Reservoir Downscaling via Local Flow Simulation and Thresholding
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Solution Overview
Problem
Current methods for downscaling pressures and saturations in reservoir models are imprecise, failing to account for underlying heterogeneities, which affects the accuracy of seismic attribute calculations and reduces the representativeness of geological models.
Innovation Solution
A method involving local flow simulations and iterative calculations on a fine grid to assign pressure and saturation values, using relative permeabilities and porosity data to ensure accurate representation of fluid phases and volume conservation across lithofacies, while considering permeability and porosity thresholds to assign or nullify values in low-permeability zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simple mapping method is used to downscale pressure and saturation values from coarse grid to fine grid, then calculation time is reduced, but precision of seismic attribute calculations deteriorates due to failure to account for underlying heterogeneities
Solution Approach 1:
The patent applies local quality by differentiating between high-permeability zones (where flow occurs and fine-scale detail is critical) and low-permeability zones (where values are constrained or nullified). The method assigns different treatment to different spatial locations: in high-permeability areas, local flow simulations capture heterogeneities, while in low-permeability areas, simple mapping or nullification is sufficient, thus improving precision where needed without unnecessary computational overhead elsewhere.
Solution Approach 2:
The patent changes parameters by introducing permeability and porosity thresholds that control the downscaling process. When permeability or porosity falls below thresholds, the method nullifies or constrains pressure and saturation values rather than performing full local simulations. This parameter-based approach adapts the computational effort to the geological reality, improving seismic attribute precision in permeable zones while maintaining efficiency in impermeable zones.
2Reliability
If local flow simulations are performed on fine grid to account for heterogeneities, then representativeness of geological model is improved, but calculation time increases significantly
Solution Approach 1:
The patent applies local quality by differentiating between high-permeability zones (where flow occurs and fine-scale detail is critical) and low-permeability zones (where values are constrained or nullified). The method assigns different treatment to different spatial locations: in high-permeability areas, local flow simulations capture heterogeneities, while in low-permeability areas, simple mapping or nullification is sufficient, thus improving precision where needed without unnecessary computational overhead elsewhere.
Solution Approach 2:
The patent changes parameters by introducing permeability and porosity thresholds that control the downscaling process. When permeability or porosity falls below thresholds, the method nullifies or constrains pressure and saturation values rather than performing full local simulations. This parameter-based approach adapts the computational effort to the geological reality, improving seismic attribute precision in permeable zones while maintaining efficiency in impermeable zones.
3Measurement precision
If permeability and porosity thresholds are applied to nullify values in low-permeability zones, then accuracy of fluid phase representation is improved, but complexity of the method increases
Solution Approach 1:
The patent changes parameters by introducing permeability and porosity thresholds that control the downscaling process. When permeability or porosity falls below thresholds, the method nullifies or constrains pressure and saturation values rather than performing full local simulations. This parameter-based approach adapts the computational effort to the geological reality, improving seismic attribute precision in permeable zones while maintaining efficiency in impermeable zones.
Solution Approach 2:
The patent applies inversion logic by nullifying fluid phase values in low-permeability zones rather than attempting to simulate them. Instead of trying to accurately represent flow in impermeable zones (which would be computationally expensive and physically meaningless), the method inverts the approach: it assumes no flow occurs in low-permeability zones and sets values to zero or constrains them, thereby simplifying the problem while improving accuracy where it matters.
Data Source
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AI summary
The method involves simulating production data (DP) and pressure and saturation values in each cell of a grid (GG) of a flow model (ME). Pressure and saturation values are assigned to each cell of another grid (GF). Seismic data (DS) are simulated in the latter grid using the pressure and saturation values associated with each cell of the latter grid. The flow model is modified to minimize a difference between the measured production data and the simulated production data and to minimize a difference between the measured seismic data and the simulated seismic data.