Fracture Network Partitioning for Reservoir Simulation
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Solution Overview
Problem
Current methods for representing fractures in reservoir models are limited by high computational requirements and memory usage, leading to degradation of simulation models when trying to accurately depict heterogeneity, spatial variability, and anisotropy of fractures, which affects the representation of permeability and fluid flow.
Innovation Solution
A method that partitions the fracture network into a discrete fracture network and a statistical description, allowing for efficient storage and computation by focusing on fractures with significant impact on reservoir connectivity and permeability, using parameters like fracture density, size distribution, and orientation, and deriving petrophysical parameters from these descriptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a discrete fracture network is used to represent all fractures in detail, then the accuracy of fracture representation and permeability calculation is improved, but memory usage and computational time increase significantly
Solution Approach 1:
The fracture network is segmented into two parts: a discrete fracture network representing major fractures with significant impact on connectivity, and a statistical description representing the remaining fracture population. This segmentation allows detailed representation of critical fractures while using compact statistical parameters for the bulk population, reducing memory requirements while maintaining accuracy.
Solution Approach 2:
The invention extracts and represents only the most influential fractures (those with significant impact on reservoir connectivity and permeability) as discrete elements, while extracting the collective effect of less influential fractures into statistical parameters. This extraction approach eliminates the need to store detailed information about all fractures, reducing memory usage while preserving the essential flow characteristics.
2Measurement precision
If a discrete fracture network is used to represent all fractures in detail, then the accuracy of fracture representation and permeability calculation is improved, but computational speed decreases
Solution Approach 1:
By segmenting the fracture representation into discrete major fractures and statistical background fractures, the computational workload is reduced. The flow simulator only needs to explicitly model the discrete fracture network (minority of fractures), while the statistical description provides the background permeability, significantly reducing computation time while maintaining accuracy.
Solution Approach 2:
The invention extracts the collective effect of the majority of fractures into statistical parameters (density, orientation, aperture distribution), eliminating the need to computationally process each individual fracture. This extraction dramatically reduces computational speed requirements while preserving the essential flow behavior.
3Measurement precision
If fractures are represented at fine scale with detailed geometry, then the representation of heterogeneity and spatial variability is improved, but the complexity of the model increases
Solution Approach 1:
The model is segmented into two complementary representations: discrete fracture geometry for major heterogeneities and statistical parameters for background heterogeneity. This segmentation allows detailed representation of spatial variability in fracture distribution while avoiding the complexity of modeling every individual fracture geometry in detail.
Solution Approach 2:
The invention applies local quality by representing fractures with different levels of detail in different locations: discrete geometry is applied locally to major fractures where they control flow, while statistical parameters are used for the background fracture population. This selective approach maintains accuracy where needed while reducing overall model complexity.
Data Source
AI summary
A method of representing and using fractures in a model of a subterranean reservoir is described including the partitioning the fracture network into a discretely modeled part and a remaining statistically described part from a statistical description of all fractures, the determination of the correlation effects caused by fractures with dimensions exceeding dimension of the local grid cells and the determination of petrophysical properties while allowing for arbitrary distribution of fracture orientations, with all three aspects being combinable to improve the modeling of fractures and the simulation of fractured reservoirs.