Probabilistic Fault Seal Analysis for Shale Smear Breaches
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Solution Overview
Problem
Existing methods for fault seal analysis, such as the Shale Gouge Ration (SGR) technique, face uncertainties in estimating the volume and plasticity of clays, assuming plastic behavior of shales without accounting for breaches, calculating asymmetrical shale volumes, and estimating gouge permeability with uncertain parameters.
Innovation Solution
A probabilistic stochastic method is employed to consider discrete occurrences of shale smears and smear breaches along a fault gouge, integrating smear placement models to determine the likelihood of smear presence, and using probabilistic calculations for VClay, fault throw scenarios, and ductility parameters to perform stochastic simulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional SGR method is used to estimate fault sealing potential, then the calculation is simple and continuous, but it introduces uncertainties in estimating clay volume and plasticity, and assumes plastic behavior without accounting for breaches
Solution Approach 1:
The patent segments the continuous fault gouge into discrete elements (shale smears and smear breaches) along the fault plane. Instead of treating the fault as a continuous medium with averaged properties, the method divides it into discrete segments that can individually be classified as either shale smear (sealing) or breach (non-sealing), thereby capturing the heterogeneous nature of fault zones while maintaining computational tractability through probabilistic segmentation.
Solution Approach 2:
The patent transforms the deterministic parameters of traditional SGR (continuous shale volume ratio) into probabilistic parameters (likelihood of smear presence, ductility factors, breach probabilities). By changing from fixed parameter values to probability distributions, the method accounts for uncertainties in clay volume estimation and plasticity behavior, allowing for a more robust assessment of fault sealing potential that incorporates natural variability and measurement uncertainties.
2Ease of manufacture
If shale volumes are calculated on one side of the fault (footwall), then the calculation is simplified, but it leads to asymmetrical smearing and inaccurate seal assessment
Solution Approach 1:
The patent creates a universal smear placement model that can operate on data from either side of the fault (footwall or hangingwall) or both sides simultaneously. The probabilistic framework is designed to be side-agnostic, accepting input from any configuration and producing consistent results. This universal approach eliminates the need to choose a specific side for calculation while maintaining accuracy in asymmetrical fault scenarios.
Solution Approach 2:
The patent moves from a one-dimensional calculation (shale volume on one side) to a two-dimensional probabilistic model that considers smear placement across the entire fault plane. By introducing the dimension of probability and spatial distribution along the fault strike and dip, the method captures asymmetrical smearing patterns that arise from differential movement between fault blocks, providing a more comprehensive view of seal potential.
3Ease of operation
If gouge permeability is estimated using traditional parameters (breakthrough pressure, fault gouge thickness, cataclasis), then the estimation can be performed with available data, but it relies on uncertain parameters and may not accurately reflect actual flow behavior
Solution Approach 1:
The patent replaces the mechanical/permeability-based approach (using breakthrough pressure and cataclasis to estimate flow properties) with a discrete element approach based on smear presence and breach occurrence. Instead of calculating effective permeability through complex mechanical models, the method uses binary states (smear present/absent, breach present/absent) combined with probabilistic reasoning to determine flow potential, thereby substituting a simplified discrete model for a continuous mechanical system.
Solution Approach 2:
The patent transforms uncertain continuous parameters (breakthrough pressure, cataclasis degree) into discrete probabilistic parameters (likelihood of smear presence, probability of breach). By changing from continuous parameters with high uncertainty to discrete states with probabilistic characterization, the method reduces sensitivity to parameter estimation errors while maintaining the ability to assess permeability and flow behavior through the statistical distribution of smear and breach elements.
Data Source
AI summary
Some implementations include a method for detecting leaks across a geological fault. The method may include determining probabilities of smears and smear breaches along a fault plane of the geological fault; and determining, based on the probabilities, one or more leak points through which hydrocarbon fluid leaks from a subsurface reservoir.