Print Email Facebook Twitter Fluid Conductivity of Steady Two-Phase Flow in a 2D Micromodel Title Fluid Conductivity of Steady Two-Phase Flow in a 2D Micromodel: Analysis of a Representative 2D Percolation Model Author Hadjisotiriou, George (TU Delft Civil Engineering and Geosciences) Contributor Rossen, W.R. (mentor) Dieudonné, A.A.M. (graduation committee) Degree granting institution Delft University of Technology Date 2020-07-05 Abstract Foams are used in reservoir engineering for enhanced oil recovery, CO2 sequestration and environmental remediation of aquifers and soils. One of the main mechanisms for foam generation at steady state is Roof snap-off. In some cases, mechanistic models of Roof snap off, based on observations from 2D micromodels are used for reservoir simulation. The main problem with these experiments is in their 2D nature. Two-phase flow within a 2D medium requires that the fluids paths cross and compete for pore occupancy. This virtually ensures fluctuating pore occupancy and therefore puts into question the applicability of 2D mechanistic models for steady state foam generation in 3D media. Two-phase flow in a micromodel is analyzed with a lattice percolation model in order to determine under what conditions steady two-phase flow can be achieved. The gas network is established with bond percolation and liquid is allowed to flow across the sample with the help of liquid bridges. These liquid bridges enable the liquid to cross gas-occupied pore throats without snap-off. The calculated attribute for the gas and liquid networks is equivalent resistance, ΔP/Q. For this a new unit for hydraulic resistivity was used and is equal to the fluid viscosity divided by the pore radius to the third power, H = μ/R3. The equivalent resistance of the gas and liquid networks are found by applying rules from linear circuits of electrical resistances. Solutions for the equivalent resistivity of the gas network are calculated with the node elimination method and Kirchhoff’s solution for a random network of resistances. The liquid network’s conductivity is calculated as the sum of path resistances in parallel and is a theoretical maximum. The gas and liquid conductivity of nine pre-existing 16x16 networks from Holstvoogd(2020) are reevaluated and, in addition, twelve new samples of size 32x32 are evaluated. Functionally, the model’s behavior is as follows: gas conductivity is inversely proportional and liquid conductivity is proportional to the occupation threshold. It is found that the gas conductivity is a function of tortuosity and number of parallel flow loops. Conductivity decreases with increased tortuosity and increases with number of parallel flow paths. The ratio of liquid and gas conductivity for the twelve 32x32 models is calculated. When adjusted for gas viscosities of supercritical CO2 and Nitrogen gas it is found that it is in the order of 10-3 to 10-4. Therefore, it has been determined that it is practically impossible to achieve steady two-phase flow without fluctuating pore occupancy. Subject FoamMicromodelNetwork conductivityKirchoff's solutionNode eliminationliquid bridging To reference this document use: http://resolver.tudelft.nl/uuid:41d07bf0-d520-4e87-932a-bb2049486daf Part of collection Student theses Document type bachelor thesis Rights © 2020 George Hadjisotiriou Files PDF Fluid_Conductivity_of_Ste ... tiriou.pdf 3 MB Close viewer /islandora/object/uuid:41d07bf0-d520-4e87-932a-bb2049486daf/datastream/OBJ/view