Multiphase Flow Upscaling Using Upstream Outflow Flux Boundary Condition
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Solution Overview
Problem
Current methods for upscaling multiphase flow in geologic models face challenges in accurately preserving dynamic quantities like recovery factors and production performance, particularly due to the simplification of small-scale petrophysical heterogeneity, leading to inefficiencies in sweep efficiency and production predictions.
Innovation Solution
A new local boundary condition, the Upstream Outflow Flux Boundary Condition (UOFBC), is introduced, which defines a local domain with specific boundary conditions to simulate fluid flow through concatenated, upstream, and downstream coarse grid domains, allowing for the generation of dynamic pseudo-functions that accurately represent relative permeability without overestimating saturation, thus improving the accuracy of fine-scale simulation reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simple static calculation of coarse scale petrophysical properties is used, then computational cost is reduced, but recovery factors and production performance are not preserved accurately
Solution Approach 1:
The patent applies dynamics by transitioning from static upscaling methods to dynamic pseudo-function methods. The pseudo-functions are generated through time-dependent flow simulations that capture the evolution of saturation and flow rates, allowing the upscaling to adapt to changing flow conditions rather than relying on fixed static properties
Solution Approach 2:
The patent changes parameters by introducing dynamic pseudo-functions that depend on saturation and other flow parameters. Instead of using constant upscaled properties, the method generates parameter-dependent pseudo-functions that adjust according to the actual flow state, improving accuracy while maintaining computational feasibility
2Reliability
If fine scale models with detailed geological description are used, then hydrocarbon in-place and reserves are preserved, but computational time becomes prohibitive
Solution Approach 1:
The patent applies segmentation by dividing the computational domain into coarse gridblocks and using local flow simulations within representative elementary volumes (REV) to generate pseudo-functions. This segmentation allows the model to capture fine-scale effects locally while using a coarse grid for the overall simulation, reducing total computational time
Solution Approach 2:
The patent introduces pseudo-functions as intermediaries between fine-scale geological properties and coarse-scale flow simulation. These pseudo-functions act as mediators that translate detailed petrophysical properties into effective parameters for coarse grids, preserving fine-scale information without requiring fine-scale computational resources
3Device complexity
If small scale petrophysical heterogeneity is simplified during upscaling, then model complexity is reduced, but sweep efficiency is miscalculated
Solution Approach 1:
The patent applies preliminary action by pre-generating pseudo-functions through local flow simulations that capture the effects of small-scale heterogeneity. These pseudo-functions are prepared in advance and then used in the coarse-scale simulation to account for heterogeneity effects without explicitly modeling the fine-scale structure, maintaining sweep efficiency accuracy while reducing model complexity
Data Source
AI summary
A method of multiphase flow upscaling of a fine scale geologic model. A local domain is defined from the fine scale geologic model. The local domain includes adjacent upstream and downstream coarse grid domains and a concatenated domain adjacent the upstream coarse grid domain. A coarse grid interface is defined between the upstream coarse grid domain and the downstream coarse grid domain. Boundary conditions are imposed on various faces of the components of the local domain. Fluid flow is simulated through the local domain for a plurality of time steps until the local domain is completely flooded. A fine scale solution of saturation and flow rate of individual fluid phases across the coarse grid interface is recorded at each time step. A pseudo-function is constructed by post-processing results of the simulation of fluid flow. The fine scale geologic model is upscaled to a coarse scale geologic model using the pseudo-function.