Stress and Fracture Modeling Using Superposition
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Solution Overview
Problem
Conventional stress inversion methods fail to accurately account for complex fault geometries and heterogeneous rock conditions, leading to inefficient computation and incomplete mechanical treatment of tectonic deformation, as they assume uniform stress fields and ignore perturbations caused by fault interactions.
Innovation Solution
The implementation of a stress and fracture modeling system using the principle of superposition, which simulates linearly independent far field stress models to compute stress, strain, and displacement values, incorporating diverse geologic data such as fault geometry, well bore data, GPS, and InSAR data to recover paleostress values and predict fracture propagation in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional stress inversion methods are used, then computation is simpler, but accuracy is reduced due to uniform stress field assumptions and ignored fault interactions
Solution Approach 1:
The stress field is segmented into far-field uniform stress components and near-field perturbed stress components caused by individual faults. Each fault's contribution to stress perturbation is calculated separately and then superimposed to obtain the total perturbed stress field, enabling accurate modeling of fault interactions without requiring full recomputation for each fault combination.
Solution Approach 2:
The patent pre-calculates the stress perturbation tensors for each fault based on their geometry and mechanical properties before performing the inversion. These pre-computed perturbation tensors are then used during the inversion process to rapidly evaluate different stress models, significantly reducing computation time while maintaining accuracy.
2Measurement precision
If multiple simulations are run to account for fault interactions, then accuracy improves, but computation time increases enormously
Solution Approach 1:
The patent changes the approach from running multiple full simulations to using analytical solutions that compute stress perturbations as functions of fault geometry parameters. By expressing perturbed stress in terms of fault length, depth, dip, and slip parameters, the system can rapidly evaluate different fault configurations without time-consuming numerical simulations.
Solution Approach 2:
Instead of running new simulations for each fault configuration, the patent creates analytical copies of the stress field solutions that can be rapidly evaluated by simply changing input parameters. The pre-computed perturbation tensors serve as templates that can be quickly adapted to different fault geometries through parameter substitution rather than full recomputation.
3Productivity
If conventional methods ignore fault slip perturbations, then computation is faster, but mechanical treatment of tectonic deformation is incomplete
Solution Approach 1:
The patent introduces perturbed stress tensors as intermediary quantities that mediate between the far-field uniform stress and the actual local stress field. These perturbation tensors capture the mechanical effect of fault slip and interactions, allowing the system to efficiently compute the complete mechanical treatment by adding the intermediary perturbation field to the far-field stress.
Data Source
AI summary
Stress and fracture modeling using the principal of superposition is provided. A system simulates linearly independent far field stress models for a subsurface earth volume, computing stress, strain, and displacement values based on superposition of independent stress tensors. Based on the precomputed values, the system generates real-time recovery of paleostress values, or, stress, strain, and displacement parameters for any point in the subsurface volume as the user varies far field stress values. The system recovers one or more tectonic events, or a stress tensor represented by a ratio of principal magnitudes and associated orientation, using fault geometry, well bore data (fracture orientation and secondary fault plane data), GPS, InSAR, folded and faulted horizons, tiltmeters, slip and slikenlines on faults. The system uses different geologic data from seismic interpretation, well bore readings, and field observation to provide numerous results, such as predicted fracture propagation based on perturbed stress field.