Multi-scale Reservoir Simulation via Saturation Regions
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Solution Overview
Problem
Current reservoir simulators face challenges in efficiently simulating large, fine-scale subsurface reservoir models due to high variability in permeability and complex spatial heterogeneity, leading to significant errors and computational inefficiencies, particularly in capturing fine-scale effects on coarse-scale grids.
Innovation Solution
A multi-scale method is introduced that uses a simulation model with both fine-scale and coarse-scale grids, employing saturation regions defined by predetermined properties to determine fine-scale saturation through various operators, including the Schwarz-Overlap method and prolongation operators based on saturation and velocity changes, allowing for accurate interpolation and extrapolation of physical phenomena across scales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full fine-scale grid simulation is used, then measurement precision and manufacturing precision are improved, but productivity and use of energy deteriorate due to computational cost
Solution Approach 1:
The domain is segmented into multiple coarse-scale blocks, each containing fine-scale cells. The simulation is performed on coarse-scale grids while using prolongation operators to reconstruct fine-scale saturation distributions when needed, thus avoiding the need to simulate all fine-scale cells directly and reducing computational cost while maintaining accuracy where necessary.
Solution Approach 2:
Different regions of the domain are treated differently: in regions where fine-scale details are critical, prolongation operators are used to reconstruct fine-scale saturation from coarse-scale solutions. In other regions, coarse-scale simulation suffices. This localized approach ensures high accuracy where needed while maintaining overall computational efficiency.
2Productivity
If coarse-scale grid is used, then productivity is improved, but measurement precision and manufacturing precision deteriorate due to loss of fine-scale effects
Solution Approach 1:
Prolongation operators serve as intermediaries that transfer information from coarse-scale solutions to fine-scale representations. These operators use basis functions and local permeability characteristics to reconstruct fine-scale saturation distributions, thereby bridging the gap between coarse-scale computational efficiency and fine-scale accuracy requirements.
Solution Approach 2:
The method dynamically adjusts the level of detail based on local conditions. Prolongation operators are applied selectively based on criteria such as saturation changes, velocity changes, and permeability heterogeneity. This parameter-based adaptation allows the simulation to maintain high accuracy in critical regions while using coarser representation elsewhere.
3Productivity
If multi-scale method with prolongation operators is used, then productivity is improved, but device complexity increases due to additional operators and methods
Solution Approach 1:
The prolongation operator framework provides a universal approach that can be applied to different regions and different types of problems. The same basic operator structure is used throughout the domain, with local adaptations based on permeability and saturation characteristics. This universality reduces the need for multiple specialized methods while maintaining flexibility.
Data Source
AI summary
A multi-scale method to efficiently determine the fine-scale saturation arising from multi-phase flow in a subsurface reservoir is disclosed. The method includes providing a simulation model that includes a fine-scale grid defining a plurality of fine-scale cells, and a coarse-scale grid defining a plurality of coarse-scale cells that are aggregates of the fine-scale cells. The coarse-scale cells are partitioned into saturation regions responsive to velocity and/or saturation changes from the saturation front. A fine-scale saturation is determined for each region and the saturation regions are assembled to obtain a fine-scale saturation distribution. A visual display can be output responsive to the fine-scale saturation distribution.