Nonlinear Direct Prestack Seismic Inversion for Poisson Impedance
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Solution Overview
Problem
Current methods for lithology identification and fluid discrimination in seismic exploration and reservoir characterization face challenges due to uncertainties and accumulative errors from indirect calculations, particularly in estimating fluid factors using prestack seismic inversion, which affects the accuracy of hydrocarbon predictions and reservoir characterization.
Innovation Solution
A computer-implemented method and system that employs a nonlinear direct prestack seismic inversion model, utilizing Poisson impedance and incorporating a well-to-seismic tie approach, to directly estimate elastic properties by combining angle image gathers, low-frequency models, and angle wavelets, thereby reducing uncertainties and biases from indirect calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect calculation methods are used to estimate fluid factors from prestack seismic inversion, then the computational complexity is reduced, but the measurement precision and reliability of Poisson impedance estimation deteriorate due to uncertainties and accumulative errors
Solution Approach 1:
The patent inverts the conventional approach by directly estimating Poisson impedance from prestack seismic data without relying on indirect calculations through elastic parameters. This inversion of the estimation sequence eliminates accumulative errors and provides more accurate fluid factor predictions while maintaining computational feasibility through a streamlined direct estimation algorithm
Solution Approach 2:
The patent extracts and eliminates the intermediate calculation steps involving elastic parameters (bulk modulus, shear modulus) that introduce uncertainties. By directly computing Poisson impedance from seismic amplitude versus offset data, the method removes the source of accumulative errors while preserving the essential computational workflow
2Ease of operation
If conventional prestack seismic inversion models are used, then the ease of operation is maintained, but the manufacturing precision of lithology identification and fluid discrimination deteriorates due to biases from indirect calculations
Solution Approach 1:
The patent changes the fundamental parameter estimation approach from indirect elastic parameter calculation to direct Poisson impedance estimation. This parameter transformation eliminates systematic biases in lithology identification and fluid discrimination while maintaining the operational simplicity of automated seismic inversion workflows through a direct mathematical relationship between seismic data and Poisson impedance
3Device complexity
If indirect estimation methods are used for fluid factors, then the device complexity is reduced, but the reliability of hydrocarbon predictions deteriorates due to accumulative errors
Solution Approach 1:
The patent inverts the estimation hierarchy by making Poisson impedance the primary estimated parameter rather than a derived parameter from elastic moduli. This inversion directly addresses hydrocarbon prediction reliability by eliminating the chain of indirect calculations that introduce accumulative errors, while the system complexity remains manageable through efficient direct estimation algorithms
Data Source
AI summary
A computer-implemented method, and system implementing the method, are disclosed for computing a final model of elastic properties, using nonlinear direct prestack seismic inversion for Poisson impedance. User inputs and earth-model data is obtained over points of incidence of a survey region, at various angles of incidence. Various models are then computed that serve for lithology identification and fluid discrimination and take part in preliminary seismic exploration and reservoir characterization. Therefore, further refinement of these models is required due to changes in burial depths, compaction and overburden pressure, as they provide limitations for reservoirs on porous media. The further refinement using nonlinear direct prestack seismic model is performed on a system computer, which produces a final model of elastic properties. This model can then be applied for lithology prediction and fluid detection to identify potential targets of oil and gas exploration and estimating spots in unconventional shale gas applications.