Digital Porous Media Simulation for Relative Permeability
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Solution Overview
Problem
Current methods for estimating relative permeability in porous media, such as laboratory tests and numerical simulations, face challenges including difficulty in replicating downhole conditions, high pressure requirements, long test durations, and inaccuracies in establishing initial conditions like saturation and wettability, especially for tight formations and multi-phase flows.
Innovation Solution
A method involving a three-dimensional digital representation of a porous medium integrated with computational fluid dynamics (CFD) to simulate the flow of wetting and non-wetting fluids, adjusting inlet pressures using a feedback control algorithm to achieve quasi-steady state conditions, and calculating relative permeability versus saturation curves, including data points at low saturation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laboratory tests are used to measure relative permeability, then direct measurement of fluid flow properties is obtained, but the tests require high pressure, long duration, and difficulty in replicating downhole conditions
Solution Approach 1:
The patent creates a three-dimensional digital representation (copy) of the porous medium that replicates its pore structure and flow characteristics. This digital model allows simulation of fluid flow without requiring physical laboratory tests, thereby eliminating the need for high pressure conditions, long test durations, and expensive equipment while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical laboratory testing system with a computational simulation system. Instead of physically forcing fluids through porous media under high pressure in the lab, the invention uses numerical algorithms to simulate multiphase flow behavior, substituting mechanical experimentation with computational modeling to achieve the same measurement objectives.
2Measurement precision
If physical laboratory tests are conducted, then relative permeability data is obtained, but establishing accurate initial conditions like saturation and wettability is difficult
Solution Approach 1:
The digital representation of the porous medium allows precise control and definition of initial conditions in the virtual model. Saturation levels, wettability properties, and fluid distributions can be accurately specified in the simulation without the experimental difficulties of physically establishing these conditions in laboratory tests.
Solution Approach 2:
The patent enables easy modification of initial condition parameters in the digital model. Saturation levels, pressure conditions, and wettability characteristics can be adjusted as input parameters to the simulation, allowing systematic study of different initial states without the complex physical setup required in laboratory experiments.
3Productivity
If numerical simulations are used to estimate relative permeability, then time and cost are reduced, but accuracy in representing real-world conditions may be compromised
Solution Approach 1:
The patent creates a faithful digital copy of the porous medium's three-dimensional pore structure using techniques like X-ray microtomography. This accurate geometric representation ensures that the simulation results reliably reflect real-world flow behavior while maintaining the speed and cost advantages of numerical modeling over physical experiments.
Solution Approach 2:
The simulation incorporates feedback mechanisms where simulation results are compared with available experimental data or theoretical expectations, and the model parameters are adjusted accordingly. This iterative refinement process enhances the reliability of the simulation results while maintaining computational efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for more accurate and efficient estimation of relative permeability, reducing the time and cost of simulations while improving the representation of real-world conditions, enabling better evaluations of porous media productivity and fluid flow characteristics.
Implementation Method 1
periodically adjusting the inlet pressures Pn and Pb using a feedback control algorithm wherein quasi-steady state values for Qn and Qw are achieved
Implementation Method 2
In a porous medium, capillary attraction is determined by the adhesion between a liquid present in the body and the body itself and by the cohesive force of the liquid to itself
Implementation Method 3
capillary attraction is determined by the adhesion between a liquid present in the body and the body itself
Implementation Method 4
capillary attraction is determined by the adhesion between a liquid present in the body and the body itself and by the cohesive force of the liquid to itself
Data Source
Figure 1~2
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AI summary
A method for computing or estimating fractional, multi-phase/multi-component flow through a porous medium employing a 3D digital representation of a porous medium and a computational fluid dynamics method to calculate flow rates, pressures, saturations, internal velocity vectors and other flow parameters is described. The method employs a unique method of introducing non- wetting and wetting fluids into the pores at the inlet face of the 3D digital representation of a porous medium and a novel process control application to achieve quasi-steady state flow at low inlet concentrations of non-wetting fluid. In addition, the method of the present invention reduces the time required to simulate to complete the fluid dynamic calculations. The resulting values of flow of non-wetting fluid, wetting fluid, saturation, and other parameters are used to generate plots of relative permeability imbibition and drainage curves. Computerized systems and programs for performing the method are also provided.