Fault Property Modeling for Accurate Subterranean Flow Simulation
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Solution Overview
Problem
Existing subterranean formation models inaccurately represent fault effects due to implicit fault representations, leading to inaccuracies in fluid flow simulations.
Innovation Solution
A method involving geological data transformation to depositional space, followed by gridding and inverse transformation back to structural space, allows for precise determination of fault properties like thickness and permeability, enabling accurate fault transmissibility calculations without relying on fault transmissibility multipliers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If implicit fault representation with fault transmissibility multiplier is used, then reservoir simulation is convenient and simple, but model accuracy deteriorates due to inability to precisely represent fault properties
Solution Approach 1:
The patent segments the fault representation by creating separate fault grid cells that are distinct from regular reservoir cells. Each fault cell is independently defined with its own geometric properties (thickness, orientation, position) and can be assigned specific fault properties (permeability, transmissibility). This segmentation allows the simulation model to explicitly represent fault characteristics rather than implicitly approximating them through multipliers applied to adjacent cells.
2Ease of manufacture
If fault transmissibility multiplier is used to control flow through faults, then the model is simple to implement, but accuracy deteriorates due to oversimplification of fault characteristics
Solution Approach 1:
The patent changes the fundamental parameters used to represent faults from a single transmissibility multiplier to multiple independent parameters including fault thickness, fault orientation, fault position, and fault permeability. These parameters are directly input from geological models and structural interpretations, allowing the simulation to calculate transmissibility based on physical fault characteristics rather than using an empirical multiplier. This parameter transformation enables more accurate representation of fault flow properties.
3Device complexity
If implicit fault representation is used, then grid cell structure remains simple, but accuracy deteriorates due to inability to separately represent fault thickness and permeability
Solution Approach 1:
The patent introduces fault grid cells as intermediary elements between adjacent reservoir cells. These fault cells act as mediators that control fluid flow between reservoir cells on either side of the fault. The fault cells have defined geometric properties that represent the physical fault characteristics, and they serve as the actual flow pathway in the simulation. This intermediary structure allows the model to explicitly represent fault thickness and permeability while maintaining a systematic grid-based computational framework.
Data Source
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AI summary
Methods for modeling and simulating fractured subterranean volumes include a method including obtaining geological data representing a subterranean volume, generating a structural model thereof in depositional space and in structural space. The method includes selecting a first cell and a second cell in the model, the first and second cells being juxtaposed in geological space and defining a fault face where the first and second cells are intersected by a fault, identifying a first point on the fault face, and calculating slip curves. Respective slip curves originate at the point and extend across the fault in geological space to a respective second point of a plurality of second points. The second points are co-located with the first point in the depositional space. The method includes calculating fault rock properties at the first point based on the slip curves and adjusting the model to include the fault rock properties.