic Parameter Estimation in Anisotropic Formations
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Solution Overview
Problem
Current reflection seismology methods face challenges in accurately characterizing anisotropic subsurface formations, particularly in shale formations, due to limitations in measuring elastic properties and accounting for measurement uncertainties, which affects the interpretation of seismic data for subsurface exploration and reservoir management.
Innovation Solution
A method and system that process sonic data from multiple depths in a borehole to generate processed information including variance and orientation information, performing inversions to output elastic parameters as a continuous description with respect to depth, using a five-parameter model and Thomsen's δ parameter, and accounting for measurement uncertainties to characterize anisotropic formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional reflection seismology methods are used to characterize anisotropic formations, then the interpretation process is simplified, but the accuracy of elastic property measurement deteriorates
Solution Approach 1:
The measurement system is segmented into multiple independent sonic tools deployed at different depths in the borehole, each measuring elastic properties in specific directional orientations. This segmentation allows for comprehensive coverage of anisotropic properties while maintaining manageable complexity in each individual measurement device.
Solution Approach 2:
The patent transitions from traditional single-depth seismic measurement to multi-depth borehole sonic measurement, adding the depth dimension to the measurement system. This dimensional expansion enables accurate characterization of vertical anisotropy in elastic properties that cannot be captured by surface seismic methods alone.
2Measurement precision
If sonic data from multiple depths are processed to generate continuous elastic parameter descriptions, then the characterization accuracy of anisotropic formations is improved, but the data processing complexity increases
Solution Approach 1:
The patent processes sonic data from multiple discrete depth measurements to generate continuous elastic parameter descriptions as a function of depth. This continuous characterization provides uninterrupted information about anisotropic properties throughout the formation interval, improving accuracy while the systematic processing approach manages computational complexity.
Solution Approach 2:
The inversion process transforms the measured sonic data into elastic parameters (such as Thomsen parameters) that directly characterize anisotropy. By changing the parameter space from raw sonic measurements to meaningful elastic properties, the system achieves accurate anisotropic characterization while simplifying the interpretation of complex multi-depth data.
3Reliability
If measurement uncertainties are accounted for in the inversion process, then the reliability of elastic parameter estimation is improved, but the computational requirements increase
Solution Approach 1:
The inversion process incorporates measurement uncertainties as feedback into the estimation algorithm, allowing the system to weight measurements appropriately and propagate uncertainty through the inversion. This feedback mechanism improves the reliability of elastic parameter estimates by accounting for data quality variations while the iterative nature of the inversion manages computational demands.
Solution Approach 2:
The patent applies uncertainty accounting selectively to the most critical measurements and parameters in the inversion process, rather than uniformly to all data. This partial application of uncertainty analysis improves reliability for key elastic parameters while avoiding the excessive computational burden of comprehensive uncertainty propagation throughout the entire dataset.
Data Source
AI summary
A method includes receiving information that includes elastic property information and that includes sonic data acquired via a tool disposed at a plurality of depths in a bore in a subterranean environment that includes at least one anisotropic formation; processing the information to generate processed information where the processed information includes variance information associated with the elastic property information and where the processed information includes velocity information and orientation information associated with the sonic data; performing an inversion based at least in part on the processed information; and outputting values for elastic parameters based at least in part on the inversion.