Numerical study of Enhanced Oil Recovery in Homogeneous and Heterogeneous porous media by Newtonian, shear-thinning and shear-thickening fluids
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Data
2023-03-24
Autores
Zotelle, Ayrton Cavallini
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Universidade Federal do Espírito Santo
Resumo
The increase of the fraction of extracted oil in petroleum reservoirs is one of the greatest challenges of the petroleum industries, since the oil corresponds to one of the most important energy resources. One of the most useful methods to increase the oil recovery is the injection of a fluid on the reservoir to displace the oil. Immiscible liquid-liquid displacement is a fundamental problem in fluid mechanics and has many applications, like the enhanced oil recovery (EOR). The primary motivation of this work is to evaluate the liquid-liquid displacement in homogeneous and heterogeneous porous media using the Computational Fluid Dynamics (CFD) by Direct Numerical Simulations (DNS). The Basilisk© software is an open source used to solve complex flows, in special those with interfacial phenomena. Therefore, the software was used to run the simulations. The solver uses Cartesian adaptive meshes. Three porous media were evaluated. The homogeneous one, the heterogeneous in which the porosity increases with the y position and the heterogeneous disordered porous medium. The porosity was constant ϕ = 0.7, the range of evaluated viscosity ratio was 0.01 ≤ Nµ ≤ 100 and capillary number 2 × 10−3 ≤ Ca ≤ ∞. The injected fluid has Newtonian, shear-thinning and shear-thickening characteristics with Power-Law index range 0.5 ≤ n ≤ 1.5. It is observed that while the viscosity ratio decreases, the residual oil that remains trapped in the porous media reduce due to the increase of the shear-stress imposed by the injected fluid. When the displacement is dominated by the viscous forces of the recovery fluid, the increase in the interfacial tension makes the interface flat, assisting the displacement. Specially on the porous medium in which the grains have random size and position distribution, the effects of the increment of the interfacial tension differs from the homogeneous porous medium. On the homogeneous porous medium, the fluid passes through all the pores, and the fingering formation is symmetric, but on the heterogeneous disordered porous medium, the high interfacial tension reduces the sweep on minor pores due to the high capillary pressure, so, more of the recovered fluid is left behind. The Pseudo-plasticity was evaluated at low interfacial tension (the viscous forces dominate the flow). It is observed that the shear-thinning fluid recovers more fluid than the Newtonian or shear-thickening fluids, specially at the heterogeneous porous media. Due to the tendency of the injected fluid to pass through the largest pores, the velocity and consequently the shear-rate on minor pores is low, contributing to the increase in the viscosity of the shear-thinning fluid on those regions and also increasing the capability to displace the oil due the high shear-stress and, therefore, the sweep of minor pores increase. The opposite occurs for the shear-thickening fluids. The viscosity reduces at low shear-rates, so that shear-stress also is low and the fluid is inefficient to displace the recovered fluid.
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Palavras-chave
Recuperação de óleo aprimorada , Razão de viscosidade , Número capilar , Fluido de desbaste , Fluido espessante