Статті в журналах з теми "Dual-scale flow simulation"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Dual-scale flow simulation.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Dual-scale flow simulation".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Li, Hangyu, Jeroen C. Vink, and Faruk O. Alpak. "A Dual-Grid Method for the Upscaling of Solid-Based Thermal Reactive Flow, With Application to the In-Situ Conversion Process." SPE Journal 21, no. 06 (June 2, 2016): 2097–111. http://dx.doi.org/10.2118/173248-pa.
Анотація:
Summary Thermal-reactive compositional-flow simulation in porous media is essential to model thermal-oil-recovery processes for extraheavy-hydrocarbon resources, and an example is the in-situ conversion process (ICP) developed by Shell for oil-shale production. Computational costs can be very high for such a complex system, which makes direct fine-scale simulations prohibitively time-consuming for large field-scale applications. This motivates the use of coarse grids for thermal-reactive compositional-flow simulation. However, significant errors are introduced by use of coarse-scale models without carefully computing the appropriate coarse parameters. In this paper, we develop an innovative dual-grid method to effectively capture the fine-scale reaction rates in coarse-scale ICP-simulation models. In our dual-grid method, coupled thermal-reactive compositional-flow equations are solved only on the coarse scale, with the kinetic parameters (frequency factors) calculated on the basis of fine-scale computations, such as temperature downscaling and fine-scale reaction-rate calculation. A dual-grid treatment for the heater-well model is also developed with coarse-scale heater-well indices calculated on the basis of fine-scale well results. The dual-grid heater-well treatment is able to provide accurate heater temperatures. The newly developed dual-grid method is applied to realistic cross-sectional ICP-pattern models with a vertical production well and multiple horizontal heater wells operated subject to fixed and time-varying heater powers. It is shown that the dual-grid model delivers results that are in close agreement with the fine-scale reference results for all quantities of interest. Despite the fact that the dual-grid method is implemented at the simulation-deck level, by use of the flexible scripting and monitor functionalities of our proprietary simulation package, significant computational improvements are achieved for all cases considered.
2
Tchelepi, Hamdi A., Patrick Jenny, Seong Hee Lee, and Christian Wolfsteiner. "Adaptive Multiscale Finite-Volume Framework for Reservoir Simulation." SPE Journal 12, no. 02 (June 1, 2007): 188–95. http://dx.doi.org/10.2118/93395-pa.
Анотація:
Summary A multiscale finite-volume (MSFV) framework for reservoir simulation is described. This adaptive MSFV formulation is locally conservative and yields accurate results of both flow and transport in large-scale highly heterogeneous reservoir models. IMPES and sequential implicit formulations are described. The algorithms are sensitive to the specific characteristics of flow (i.e., pressure and total velocity) and transport (i.e., saturation). To compute the fine-scale flow field, two sets of basis functions - dual and primal - are constructed. The dual basis functions, which are associated with the dual coarse grid, are used to calculate the coarse scale transmissibilities. The fine-scale pressure field is computed from the coarse grid pressure via superposition of the dual basis functions. Having a locally conservative fine scale velocity field is essential for accurate solution of the saturation equations (i.e., transport). The primal basis functions, which are associated with the primal coarse grid, are constructed for that purpose. The dual basis functions serve as boundary conditions to the primal basis functions. To resolve the fine-scale flow field in and around wells, a special well basis function is devised. As with the other basis functions, we ensure that the support for the well basis is local. Our MSFV framework is designed for adaptive computation of both flow and transport in the course of a simulation run. Adaptive computation of the flow field is based on the time change of the total mobility field, which triggers the selective updating of basis functions. The key to achieving scalable (efficient for large problems) adaptive computation of flow and transport is the use of high fidelity basis functions with local support. We demonstrate the robustness and computational efficiency of the MSFV simulator using a variety of large heterogeneous reservoir models, including the SPE 10 comparative solution problem.
3
Imbert, Mathieu, Sebastien Comas-Cardona, Emmanuelle Abisset-Chavanne, and David Prono. "Introduction of intra-tow release/storage mechanisms in reactive dual-scale flow numerical simulations." Journal of Composite Materials 53, no. 1 (June 22, 2018): 125–40. http://dx.doi.org/10.1177/0021998318780498.
Анотація:
Classical dual-scale reactive simulations of the RTM process assume permanent intra-tow resin storage in the saturated domain. However, recent experimental investigations revealed that permanent storage is occurring only in a limited volume of the tows. In the remaining volume, fluid is released in the channels with a rate that depends on the architecture of the textile and on the fiber volume fraction. Based on experimental observations, a new model is proposed to refine the simulation of the high speed reactive RTM process: a simplified microstructural model is used to enable permanent and partial transient storage within the tows. Additionally, a new sink term is proposed to reproduce the kinetics of the convective tow-channel fluid exchanges in the saturated domain. After a state of the art on dual-scale and reactive flow, the experimental inputs of the study are presented. The new model is then introduced, validated and characterized using the experimental inputs. Additionally, the influence of the release mechanisms on a reactive dual-scale injection is estimated by conducting comparative single-scale, and dual-scale simulations with transient or permanent storage. The new model has been demonstrated to be appropriate to reproduce accurately the release mechanisms, and simulations reveal the interest of taking these release mechanisms into account to simulate reactive dual-scale injections with an increased accuracy.
4
Ye, Xin, and Shi Lin Yan. "The Simulation of the Un-Saturated Flow in the Dual-Scale Porous Media under Constant Flow Rate." Advanced Materials Research 753-755 (August 2013): 2747–51. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2747.
Анотація:
Considering the un-saturated in the experiment, the purpose of this paper is achieving a simple 1d molds unsaturated simulation of the filling process through the compiled software pore-flow and compare the single-scale result with the dual-scale result.
5
Lu, Gang, Liping He, Dachuan Chen, and Wenjun Li. "Smoothed particle hydrodynamics simulation of dual-scale flow during resin transfer molding." Journal of Reinforced Plastics and Composites 36, no. 19 (June 13, 2017): 1431–38. http://dx.doi.org/10.1177/0731684417709950.
6
Haji, Hind, Abdelghani Saouab, and Yasir Nawab. "Simulation of coupling filtration and flow in a dual scale fibrous media." Composites Part A: Applied Science and Manufacturing 76 (September 2015): 272–80. http://dx.doi.org/10.1016/j.compositesa.2015.06.004.
7
Rios, Victor S., Luiz O. S. Santos, and Denis J. Schiozer. "Upscaling Technique for Highly Heterogeneous Reservoirs Based on Flow and Storage Capacity and the Lorenz Coefficient." SPE Journal 25, no. 04 (March 5, 2020): 1981–99. http://dx.doi.org/10.2118/200484-pa.
Анотація:
Summary Field-scale representation of highly heterogeneous reservoirs remains a challenge in numerical reservoir simulation. In such reservoirs, detailed geological models are important to properly represent key heterogeneities. However, high computational costs and long simulation run times make these detailed models unfeasible to use in dynamic evaluations. Therefore, the scaling up of geological models is a key step in reservoir-engineering studies to reduce computational time. Scaling up must be carefully performed to maintain integrity; both truncation errors and the smoothing of subgrid heterogeneities can cause significant errors. This work evaluates the latter—the effect of averaging small-scale heterogeneities in the upscaling process—and proposes a new upscaling technique to overcome the associated limitations. The technique is dependent on splitting the porous media into two levels guided by flow- and storage-capacity analysis and the Lorenz coefficient (LC), both calculated with static properties (permeability and porosity) from a fine-scale reference model. This technique allows the adaptation of a fine highly heterogeneous geological model to a coarse-scale simulation model in a dual-porosity/dual-permeability (DP/DP) approach and represents the main reservoir heterogeneities and possible preferential paths. The new upscaling technique is applied to different reservoir-simulation models with water injection and immiscible gas injection as recovery methods. In deterministic and probabilistic studies, we show that the resulting coarse-scale dual-permeability models are more accurate and can better reproduce the fine-scale results in different upscaling ratios (URs), without using any simulation results of the reference fine-scale simulation models, as some of the current alternative upscaling methods do.
8
Barnhart, Cynthia. "Dual-ascent methods for large-scale multicommodity flow problems." Naval Research Logistics 40, no. 3 (April 1993): 305–24. http://dx.doi.org/10.1002/1520-6750(199304)40:3<305::aid-nav3220400303>3.0.co;2-4.
9
Yashiro, Shigeki, Daichi Nakashima, Yutaka Oya, Tomonaga Okabe, and Ryosuke Matsuzaki. "Particle simulation of dual-scale flow in resin transfer molding for process analysis." Composites Part A: Applied Science and Manufacturing 121 (June 2019): 283–88. http://dx.doi.org/10.1016/j.compositesa.2019.03.038.
10
Yan, Shi Lin, Hang Lu, Hua Tan, and Zhong Qi Qiu. "Microscopic Analysis of Flow and Prediction of Effective Permeability for Dual-Scale Porous Fiber Fabrics." Advanced Materials Research 97-101 (March 2010): 1776–81. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.1776.
Анотація:
In this paper, the permeability of fiber fabric used in liquid composite molding (LCM) is predicted by the method of numerical simulation. The three-dimensional finite element model of unit cell representing the periodic micro-structure of a plaid is established. In the process of numerical simulation, each fiber bundle in unit cell is treated as a porous medium. Stokes equation and Darcy's law are employed to model the saturated flow between the fiber bundles and the saturated flow in the fiber bundle, respectively. Steady state flow of the finite element model of unit cell is simulated. The effective permeability of the plaid is obtained from the postprocessing of the simulation results by using Darcy's law.
11
Imbert, Mathieu, Emmanuelle Abisset-Chavanne, Sébastien Comas-Cardona, and David Prono. "Efficient dual-scale flow and thermo-chemo-rheological coupling simulation during on-line mixing resin transfer molding process." Journal of Composite Materials 52, no. 3 (June 8, 2017): 313–30. http://dx.doi.org/10.1177/0021998317706536.
Анотація:
Simulation tools are required to ease the determination of the optimal process parameters and injection strategy of short cycle resin transfer molding (RTM). The developed finite element method/volume of fluid numerical tool aims to simulate accurately and efficiently the flow of a reactive resin mixed on-line in a dual-scale porous reinforcement during the resin transfer molding process. A macroscopic mesh deals with the flow inside of the channels of the reinforcement while a representative microstructure associated to each element allows reproducing both the unsaturated area and the intra-tow resin storage. Degree of cure, temperature, and viscosity are updated and transported at each time step, both in the channels and in the tows of the fabric using advection equations and sink and source terms for inter-scale exchanges. A new flexible approach based on the textile’s geometry defines automatically the representative microstructure associated to each macroscopic element depending on its size and shape. Additionally, tow saturation is simplified under the assumption of high-speed injection to a sum of one-dimensional transverse tow saturation problems, which reduces the computational cost of the simulation. Convergence tests have highlighted the ability for the simulation tool to treat with an equivalent degree of accuracy a saturation problem with elements exhibiting element sizes three times smaller to three times bigger than the length of the unsaturated area. Significant computation time reductions have also been noticed when large elements were used. Finally thermo-chemo-rheological coupled simulations have been conducted, highlighting the importance of taking the dual-scale effect into account when simulating reactive injections with on-line mixing.
12
Lee, Yong Jing, Shi Lin Yan, Xin Ye, and Zhong Jiang Feng. "The Isothermal Simulation of the Un-Saturated Flow in the Dual-Scale Porous Media." Advanced Materials Research 652-654 (January 2013): 143–47. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.143.
Анотація:
Most of the mold-filling simulation theories for RTM were based on Darcy law and combined with mass conservation equation. Considering the unsaturated region in the experiment, the followings have been done in this paper: (1) first, explaining this un-saturated phenomenon as a sink effect, and amending the saturated filling mold by introducing a sink term to the mass constant equation; (2) second, achieving a simple 1d mold’s unsaturated simulation of the filling process through the compiled software pore-flow.
13
Haji, Hind, and Abdelghani Saouab. "Numerical Modeling of the Flow of Particle-Filled Resin through a Dual Scale Fibrous Media." Advanced Materials Research 1099 (April 2015): 44–51. http://dx.doi.org/10.4028/www.scientific.net/amr.1099.44.
Анотація:
We present numerical simulation of particle filled resin flow through a fibrous media taking into account dual scale porosity in LCM (Liquid Composite Molding) processes. During the flow, a strong interaction between the particle motion and the fluid flow takes place at the porous medium wall or at the fiber bundle surface. A model is developed to describe the particle retention and filtration in the porous media. In this study, the Stokes-Darcy equation is solved to describe the resin flow in a mesoscopic scale. The particle retention mechanism is extensively studied taking into account the influences from such parameters as size and concentration of particles. The particle filled resin flow through a fibrous media simulation is performed to demonstrate the effect on the retention and filtration mechanism during the composites manufacturing by LCM processes.
14
Zhang, Wei, Zong Dai, Bin Gong, Yahui Wang, Xiaolin Zhang, and Xiao Chen. "Application of an Accurate and Efficient Modeling Approach to a Multiscale Fractured Reservoir in South China Sea." Geofluids 2021 (September 23, 2021): 1–8. http://dx.doi.org/10.1155/2021/9933155.
Анотація:
Carbonate reservoirs in the South China Sea mostly contain natural fractures with various length scales and different intensities, which causes great challenges in efficient reservoir modeling and flow simulation. Existing efforts based on dual-porosity and dual-permeability models could not reflect the characteristics of production data in certain wells. To accurately and efficiently characterize multiscale fractures, a hybrid fracture characterization method is proposed. Firstly, fractures are divided into two types according to the geometrical size and interpretation approach. Then, small-scale fractures, characterized mainly by image log interpretations, are modeled by the traditional dual-porosity/dual-permeability (DP) method. And large-scale fractures, which are characterized by seismic interpretations and dominate the flow regime, are modeled by the embedded discrete fracture method (EDFM) to achieve both accuracy and efficiency. Lastly, transmissibilities among these three types of grid mediums are calculated to generate the hybrid DP+EDFM model for flow simulation. The proposed approach is applied to a carbonate, fractured reservoir in the South China Sea. The overall procedure is fast and reliable, and water cut matches of both field and specific wells are dramatically improved. Comparing the simulation results with the conventional DP model, the proposed approach yields much more accurate predictions on rapid water breakthrough and high water cut in fractured reservoirs.
15
Chen, Xiao Jiang, Si Jia Guo, Wen Yan Yan, and Shi Lin Yan. "The Resin Radial Flow Numerical Simulation in Dual-Scale Porous Fibre Media at Constant Pressure." Advanced Materials Research 756-759 (September 2013): 44–48. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.44.
Анотація:
In this paper, setting up a mathematical model about LCM process based on the theory, which contains a sink term in the mass balance equation of the fluid dynamics. In two-dimensional mold, the finite element/control volume method is used to simulate the flow front and pressure distribution of the flowing resin in single-scale and dual-scale porous media at constant pressure.
16
Ding, Yu, Remy Basquet, and Bernard Bourbiaux. "Upscaling Fracture Networks for Simulation of Horizontal Wells Using a Dual-Porosity Reservoir Simulator." SPE Reservoir Evaluation & Engineering 9, no. 05 (October 1, 2006): 513–20. http://dx.doi.org/10.2118/92774-pa.
Анотація:
Summary One difficulty in fracture upscaling for field-scale dual-porosity reservoir simulation is the determination of equivalent gridblock fracture permeability, which depends on the type of boundary conditions imposed on the discrete-fracture-network (DFN) simulation. Actually, classical upscaling procedures usually are based on linearly varying pressure boundary conditions, which cannot capture the near-well flow behavior. As a result, the well productivity calculated by a dual-porosity flow simulator can be very different from that calculated on a DFN model. This paper proposes a near-well fracture-upscaling procedure based on the geological DFN model to improve the accuracy of well productivity in fractured-reservoir simulators. This procedure enables us to represent the actual flow through the fractures and the exchanges between matrix and fractures in the well vicinity. On the basis of the computed near-well flow pattern, equivalent fracture transmissibilities as well as numerical well indices are determined and assigned to the gridblocks of the dual-porosity reservoir simulator. The reliability and necessity of using the near-well upscaling procedure are demonstrated by examples. Introduction Advanced characterization methodologies are now able to provide realistic models of geological fracture networks (Cacas et al. 2001). In addition, production logging and transient well tests can be simulated with DFN models to validate the geological fracture-network geometry and calibrate the hydraulic properties of fractures (Sarda et al. 2002). However, because of computational limitations, the complex geological DFN model cannot be used straightforwardly to simulate a multiphase-flow production scenario at field scale (Bourbiaux et al. 2002). For such simulations, a dual-porosity reservoir simulator is typically used. The dual-porosity reservoir model, using large gridblocks to discretize the whole reservoir, is a conceptual representation of the actual geology of the fractured medium. The flow properties of the fracture network are then homogenized on gridblocks through upscaling procedures. The upscaling of fracture properties is the problem of translating the geological and hydraulic description of fracture networks into reservoir-simulation parameters. The dual-porosity model requires the determination of equivalent fracture permeability and equivalent matrix-block dimensions or shape factors (Bourbiaux et al. 1997; Sarda et al. 1997). This paper discusses methodologies for upscaling the permeability of a fracture network, especially in the vicinity of the well. Upscaling of fracture permeability has been studied extensively. The commonly used method is numerical, based on flow simulation on a model of the actual fracture network with specific boundary conditions to compute an equivalent gridblock permeability (Sarda et al. 1997). Other methods were also developed; for example, Oda (1985) proposed an analytical equation to calculate the fracture-permeability tensor, and Lough et al. (1997) presented an approach using the boundary-element method, which integrates the contribution of matrix in the equivalent permeability of the fractured medium. When using a numerical approach to determine the equivalent permeability of a fracture network, the upscaled result depends on the type of boundary conditions imposed in the flow simulation. Actually, classical upscaling procedures are usually based on flow simulation in a parallelepipedic model with linear-type pressure boundary conditions, which cannot capture the near-well flow behavior. As a result, the well productivity calculated by a dual-porosity flow simulator can be very different from that calculated on a near-wellbore DFN model.
17
Chen, Xiao Jiang, Wei Chen, Yi Xing Chen, and Yu Hua Zhang. "The Numerical Simulation of LCM in Dual-Scale Porous Fiber Medium Flow at Constant Pressure." Applied Mechanics and Materials 543-547 (March 2014): 41–45. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.41.
Анотація:
In this paper, setting up a mathematical mold for LCM filling process, which contains sink term. The control volume/finite element method is used to build finite element equation for three-dimensional preforms pressure field and get the solution. Numerical simulation of pressure field that resin flowing in three-dimensional dual-scale porous medium is achieved.
18
Li, Chen, Arthur Cantarel, and Xiaojing Gong. "A study on resin infusion and effects of reinforcement structure at dual scales by a quasi-realistic numerical simulation method." Journal of Composite Materials 54, no. 27 (May 25, 2020): 4157–71. http://dx.doi.org/10.1177/0021998320926707.
Анотація:
In this article, we propose a random fiber configuration method to set up quasi-realistic geometric models of the fibrous tow in reinforcement. Finite element method is applied to simulate the injection of resin at dual scales (both intra and inter tows, 2D and 3D models). Permeabilities of dual scales in three directions (in horizonal, vertical and longitudinal directions) are also explored. The influence of variant structure parameters on the permeability is discussed in the meantime. Flow front tracking considering surface tension effect based on the dual-scale model is carried out to predict resin flow through the fibrous reinforcement.
19
Sun, Hao, Adwait Chawathé, Hussein Hoteit, Xundan Shi, and Lin Li. "Understanding Shale Gas Flow Behavior Using Numerical Simulation." SPE Journal 20, no. 01 (January 2, 2015): 142–54. http://dx.doi.org/10.2118/167753-pa.
Анотація:
Summary Shale gas has changed the energy equation around the world, and its impact has been especially profound in the United States. It is now generally agreed that the fabric of shale systems comprises primarily organic matter, inorganic material, and natural fractures. However, the underlying flow mechanisms through these multiporosity and multipermeability systems are poorly understood. For instance, debate still exists about the predominant transport mechanism (diffusion, convection, and desorption), as well as the flow interactions between organic matter, inorganic matter, and fractures. Furthermore, balancing the computational burden of precisely modeling the gas transport through the pores vs. running full reservoir scale simulation is also contested. To that end, commercial reservoir simulators are developing new shale gas options, but some, for expediency, rely on simplification of existing data structures and/or flow mechanisms. We present here the development of a comprehensive multimechanistic (desorption, diffusion, and convection), multiporosity (organic materials, inorganic materials, and fractures), and multipermeability model that uses experimentally determined shale organic and inorganic material properties to predict shale gas reservoir performance. Our multimechanistic model takes into account gas transport caused by both pressure driven convection and concentration driven diffusion. The model accounts for all the important processes occurring in shale systems, including desorption of multicomponent gas from the organics' surface, multimechanistic organic/inorganic material mass transfer, multimechanistic inorganic material/fracture network mass transfer, and production from a hydraulically fractured wellbore. Our results show that a dual porosity, dual permeability (DPDP) model with Knudsen diffusion is generally adequate to model shale gas reservoir production. Adsorption can make significant contributions to original gas in place, but is not important to gas production because of adsorption equilibrium. By comparing triple porosity, dual permeability; DPDP; and single porosity, single permeability formulations under similar conditions, we show that Knudsen diffusion is a key mechanism and should not be ignored under low matrix pressure (Pematrix) cases, whereas molecular diffusion is negligible in shale dry gas production. We also guide the design of fractures by analyzing flow rate limiting steps. This work provides a basis for long term shale gas production analysis and also helps define value adding laboratory measurements.
20
Nguyen, Philipp T. L., Juan C. Uribe, Imran Afgan, and Dominique R. Laurence. "A Dual-Grid Hybrid RANS/LES Model for Under-Resolved Near-Wall Regions and its Application to Heated and Separating Flows." Flow, Turbulence and Combustion 104, no. 4 (October 23, 2019): 835–59. http://dx.doi.org/10.1007/s10494-019-00070-8.
Анотація:
Abstract A hybrid RANS/LES model for high Reynolds number wall-bounded flows is presented, in which individual Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES) are computed in parallel on two fully overlapping grids. The instantaneous, fluctuating subgrid-scale stresses are blended with a statistical eddy viscosity model in regions where the LES grid is too coarse. In the present case, the hybrid model acts as a near-wall correction to the LES, while it retains the fluctuating nature of the flow field. The dual computation enables the LES to be run on isotropic grids with very low wall-normal and wall-parallel resolution, while the auxiliary RANS simulation is conducted on a wall-refined high-aspect ratio grid. Running distinct, progressively corrected simulations allows a clearer separation of the mean and instantaneous flow fields, compliant with the fundamentally dissimilar nature of RANS and LES. Even with the wall-nearest grid point lying far in the logarithmic layer, velocity and temperature predictions of a heated plane channel flow are corrected. For a periodic hill flow, the dual-grid system improves the boundary layer separation and velocity field prediction both for a constant-spaced and a wall-refined LES grid.
21
He, Xiansong, Yi Liu, and Wangqing Wu. "A General and Efficient Approach for the Dual-Scale Infiltration Flow Balancing in In Situ Injection Molding of Continuous Fiber Reinforced Thermoplastic Composites." Polymers 13, no. 16 (August 12, 2021): 2689. http://dx.doi.org/10.3390/polym13162689.
Анотація:
In situ injection molding of continuous fiber reinforced thermoplastic composites is challenged by unbalanced dual-scale infiltration flow due to the pronounced capillary effect. In this paper, a general and efficient approach was proposed for dual-scale infiltration flow balancing based on numerical simulation. Specifically, Stokes and Brinkman equations were used to describe the infiltration flow in inter- and intra-fiber bundles. In particular, capillary pressure drop was integrated in the Brinkmann equation to consider the capillary effect. The infiltration flow front is tracked by the level set method. Numerical simulation and experimental results indicate that the numerical model can accurately demonstrate the unbalanced infiltration flow in inter- and intra-fiber bundles caused by the changes of the injection rate, the resin viscosity, the injection rate, the fiber volume fraction and the capillary number. In addition, the infiltration flow velocity in inter- and intra-fiber bundles can be efficiently tuned by the capillary number, which is mainly determined by the injection rate for a specified resin system. The optimal capillary numbers obtained by simulation and experiment are 0.022 and 0.026, which are very close to each other. Finally, one-dimensional in situ injection molding experiments with constant injection pressure were conducted to prepare fiber reinforced polymerized cyclic butylene terephthalate composite laminate with various flow rates along the infiltration direction. The experimental results confirmed that the lowest porosity and the highest interlaminar shear strength of the composite can only be obtained with the optimized capillary number, which is basically consistent with the simulation results.
22
Li, Xin, Xiang Li, Dongxiao Zhang, and Rongze Yu. "A Dual-Grid, Implicit, and Sequentially Coupled Geomechanics-and-Composition Model for Fractured Reservoir Simulation." SPE Journal 25, no. 04 (June 10, 2020): 2098–118. http://dx.doi.org/10.2118/201210-pa.
Анотація:
Summary In the development of fractured reservoirs, geomechanics is crucial because of the stress sensitivity of fractures. However, the complexities of both fracture geometry and fracture mechanics make it challenging to consider geomechanical effects thoroughly and efficiently in reservoir simulations. In this work, we present a coupled geomechanics and multiphase-multicomponent flow model for fractured reservoir simulations. It models the solid deformation using a poroelastic equation, and the solid deformation effects are incorporated into the flow model rigorously. The noticeable features of the proposed model are it uses a pseudocontinuum equivalence method to model the mechanical characteristics of fractures; the coupled geomechanics and flow equations are split and sequentially solved using the fixed-stress splitting strategy, which retains implicitness and exhibits good stability; and it simulates geomechanics and compositional flow, respectively, using a dual-grid system (i.e., the geomechanics grid and the reservoir-flow grid). Because of the separation of the geomechanics part and the flow part, the model is not difficult to implement based on an existing reservoir simulator. We validated the accuracy and stability of this model through several benchmark cases and highlighted the practicability with two large-scale cases. The case studies demonstrate that this model is capable of considering the key effects of geomechanics in fractured-reservoir simulation, including matrix compaction, fracture normal deformation, and shear dilation, as well as hydrocarbon phase behavior. The flexibility, efficiency, and comprehensiveness of this model enable a more realistic geocoupled reservoir simulation.
23
Balogun, Adetayo S., Hossein Kazemi, Erdal Ozkan, Mohammed Al-kobaisi, and Benjamin Ramirez. "Verification and Proper Use of Water-Oil Transfer Function for Dual-Porosity and Dual-Permeability Reservoirs." SPE Reservoir Evaluation & Engineering 12, no. 02 (April 14, 2009): 189–99. http://dx.doi.org/10.2118/104580-pa.
Анотація:
Summary Accurate calculation of multiphase fluid transfer between the fracture and matrix in naturally fractured reservoirs is a very crucial issue. In this paper, we will present the viability of the use of a simple transfer function to accurately account for fluid exchange resulting from capillary and gravity forces between fracture and matrix in dual-porosity and dual-permeability numerical models. With this approach, fracture- and matrix-flow calculations can be decoupled and solved sequentially, improving the speed and ease of computation. In fact, the transfer-function equations can be used easily to calculate the expected oil recovery from a matrix block of any dimension without the use of a simulator or oil-recovery correlations. The study was accomplished by conducting a 3-D fine-grid simulation of a typical matrix block and comparing the results with those obtained through the use of a single-node simple transfer function for a water-oil system. This study was similar to a previous study (Alkandari 2002) we had conducted for a 1D gas-oil system. The transfer functions of this paper are specifically for the sugar-cube idealization of a matrix block, which can be extended to simulation of a match-stick idealization in reservoir modeling. The basic data required are: matrix capillary-pressure curves, densities of the flowing fluids, and matrix block dimensions. Introduction Naturally fractured reservoirs contain a significant amount of the known petroleum hydrocarbons worldwide and, hence, are an important source of energy fuels. However, the oil recovery from these reservoirs has been rather low. For example, the Circle Ridge Field in Wind River Reservation, Wyoming, has been producing for 50 years, but the oil recovery is less than 15% (Golder Associates 2004). This low level of oil recovery points to the need for accurate reservoir characterization, realistic geological modeling, and accurate flow simulation of naturally fractured reservoirs to determine the locations of bypassed oil. Reservoir simulation is the most practical method of studying flow problems in porous media when dealing with heterogeneity and the simultaneous flow of different fluids. In modeling fractured systems, a dual-porosity or dual-permeability concept typically is used to idealize the reservoir on the global scale. In the dual-porosity concept, fluids transfer between the matrix and fractures in the grid-cells while flowing through the fracture network to the wellbore. Furthermore, the bulk of the fluids are stored in the matrix. On the other hand, in the dual-permeability concept, fluids flow through the fracture network and between matrix blocks. In both the dual-porosity and dual-permeability formulations, the fractures and matrices are linked by transfer functions. The transfer functions account for fluid exchanges between both media. To understand the details of this fluid exchange, an elaborate method is used in this study to model flow in a single matrix block with fractures as boundaries. Our goal is to develop a technique to produce accurate results for use in large-scale modeling work.
24
Li, Xiao Lin, Guang Wei Meng, Li Ming Zhou, and Feng Li. "Global Multiscale Finite Element Method for Flow in Fractured Media." Advanced Materials Research 945-949 (June 2014): 1007–10. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.1007.
Анотація:
Numerical simulation in fractured media is challenging because of the complex microstructure and the coupled fluid flow in porous and fractured media. In this paper, we have extended the global multiscale finite element method (GMsFEM) to study the fluid flow in fractured media with a dual porosity model. By using the fine-scale solution at t=0 to determine the boundary conditions of the basis function, local and nonlocal informations are reflected in the basis functions. As a result, an accurate solution can be achieved in the coarse scale. Numerical example demonstrate that the solution of GMsFEM is highly consistent with the fine-scale solution of FEM. Furthermore, GMsFEM provides a great computational efficiency.
25
Cimini, M., E. Martelli, and M. Bernardini. "Numerical Analysis of Side-loads Reduction in a Sub-scale Dual-bell Rocket Nozzle." Flow, Turbulence and Combustion 107, no. 3 (January 28, 2021): 551–74. http://dx.doi.org/10.1007/s10494-021-00243-4.
Анотація:
AbstractA calibrated delayed detached eddy simulation of a sub-scale cold-gas dual-bell nozzle flow at high Reynolds number and in sea-level mode is carried out at nozzle pressure ratio NPR = 45.7. In this regime the over-expanded flow exhibits a symmetric and controlled flow separation at the inflection point, that is the junction between the two bells, leading to the generation of a low content of aerodynamic side loads with respect to conventional bell nozzles. The nozzle wall-pressure signature is analyzed in the frequency domain and compared with the experimental data available in the literature for the same geometry and flow conditions. The Fourier spectra in time and space (azimuthal wavenumber) show the presence of a persistent tone associated to the symmetric shock movement. Asymmetric modes are only slightly excited by the shock and the turbulent structures. The low mean value of the side-loads magnitude is in good agreement with the experiments and confirms that the inflection point dampens the aero-acoustic interaction between the separation-shock and the detached shear layer.
26
Du, Shouhong, Larry S. Fung, and Ali H. Dogru. "Aquifer Acceleration in Parallel Implicit Field-Scale Reservoir Simulation." SPE Journal 23, no. 02 (February 12, 2018): 614–24. http://dx.doi.org/10.2118/182686-pa.
Анотація:
Summary Grid coarsening outside of the areas of interest is a common method to reduce computational cost in reservoir simulation. Aquifer regions are candidates for grid coarsening. In this situation, upscaling is applied to the fine grid to generate coarse-grid flow properties. The efficacy of the approach can be judged easily by comparing the simulation results between the coarse-grid model and the fine-grid model. For many reservoirs in the Middle East bordered by active aquifers, transient water influx is an important recovery mechanism that needs to be modeled correctly. Our experience has shown that the standard grid coarsening and upscaling method do not produce correct results in this situation. Therefore, the objective of this work is to build a method that retains the fine-scale heterogeneities to accurately represent the water movement, but to significantly reduce the computational cost of the aquifer grids in the model. The new method can be viewed as a modified two-level multigrid (MTL-MG) or a specialized adaptation of the multiscale method. It makes use of the vertical-equilibrium (VE) concept in the fine-scale pressure reconstruction in which it is applicable. The method differs from the standard grid coarsening and upscaling method in which the coarse-grid properties are computed a priori. Instead, the fine-scale information is restricted to the coarse grid during Newton's iteration to represent the fine-scale flow behavior. Within the aquifer regions, each column of fine cells is coarsened vertically based on fine-scale z-transmissibility. A coarsened column may consist of a single amalgamated aquifer cell or multiple vertically disconnected aquifer cells separated by flow barriers. The pore volume (PV), compressibility, and lateral flow terms of the coarse cell are restricted from the fine-grid cells. The lateral connectivity within the aquifer regions and the one between the aquifer and the reservoir are honored, inclusive of the fine-scale description of faults, pinchouts, and null cells. Reservoir regions are not coarsened. Two alternatives exist for the fine-scale pressure reconstruction from the coarse-grid solution. The first method uses the VE concept. When VE applies, pressure variation can be analytically computed in the solution update step. Otherwise, the second method is to apply a 1D z-line solve for the fine-scale aquifer pressure from the coarse-grid solution. Simulation results for several examples are included to demonstrate the efficacy and efficiency of the method. We have applied the method to several Saudi Arabian complex full-field simulation models in which the transient aquifer water influx has been identified as a key factor. These models include dual-porosity/dual-permeability (DPDP) models, as well as models with faults and pinchouts in corner-point-geometry grids, for both history match and prediction period. The method is flexible and allows for the optional selection of aquifer regions to be coarsened, either only peripheral aquifers or both the peripheral and bottom aquifers. The new method gives nearly identical results compared with the original runs without coarsening, but with significant reduction in computer time or hardware cost. These results will be detailed in the paper.
27
Haji, Hind, Abdelghani Saouab, and Chung Hae Park. "Particles Deposit Formation and Filtering: Numerical Simulation in the Suspension Flow Through a Dual Scale Fibrous Media." Macromolecular Symposia 340, no. 1 (June 2014): 44–51. http://dx.doi.org/10.1002/masy.201300121.
28
Geiger, S., M. Dentz, and I. Neuweiler. "A Novel Multirate Dual-Porosity Model for Improved Simulation of Fractured and Multiporosity Reservoirs." SPE Journal 18, no. 04 (May 27, 2013): 670–84. http://dx.doi.org/10.2118/148130-pa.
Анотація:
Summary A major part of the world's remaining oil reserves is in fractured carbonate reservoirs, which are dual-porosity (fracture-matrix) or multiporosity (fracture/vug/matrix) in nature. Fractured reservoirs suffer from poor recovery, high water cut, and generally low performance. They are modeled commonly by use of a dual-porosity approach, which assumes that the high-permeability fractures are mobile and low-permeability matrix is immobile. A single transfer function models the rate at which hydrocarbons migrate from the matrix into the fractures. As shown in many numerical, laboratory, and field experiments, a wide range of transfer rates occurs between the immobile matrix and mobile fractures. These arise, for example, from the different sizes of matrix blocks (yielding a distribution of shape factors), different porosity types, or the inhomogeneous distribution of saturations in the matrix blocks. Thus, accurate models are needed that capture all the transfer rates between immobile matrix and mobile fracture domains, particularly to predict late-time recovery more reliably when the water cut is already high. In this work, we propose a novel multi-rate mass-transfer (MRMT) model for two-phase flow, which accounts for viscous-dominated flow in the fracture domain and capillary flow in the matrix domain. It extends the classical (i.e., single-rate) dual-porosity model to allow us to simulate the wide range of transfer rates occurring in naturally fractured multiporosity rocks. We demonstrate, by use of numerical simulations of waterflooding in naturally fractured rock masses at the gridblock scale, that our MRMT model matches the observed recovery curves more accurately compared with the classical dual-porosity model. We further discuss how our multi-rate dual-porosity model can be parameterized in a predictive manner and how the model could be used to complement traditional commercial reservoir-simulation workflows.
29
Gong, Bin, Mohammad Karimi-Fard, and Louis J. Durlofsky. "Upscaling Discrete Fracture Characterizations to Dual-Porosity, Dual-Permeability Models for Efficient Simulation of Flow With Strong Gravitational Effects." SPE Journal 13, no. 01 (March 1, 2008): 58–67. http://dx.doi.org/10.2118/102491-pa.
Анотація:
Summary The geological complexity of fractured reservoirs requires the use of simplified models for flow simulation. This is often addressed in practice by using flow modeling procedures based on the dual-porosity, dual-permeability concept. However, in most existing approaches, there is not a systematic and quantitative link between the underlying geological model [in this case, a discrete fracture model (DFM)] and the parameters appearing in the flow model. In this work, a systematic upscaling procedure is presented to construct a dual-porosity, dual-permeability model from detailed discrete fracture characterizations. The technique, referred to as a multiple subregion (MSR) model, represents an extension of an earlier method that did not account for gravitational effects. The subregions (or subgrid) are constructed for each coarse block using the iso-pressure curves obtained from local pressure solutions of a discrete fracture model over the block. The subregions thus account for the fracture distribution and can represent accurately the matrix-matrix and matrix-fracture transfer. The matrix subregions are connected to matrices in vertically adjacent blocks (as in a dual-permeability model) to capture phase segregation caused by gravity. Two-block problems are solved to provide fracture-fracture flow effects. All connections in the coarse-scale model are characterized in terms of upscaled transmissibilities, and the resulting coarse model can be used with any connectivity-based reservoir simulator. The method is applied to simulate 2D and 3D fracture models, with viscous, gravitational, and capillary pressure effects, and is shown to provide results in close agreement with the underlying DFM. Speedups of approximately a factor of 120 are observed for a complex 3D example. Introduction The accurate simulation of fractured reservoirs remains a significant challenge. Although improvements in many technical areas are required to enable reliable predictions, there is a clear need for procedures that provide accurate and efficient flow models from highly resolved geological characterizations. These geological descriptions are often in the form of discrete fracture representations, which are generally too detailed for direct use in reservoir simulation. Dual-porosity modeling is the standard simulation technique for flow prediction of fractured reservoirs. This model was first proposed by Barenblatt and Zheltov (1960) and introduced to the petroleum industry by Warren and Root (1963). The key aspect of this approach is to separate the flow through the fractures from the flow inside the matrix. The reservoir model is represented by two overlapping continua—one continuum to represent the fracture network, where the main flow occurs, and another continuum to represent the matrix, which acts as a source for the fracture continuum. The interaction between these two continua is modeled through a transfer function, also called the shape factor. Though very useful, the model is quite simple in that the geological and flow complexity is reduced to a single parameter, the shape factor. This parameter is in general different for each gridblock depending on the underlying geology and the type of flow.
30
Wei, Xiao Wei. "The Analysis of Traffic Flow Model." Applied Mechanics and Materials 380-384 (August 2013): 237–40. http://dx.doi.org/10.4028/www.scientific.net/amm.380-384.237.
Анотація:
With worsening traffic condition in large and medium-sized cities, it has become one of the most important steps for the urban traffic strategy to solve the traffic problems. Since the urban traffic is a complex system in various factors and huge scale, to establish related mathematical model through computer numerical simulation is a significant solution to the comprehensive problems of complex analysis, decision and planning. At present researches on the problems have been achieved in many foreign countries, but domestic research is not enough, especially in the practical application. The macroscopic traffic flow model and microscopic traffic flow model are described and cellular automaton model, dual channel decision model and car-following model are analyzed in this paper, prediction of the ideal traffic flow and trip distribution is consequently concluded, which deepen the understanding to the traffic flow of various phenomenon intrinsic mechanism and predict most closely to the actual situation of traffic flow, which can make fundamental work for traffic flow simulation and for real-time traffic control[1-3].
31
Di Donato, Ginevra, Huiyun Lu, Zohreh Tavassoli, and Martin Julian Blunt. "Multirate-Transfer Dual-Porosity Modeling of Gravity Drainage and Imbibition." SPE Journal 12, no. 01 (March 1, 2007): 77–88. http://dx.doi.org/10.2118/93144-pa.
Анотація:
Summary We develop a physically motivated approach to modeling displacement processes in fractured reservoirs. To find matrix/fracture transfer functions in a dual-porosity model, we use analytical expressions for the average recovery as a function of time for gas gravity drainage and countercurrent imbibition. For capillary-controlled displacement, the recovery tends to its ultimate value with an approximately exponential decay (Barenblatt et al. 1990). When gravity dominates, the approach to ultimate recovery is slower and varies as a power law with time (Hagoort 1980). We apply transfer functions based on these expressions for core-scale recovery in field-scale simulation. To account for heterogeneity in wettability, matrix permeability, and fracture geometry within a single gridblock, we propose a multirate model (Ponting 2004). We allow the matrix to be composed of a series of separate domains in communication with different fracture sets with different rate constants in the transfer function. We use this methodology to simulate recovery in a Chinese oil field to assess the efficiency of different injection processes. We use a streamline-based formulation that elegantly allows the transfer between fracture and matrix to be accommodated as source terms in the 1D transport equations along streamlines that capture the flow in the fractures (Di Donato et al. 2003; Di Donato and Blunt 2004; Huang et al. 2004). This approach contrasts with the current Darcy-like formulation for fracture/matrix transfer based on a shape factor (Gilman and Kazemi 1983) that may not give the correct average behavior (Di Donato et al. 2003; Di Donato and Blunt 2004; Huang et al. 2004). Furthermore, we show that recovery is exceptionally sensitive to parameters that describe the physics of the displacement process, highlighting the need to make careful core-scale measurements of recovery. Introduction Di Donato et al.(2003) and Di Donato and Blunt (2004) proposed a dual-porosity streamline-based model for simulating flow in fractured reservoirs. Conceptually, the reservoir is composed of two domains: a flowing region with high permeability that represents the fracture network and a stagnant region with low permeability that represents the matrix (Barenblatt et al. 1960; Warren and Root 1963). The streamlines capture flow in the flowing regions, while transfer from fracture to matrix is accommodated as source/sink terms in the transport equations along streamlines. Di Donato et al. (2003) applied this methodology to study capillary-controlled transfer between fracture and matrix and demonstrated that using streamlines allowed multimillion-cell models to be run using standard computing resources. They showed that the run time could be orders of magnitude smaller than equivalent conventional grid-based simulation (Huang et al. 2004). This streamline approach has been applied by other authors (Al-Huthali and Datta-Gupta 2004) who have extended the method to include gravitational effects, gas displacement, and dual-permeability simulation, where there is also flow in the matrix. Thiele et al. (2004) have described a commercial implementation of a streamline dual-porosity model based on the work of Di Donato et al. that efficiently solves the 1D transport equations along streamlines.
32
Zhou, Hui, and Hamdi A. Tchelepi. "Operator-Based Multiscale Method for Compressible Flow." SPE Journal 13, no. 02 (June 1, 2008): 267–73. http://dx.doi.org/10.2118/106254-pa.
Анотація:
Summary Multiscale methods have been developed for accurate and efficient numerical solution of flow problems in large-scale heterogeneous reservoirs. A scalable and extendible Operator-Based Multiscale Method (OBMM) is described here. OBMM is cast as a general algebraic framework. It is natural and convenient to incorporate more physics in OBMM for multiscale computation. In OBMM, two operators are constructed: prolongation and restriction. The prolongation operator is constructed by assembling the multiscale basis functions. The specific form of the restriction operator depends on the coarse-scale discretization formulation (e.g., finitevolume or finite-element). The coarse-scale pressure equation is obtained algebraically by applying the prolongation and restriction operators to the fine-scale flow equations. Solving the coarse-scale equation results in a high-quality coarse-scale pressure. The finescale pressure can be reconstructed by applying the prolongation operator to the coarse-scale pressure. A conservative fine-scale velocity field is then reconstructed to solve the transport (saturation) equation. We describe the OBMM approach for multiscale modeling of compressible multiphase flow. We show that extension from incompressible to compressible flows is straightforward. No special treatment for compressibility is required. The efficiency of multiscale formulations over standard fine-scale methods is retained by OBMM. The accuracy of OBMM is demonstrated using several numerical examples including a challenging depletion problem in a strongly heterogeneous permeability field (SPE 10). Introduction The accuracy of simulating subsurface flow relies strongly on the detailed geologic description of the porous formation. Formation properties such as porosity and permeability typically vary over many scales. As a result, it is not unusual for a detailed geologic description to require 107-108 grid cells. However, this level of resolution is far beyond the computational capability of state-of-the-art reservoir simulators (106 grid cells). Moreover, in many applications, large numbers of reservoir simulations are performed (e.g., history matching, sensitivity analysis and stochastic simulation). Thus, it is necessary to have an efficient and accurate computational method to study these highly detailed models. Multiscale formulations are very promising due to their ability to resolve fine-scale information accurately without direct solution of the global fine-scale equations. Recently, there has been increasing interest in multiscale methods. Hou and Wu (1997) proposed a multiscale finite-element method (MsFEM) that captures the fine-scale information by constructing special basis functions within each element. However, the reconstructed fine-scale velocity is not conservative. Later, Chen and Hou (2003) proposed a conservative mixed finite-element multiscale method. Another multiscale mixed finite element method was presented by Arbogast (2002) and Arbogast and Bryant (2002). Numerical Green functions were used to resolve the fine-scale information, which are then coupled with coarse-scale operators to obtain the global solution. Aarnes (2004) proposed a modified mixed finite-element method, which constructs special basis functions sensitive to the nature of the elliptic problem. Chen et al. (2003) developed a local-global upscaling method by extracting local boundary conditions from a global solution, and then constructing coarse-scale system from local solutions. All these methods considered incompressible flow in heterogeneous porous media where the pressure equation is elliptic. A multiscale finite-volume method (MsFVM) was proposed by Jenny et al. (2003, 2004, 2006) for heterogeneous elliptic problems. They employed two sets of basis functions--dual and primal. The dual basis functions are identical to those of Hou and Wu (1997), while the primal basis functions are obtained by solving local elliptic problems with Neumann boundary conditions calculated from the dual basis functions. Existing multiscale methods (Aarnes 2004; Arbogast 2002; Chen and Hou 2003; Hou and Wu 1997; Jenny et al. 2003) deal with the incompressible flow problem only. However, compressibility will be significant if a gas phase is present. Gas has a large compressibility, which is a strong function of pressure. Therefore, there can be significant spatial compressibility variations in the reservoir, and this is a challenge for multiscale modeling. Very recently, Lunati and Jenny (2006) considered compressible multiphase flow in the framework of MsFVM. They proposed three models to account for the effects of compressibility. Using those models, compressibility effects were represented in the coarse-scale equations and the reconstructed fine-scale fluxes according to the magnitude of compressibility. Motivated to construct a flexible algebraic multiscale framework that can deal with compressible multiphase flow in highly detailed heterogeneous models, we developed an operator-based multiscale method (OBMM). The OBMM algorithm is composed of four steps:constructing the prolongation and restriction operators,assembling and solving the coarse-scale pressure equations,reconstructing the fine-scale pressure and velocity fields, andsolving the fine-scale transport equations. OBMM is a general algebraic multiscale framework for compressible multiphase flow. This algebraic framework can also be extended naturally from structured to unstructured grid. Moreover, the OBMM approach may be used to employ multiscale solution strategies in existing simulators with a relatively small investment.
33
Fracassi, Fabiano T., and Maurício V. Donadon. "Simulation of vacuum assisted resin transfer molding process through dynamic system analysis." Journal of Composite Materials 52, no. 27 (April 13, 2018): 3759–71. http://dx.doi.org/10.1177/0021998318770000.
Анотація:
Vacuum assisted resin transfer molding is a promising process in advanced composite manufacturing with a wide range of applications in industry. That potential is often misused, though, because of the lack of an efficient and reliable simulation tool to support product development. Most of the simulation methods in use today are based on Darcy’s law, which explains the permeation of a fluid in a porous medium. However, it is known that this law has limitations when applied to the context of dual-scale fibrous reinforcements: macro porosity given by fiber architecture generates resistance to flow, while the inner porosity inherent to fiber tows causes it to absorb resin, affecting the flow. The latter effect cannot be explained by traditional theory. In order to explore these limitations, this work proposes a simplified model to vacuum assisted resin transfer molding process from the point of view of system dynamics, and to prove the viability of such theory. The ultimate goal is to propose a more complete model in light of system dynamics that saves time and cost while offering the same reliability as current simulation models. In order to provide an explanation to both dual-scale phenomena, a parallel association between a resistance and a fluid capacitance is proposed. Model validation is then performed through the analysis of experimental data followed by the comparison between the Darcy infusion profile and the one predicted by the resistor-capacitor-parallel (RC-parallel) circuit model. Thus, this work is able to perform a proof of concept that leads to a novel and yet unexplored field of study.
34
Su, Bei, Ying-Guo Zhou, and Lih-Sheng Turng. "Dual-Scale Modeling and Simulation of Skin Layer Thickness in Injection Molding with Variable Mold Temperatures." Journal of Computational and Theoretical Nanoscience 13, no. 10 (October 1, 2016): 7125–36. http://dx.doi.org/10.1166/jctn.2016.5681.
Анотація:
Compared with the constant mold temperature in conventional injection molding (CIM), injection molded parts with variable mold temperatures undergo a different thermomechanical history. As a result, the microstructure—for example, the skin–core structure found often in CIM—can be changed. However, unlike conventional injection molding, there have been few studies on the microstructure of injection molding with variable mold temperatures (IMVMT), possibly because the experimental control of variable mold temperatures remains difficult. In this paper, the skin layer thickness of CIM and IMVMT under different mold temperatures was carefully investigated by optical microscope. The higher mold temperatures and longer holding times during the injection flow stage caused a thinning of the highly oriented skin layer, and vice-versa. A dual-scale modeling was then proposed based on the prediction of crystal dimensions, and it was further used to predict the thickness of the skin layer. The predicted results were in agreement with the experimental observations under the different mold temperatures during IMVMT processing, and the proposed model proved to be effective.
35
Gómez, Manuel, Joan Recasens, Beniamino Russo, and Eduardo Martínez-Gomariz. "Assessment of inlet efficiency through a 3D simulation: numerical and experimental comparison." Water Science and Technology 74, no. 8 (August 9, 2016): 1926–35. http://dx.doi.org/10.2166/wst.2016.326.
Анотація:
Inlet efficiency is a requirement for characterizing the flow transfers between surface and sewer flow during rain events. The dual drainage approach is based on the joint analysis of both upper and lower drainage levels, and the flow transfer is one of the relevant elements to define properly this joint behaviour. This paper presents the results of an experimental and numerical investigation about the inlet efficiency definition. A full scale (1:1) test platform located in the Technical University of Catalonia (UPC) reproduces both the runoff process in streets and the water entering the inlet. Data from tests performed on this platform allow the inlet efficiency to be estimated as a function of significant hydraulic and geometrical parameters. A reproduction of these tests through a numerical three-dimensional code (Flow-3D) has been carried out simulating this type of flow by solving the RANS equations. The aim of the work was to reproduce the hydraulic performance of a previously tested grated inlet under several flow and geometric conditions using Flow-3D as a virtual laboratory. This will allow inlet efficiencies to be obtained without previous experimental tests. Moreover, the 3D model allows a better understanding of the hydraulics of the flow interception and the flow patterns approaching the inlet.
36
Sarda, S., L. Jeannin, R. Basquet, and B. Bourbiaux. "Hydraulic Characterization of Fractured Reservoirs: Simulation on Discrete Fracture Models." SPE Reservoir Evaluation & Engineering 5, no. 02 (April 1, 2002): 154–62. http://dx.doi.org/10.2118/77300-pa.
Анотація:
Summary Advanced characterization methodology and software are now able to provide realistic pictures of fracture networks. However, these pictures must be validated against dynamic data like flowmeter, well-test, interference-test, or production data and calibrated in terms of hydraulic properties. This calibration and validation step is based on the simulation of those dynamic tests. What has to be overcome is the challenge of both accurately representing large and complex fracture networks and simulating matrix/ fracture exchanges with a minimum number of gridblocks. This paper presents an efficient, patented solution to tackle this problem. First, a method derived from the well-known dual-porosity concept is presented. The approach consists of developing an optimized, explicit representation of the fractured medium and specific treatments of matrix/fracture exchanges and matrix/matrix flows. In this approach, matrix blocks of different volumes and shapes are associated with each fracture cell depending on the local geometry of the surrounding fractures. The matrix-block geometry is determined with a rapid image-processing algorithm. The great advantage of this approach is that it can simulate local matrix/fracture exchanges on large fractured media in a much faster and more appropriate way. Indeed, the simulation can be carried out with a much smaller number of cells compared to a fully explicit discretization of both matrix and fracture media. The proposed approach presents other advantages owing to its great flexibility. Indeed, it accurately handles the cases in which flows are not controlled by fractures alone; either the fracture network may be not hydraulically connected from one well to another, or the matrix may have a high permeability in some places. Finally, well-test cases demonstrate the reliability of the method and its range of application. Introduction In recent years, numerous research programs have been focusing on the topic of fractured reservoirs. Major advances were made, and oil companies now benefit from efficient methodologies, tools, and software for fractured reservoir studies. Nowadays, a study of a fractured reservoir, from fracture detection to full-field simulation, includes the following main steps: geological fracture characterization, hydraulic characterization of fractures, upscaling of fracture properties, and fractured reservoir simulation. Research on fractured reservoir simulation has a long history. In the early 1960s, Barenblatt and Zheltov1 first introduced the dual-porosity concept, followed by Warren and Root,2 who proposed a simplified representation of fracture networks to be used in dual-porosity simulators. Based on this concept, reservoir simulators3 are now able to correctly reproduce the main driving mechanisms occurring in fractured reservoirs, such as water imbibition, gas/oil and water/oil gravity drainage, molecular diffusion, and convection in fractures. Even single-medium simulators can perform fractured reservoir simulation when adequate pseudocapillary pressure curves and pseudorelative permeability curves can be input. Indeed, except for particular cases such as thermal recovery processes, full-field simulation of fractured reservoirs is no longer a problem. Geological characterization of fractures progressed considerably in the 1990s. The challenge was to analyze and integrate all the available fracture data to provide a reliable description of the fracture network both at field scale and at local reservoir cell scale. Tools have been developed for merging seismic, borehole imaging, lithological, and outcrop data together with the help of geological and geomechanical rules.3 These tools benefited from the progress of seismic acquisition and borehole imaging. Indeed, accurate seismic data lead to reliable models of large-scale fracture networks, and borehole imaging gives the actual fracture description along the wells, which enables a reliable statistical determination of fracture attributes. Finally, these tools provide realistic pictures of fracture networks. They are applied successfully in numerous fractured-reservoir studies. The upscaling of fracture properties is the problem of translating the geological description of fracture networks into reservoir simulation parameters. Two approaches are possible. In the first one, the fractured reservoir is considered as a very heterogeneous matrix reservoir; therefore, one applies the classical techniques available for heterogeneous single-medium upscaling. The second approach is based on the dual-porosity concept and consists of upscaling the matrix and the fracture separately. Based on this second approach, methodologies and software were developed in the 1990s to calculate equivalent fracture parameters with respect to the dual-porosity concept (i.e., a fracture-permeability tensor with main flow directions and anisotropy and a shape factor that controls the matrix/fracture exchange kinetics3–5). For a given reservoir grid cell, the upscaling procedures consist of generating the corresponding 3D discrete fracture network and computing the equivalent parameters from this network. In particular, the permeability tensor is computed from the results of steady-state flow simulations in the discrete fracture network alone (without the matrix).
37
Besien, T. J., N. J. Jarvis, and R. J. Williams. "Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model." Hydrology and Earth System Sciences 1, no. 4 (December 31, 1997): 835–44. http://dx.doi.org/10.5194/hess-1-835-1997.
Анотація:
Abstract. In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications) could potentially reduce pesticide leaching to surface waters by up to 60%.
38
Pillai, Krishna M., and Murthy S. Munagavalasa. "A Deviation from Darcy's Law due to Unsaturated Flow in Dual-Scale Porous Media." Journal of Porous Media 12, no. 4 (2009): 327–44. http://dx.doi.org/10.1615/jpormedia.v12.i4.40.
39
YEH, LI-MING. "HOMOGENIZATION OF TWO-PHASE FLOW IN FRACTURED MEDIA." Mathematical Models and Methods in Applied Sciences 16, no. 10 (October 2006): 1627–51. http://dx.doi.org/10.1142/s0218202506001650.
Анотація:
In a fractured medium, there is an interconnected system of fracture planes dividing the porous rock into a collection of matrix blocks. The fracture planes, while very thin, form paths of high permeability. Most of the fluids reside in matrix blocks, where they move very slow. Let ε denote the size ratio of the matrix blocks to the whole medium and let the width of the fracture planes and the porous block diameter be in the same order. If permeability ratio of matrix blocks to fracture planes is of order ε2, microscopic models for two-phase, incompressible, immiscible flow in fractured media converge to a dual-porosity model as ε goes to 0. If the ratio is smaller than order ε2, the microscopic models approach a single-porosity model for fracture flow. If the ratio is greater than order ε2, then microscopic models tend to another type of single-porosity model. In this work, these results will be proved by a two-scale method.
40
Li, Chen, Qi-Long Guo, Dong Sun, and Han-Xin Zhang. "Aerothermal prediction of hypersonic flow around spherical capsule model using IDDES approach." International Journal of Modern Physics B 34, no. 14n16 (May 30, 2020): 2040078. http://dx.doi.org/10.1142/s0217979220400780.
Анотація:
The prediction of heat transfer for blunt bodies in hypersonic flows remains a great challenge. In particular, the uncertainties are larger in the leeside due to the complexity of the wake flow. Generally, the heat transfer is over-predicted using the Reynolds-averaged Navier–Stokes (RANS) models. In this paper, the improved delayed detached eddy simulation (IDDES) method is used to simulate the Mach 6 flow around a scaled spherical capsule model. In addition, a low dissipative WENO scheme is used for inviscid fluxes and dual-time stepping method is applied for time advancement. Results are compared to experimental data for mean and instantaneous heat transfer in the leeside of the aftbody. It is shown that the integrated error is 75.49% for RANS while 35.69% for IDDES method. Moreover, the multi-scale structures in the separation region are also resolved well by the IDDES method.
41
Zheng, Zhong, Liangcheng Lin, Zhiwei Chen, Jim Lim, and John Grace. "A dual-scale lattice gas automata model for gas–solid two-phase flow in bubbling fluidized beds." Computers & Mathematics with Applications 61, no. 12 (June 2011): 3593–605. http://dx.doi.org/10.1016/j.camwa.2011.01.030.
42
AMAZIANE, B., L. PANKRATOV, and A. PIATNITSKI. "HOMOGENIZATION OF A SINGLE PHASE FLOW THROUGH A POROUS MEDIUM IN A THIN LAYER." Mathematical Models and Methods in Applied Sciences 17, no. 09 (September 2007): 1317–49. http://dx.doi.org/10.1142/s0218202507002339.
Анотація:
The paper deals with homogenization of stationary and non-stationary high contrast periodic double porosity type problem stated in a porous medium containing a 2D or 3D thin layer. We consider two different types of high contrast medium. The medium of the first type is characterized by the asymptotically vanishing volume fraction of fractures (highly permeable part). The medium of the second type has uniformly positive volume fraction of fracture part. In both cases we construct the homogenized models and prove the convergence results. The techniques used in this work are based on a special version of the two-scale convergence method adapted to thin structures. The resulting homogenized problems are dual-porosity type models that contain terms representing memory effects.
43
Du, Kai, Jingni Song, Weiyu Liu, Ye Tao, and Yukun Ren. "Multifrequency Induced-Charge Electroosmosis." Micromachines 10, no. 7 (July 3, 2019): 447. http://dx.doi.org/10.3390/mi10070447.
Анотація:
We present herein a unique concept of multifrequency induced-charge electroosmosis (MICEO) actuated directly on driving electrode arrays, for highly-efficient simultaneous transport and convective mixing of fluidic samples in microscale ducts. MICEO delicately combines transversal AC electroosmotic vortex flow, and axial traveling-wave electroosmotic pump motion under external dual-Fourier-mode AC electric fields. The synthetic flow field associated with MICEO is mathematically analyzed under thin layer limit, and the particle tracing experiment with a special powering technique validates the effectiveness of this physical phenomenon. Meanwhile, the simulation results with a full-scale 3D computation model demonstrate its robust dual-functionality in inducing fully-automated analyte transport and chaotic stirring in a straight fluidic channel embedding double-sided quarter-phase discrete electrode arrays. Our physical demonstration with multifrequency signal control on nonlinear electroosmosis provides invaluable references for innovative designs of multifunctional on-chip analytical platforms in modern microfluidic systems.
44
Jonoud, S., O. P. P. Wennberg, G. Casini, and J. A. A. Larsen. "Capturing the Effect of Fracture Heterogeneity on Multiphase Flow During Fluid Injection." SPE Reservoir Evaluation & Engineering 16, no. 02 (May 8, 2013): 194–208. http://dx.doi.org/10.2118/147834-pa.
Анотація:
Summary Carbonate fractured reservoirs introduce a tremendous challenge to the upscaling of both single- and multiphase flow. The complexity comes from both heterogeneous matrix and fracture systems in which the separation of scales is very difficult. The mathematical upscaling techniques, derived from representative elementary volume (REV), must therefore be replaced by a more realistic geology-based approach. In the case of multiphase flow, an evaluation of the main forces acting during oil recovery must also be performed. A matrix-sector model from a highly heterogeneous carbonate reservoir is linked to different fracture realizations in dual-continuum simulations. An integrated iterative workflow between the geology-based static modeling and the dynamic simulations is used to investigate the effect of fracture heterogeneity on multiphase fluid flow. Heterogeneities at various scales (i.e., diffuse fractures and subseismic faults) are considered. The diffuse-fracture model is built on the basis of facies and porosity from the matrix model together with core data, image-log data, and data from outcrop-analogs. Because of poor seismic data, the subseismic-fault model is mainly conceptual and is based on the analysis of outcrop-analog data. Fluid-flow simulations are run for both single-phase and multiphase flow and gas and water injections. A better understanding of fractured-reservoirs behavior is achieved by incorporating realistic fracture heterogeneity into the geological model and analyzing the dynamic impact of fractures at various scales. In the case of diffuse fractures, the heterogeneity effect can be captured in the upscaled model. The subseismic faults, however, must be explicitly represented, unless the sigma (shape) factor is included in the upscaling process. A local grid-refinement approach is applied to demonstrate explicit fractures in large-scale simulation grids. This study provides guidelines on how to effectively scale up a heterogeneous fracture model and still capture the heterogeneous flow behavior.
45
Pantaloni, Delphin, Alain Bourmaud, Christophe Baley, Mike J. Clifford, Michael H. Ramage, and Darshil U. Shah. "A Review of Permeability and Flow Simulation for Liquid Composite Moulding of Plant Fibre Composites." Materials 13, no. 21 (October 28, 2020): 4811. http://dx.doi.org/10.3390/ma13214811.
Анотація:
Liquid composite moulding (LCM) of plant fibre composites has gained much attention for the development of structural biobased composites. To produce quality composites, better understanding of the resin impregnation process and flow behaviour in plant fibre reinforcements is vital. By reviewing the literature, we aim to identify key plant fibre reinforcement-specific factors that influence, if not govern, the mould filling stage during LCM of plant fibre composites. In particular, the differences in structure (physical and biochemical) for plant and synthetic fibres, their semi-products (i.e., yarns and rovings), and their mats and textiles are shown to have a perceptible effect on their compaction, in-plane permeability, and processing via LCM. In addition to examining the effects of dual-scale flow, resin absorption, (subsequent) fibre swelling, capillarity, and time-dependent saturated and unsaturated permeability that are specific to plant fibre reinforcements, we also review the various models utilised to predict and simulate resin impregnation during LCM of plant fibre composites.
46
Potvin, Corey K., Louis J. Wicker, and Alan Shapiro. "Assessing Errors in Variational Dual-Doppler Wind Syntheses of Supercell Thunderstorms Observed by Storm-Scale Mobile Radars." Journal of Atmospheric and Oceanic Technology 29, no. 8 (August 1, 2012): 1009–25. http://dx.doi.org/10.1175/jtech-d-11-00177.1.
Анотація:
Abstract Dual-Doppler wind retrieval is an invaluable tool in the study of convective storms. However, the nature of the errors in the retrieved three-dimensional wind estimates and subsequent dynamical analyses is not precisely known, making it difficult to assign confidence to inferred storm behavior. Using an Observing System Simulation Experiment (OSSE) framework, this study characterizes these errors for a supercell thunderstorm observed at close range by two Doppler radars. Synthetic radar observations generated from a high-resolution numerical supercell simulation are input to a three-dimensional variational data assimilation (3DVAR) dual-Doppler wind retrieval technique. The sensitivity of the analyzed kinematics and dynamics to the dual-Doppler retrieval settings, hydrometeor fall speed parameterization errors, and radar cross-beam angle and scanning strategy is examined. Imposing the commonly adopted assumptions of spatially constant storm motion and intrinsically steady flow produces large errors at higher altitudes. On the other hand, reasonably accurate analyses are obtained at lower and middle levels, even when the majority of the storm lies outside the 30° dual-Doppler lobe. Low-level parcel trajectories initiated around the main updraft and rear-flank downdraft are generally qualitatively accurate, as are time series of circulation computed around material circuits. Omitting upper-level radar observations to reduce volume scan times does not substantially degrade the lower- and middle-level analyses, which implies that shallower scanning strategies should enable an improved retrieval of supercell dynamics. The results suggest that inferences about supercell behavior based on qualitative features in 3DVAR dual-Doppler and subsequent dynamical retrievals may generally be reliable.
47
Jackisch, Conrad, and Erwin Zehe. "Ecohydrological particle model based on representative domains." Hydrology and Earth System Sciences 22, no. 7 (July 6, 2018): 3639–62. http://dx.doi.org/10.5194/hess-22-3639-2018.
Анотація:
Abstract. Non-uniform infiltration and subsurface flow in structured soils is observed in most natural settings. It arises from imperfect lateral mixing of fast advective flow in structures and diffusive flow in the soil matrix and remains one of the most challenging topics with respect to match observation and modelling of water and solutes at the plot scale. This study extends the fundamental introduction of a space domain random walk of water particles as an alternative approach to the Richards equation for diffusive flow (Zehe and Jackisch, 2016) to a stochastic–physical model framework simulating soil water flow in a representative, structured soil domain. The central objective of the proposed model is the simulation of non-uniform flow fingerprints in different ecohydrological settings and antecedent states by making maximum use of field observables for parameterisation. Avoiding non-observable parameters for macropore–matrix exchange, an energy-balance approach to govern film flow in representative flow paths is employed. We present the echoRD model (ecohydrological particle model based on representative domains) and a series of application test cases. The model proves to be a powerful alternative to existing dual-domain models, driven by experimental data and with self-controlled, dynamic macropore–matrix exchange from the topologically semi-explicitly defined structures.
48
Stone, T. W., J. Bennett, D. H. S. Law, and J. A. Holmes. "Thermal Simulation With Multisegment Wells." SPE Reservoir Evaluation & Engineering 5, no. 03 (June 1, 2002): 206–18. http://dx.doi.org/10.2118/78131-pa.
Анотація:
Summary The extension of a previously reported well model to compositional and thermal applications is discussed. This multisegment, multibranching wellbore model has been fully coupled to a commercial reservoir simulator that can operate in black-oil, compositional, or thermal modes. In this paper, the discussion will focus on thermal, heavy-oil applications in which simulation requires a better representation of the wellbore geometry and the physics of fluid flow and heat transfer. Introduction Gravity-drainage processes with possible steam (SAGD) or gas vapor (VAPEX) assistance and other recovery technologies often require the use of long horizontal wells with flow in an inner tubing and outer annulus.1–3 Thermal studies that simulate horizontal wells have been discussed by many authors. Recovery techniques include cyclicsteam projects,4–10 dual-well SAGD,11 and single-well SAGD.12 In these studies, the oils are heavy (970 to 1014 kg/m3; 14 to 8°API), with viscosities ranging from 2,000 cp at 32°C in California fields up to 1,000,000 cp at 12°C for oils found at the UTF project13 in the Athabasca tar sands deposit. These studies have, for the most part, used the conventional wellbore line source/sink model available in any thermal simulator. Simulation technology for horizontal wells has improved dramatically since the late 1980s. At this time, Stone et al.14 described a horizontal well model that featured a mechanistic multiphase fluid-flow model in the wellbore and allowed flow simultaneously in an inner tubing and outer annulus. This was designed to handle simulations in the near-wellbore region of a dual-well SAGD process and, because of the more detailed flow regime map, could not handle larger-scale simulations for stability reasons. Also during this time period, Long et al.15 carried out the Seventh SPE Comparative Solution Project concerning the modeling of horizontal wells in reservoir simulation. A variety of methods was used by the participants to model the inflow into the horizontal well model. These included the use of an inflow performance relationship (IPR) with a separate well model or direct coupling by modeling the well as part of the grid. Similarly, there were various wellbore hydraulics models ranging from a constant-pressure line sink to friction pressure-drop relations or simple functional fits of published holdup correlations. All of these horizontal well models were designed to run robustly and stably in large-scale field simulations. However, some were limited in their ability to calculate a multiphase pressure drop, others in not allowing the wellbore model geometry to correspond to the engineering design of the well rather than to the simulation grid. Some methods allowed multiphase pressure drops with explicit updates or other approximations. Recently, Tan et al.16 have described a fully coupled discretized thermal wellbore model with the ability to simulate flow in casing/annulus wellbore cells. Estimates of the relative flow rates are made based on phase saturations and straight-line relative permeability curves. These estimates are passed to a subroutine that calculates flow rates from the correlated Beggs et al.17 measurements. Wellbore cells are connected to reservoir cells. A multisegment well model that can simulate flow in advanced wells was discussed by Holmes et al.18,19 This model, implemented in a commercial black-oil simulator, is able to determine the local flowing conditions (the flow rate and pressure of each fluid) throughout the well. It allows for pressure losses along the wellbore and across any flow-control devices. In addition to being fully implicitly coupled, with crossflow modeling and the standard group control facilities, horizontal wells, multilateral wells, and "smart" wells containing flow-control devices can also be modeled. The trajectory is not constrained by the simulation grid. For example, the wellbore may run outside the grid or across layers. Properties and geometry can be updated at any time in the simulation. In this paper, we first describe the implementation and enhancements to the implicit multisegment well model discussed in Ref. 18 that allow this model to run in compositional and thermal modes. In these modes, the equation of state (EOS) or thermal K-value treatment of the fluid pressure/volume/temperature (PVT) is extended to the wellbore flow. Phase volumes are computed in each segment and are then used to calculate the multiphase pressure drop. In thermal mode, an enhancement allows the definition of heat transfer coefficients, which permit heat loss to the reservoir, to another segment, or to the overburden. Another enhancement allows individual segments to inject or produce fluids, which permits the direct modeling of gas lift, downhole water pumps, or circulating wells, available in any mode. It is important in compositional, and especially thermal, wellbore simulations to provide an accurate initial estimate of the well solution; otherwise, there can be convergence problems. A method for predicting the initial state within the well is also shown later. We then present four case studies. Each case study has been set up from published engineering analyses of fields in western Canada and California, U.S.A. The well model used in these studies is considerably more detailed than that in the original published simulation work. Not only are the wellbore hydraulics more accurately modeled with multiphase flow models, but the geometry of the wells is also specified in more detail. Wellbore geometry includes the ability to run the well outside the simulation grid, allowing the modeling of heat loss from a steam-injection well to the formation, between the surface and the simulation grid. Also, an undulating well trajectory can be specified and is demonstrated in one of the studies. Fluid flow down an inner tubing and back along an outer completed annulus is demonstrated in three of the studies, in which heat transfer occurs between the inner tubing and the outer annulus and between the annulus and the formation. Two of these studies contain a segment at the heel of a horizontal annulus that removes fluids to an external sink, allowing part of the circulating fluids to return to the surface while the remainder are injected, produced, or stored in the wellbore. Where possible, differences are shown between the multisegment model and a standard line source/sink model that demonstrate the effects of modeling the improved wellbore physics. Description of the Multisegment Well Model The multisegment well model reported by Holmes et al.18 was originally implemented in a black-oil simulator. It uses four main variables: a total fluid-flow rate through the segment, weighted fractional flows of both water and gas, and pressure in the segment.
49
Carpenter, Chris. "Machine-Learning Upscales Realistic Discrete Fracture Simulations." Journal of Petroleum Technology 73, no. 11 (November 1, 2021): 65–66. http://dx.doi.org/10.2118/1121-0065-jpt.
Анотація:
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203962, “Upscaling of Realistic Discrete Fracture Simulations Using Machine Learning,” by Nikolai Andrianov, SPE, Geological Survey of Denmark and Greenland, prepared for the 2021 SPE Reservoir Simulation Conference, Galveston, Texas, 4–6 October. The paper has not been peer reviewed. Upscaling of discrete fracture networks to continuum models such as the dual-porosity/dual-permeability (DP/DP) model is an industry-standard approach in modeling fractured reservoirs. In the complete paper, the author parametrizes the fine-scale fracture geometries and assesses the accuracy of several convolutional neural networks (CNNs) to learn the mapping between this parametrization and DP/DP model closures. The accuracy of the DP/DP results with the predicted model closures was assessed by a comparison with the corresponding fine-scale discrete fracture matrix (DFM) simulation of a two-phase flow in a realistic fracture geometry. The DP/DP results matched the DFM reference solution well. The DP/DP model also was significantly faster than DFM simulation. Introduction The goal of this study was to evaluate the effect of different CNN architectures on prediction accuracy for the DP/DP model closures and on the accuracy of DP/DP simulations in comparison with fine-scale DFM simulations. As a starting point, two CNN configurations were considered that have achieved breakthrough performance in image-classification tasks. The author adopted these architectures to the problem of learning the mapping between pixelated fracture geometries and the DP/DP model closures and indicated several key features in the CNN structure that are crucial for achieving high prediction accuracy. Mapping of fracture geometries requires significant effort, which limits the possibilities for creating large training data sets with realistic fracture geometries. The author, therefore, used the synthetic random linear fractures’ data set to train the CNNs and the fracture geometry from the Lägerdorf outcrop for testing purposes. It was demonstrated that an optimal CNN configuration yielded the DP/DP model closures such that the corresponding DP/DP results matched well the two-phase DFM simulations on a subset of the Lägerdorf data. The run times for the DP/DP model were a fraction of the time needed to accomplish the DFM simulations. Problem formulation is presented in a series of equations in the complete paper.
50
Fontanarosa, Donato, Giacomo Cinieri, Maria Grazia De Giorgi, and Antonio Ficarella. "Effects of plasma kinetic modeling on performance characterization of plasma actuators for active flow control." E3S Web of Conferences 197 (2020): 10004. http://dx.doi.org/10.1051/e3sconf/202019710004.
Анотація:
This work focuses on the development of a multiscale computational fluid dynamics (CFD) simulation framework for the investigation of the effects of plasma kinetics on the performance of a microscale dielectric barrier discharge plasma actuator (DBD-PA). To this purpose, DBD-PA multi-scale dual-step modelling approach has been implemented, by considering plasma chemistry and flow dynamic. At first, a microscopic plasma model based on the air plasma kinetics has been defined and plasma reactions have been simulated in zero-dimensional computations in order to evaluate the charge density. At this aim computations have been performed using the toolbox ZDPlasKin, which solves plasma reactions by means of Bolsig+ solver. An alternate current (AC) electrical feeding has been assumed: in particular, the sinusoidal voltage amplitude and the frequency have been fixed at 5 kV and 1 kHz at atmospheric pressure and 300 K temperature in quiescent environment. The predictal charge density has been in a macroscopic plasma-fluid model based on Suzen Dual Potential Model (DPM), which has implemented in the computation fluid dynamic CFD code OpenFoam. Hence, as second step, 2D-CFD simulations of the electro-hydrodynamic body forces induced by the microscale DBDPA have been performed, based on the previously predicted charge densities at the operating conditions. Quiescent flow over a dielectric barrier discharge actuator has been simulated using the plasma-fluid model. The novel modelling framework has been validated with experimental data.