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Recent Submissions

  • The Effect of the Oleophobicity Deterioration of a Membrane Surface on Its Rejection Capacity: A Computational Fluid Dynamics Study

    Salama, Amgad; Alyan, Adel; El-Amin, Mohamed F.; Sun, Shuyu; Zhang, Tao; Zoubeik, Mohamed (Membranes, MDPI AG, 2021-03-31) [Article]
    In this work, the effects of the deteriorating affinity-related properties of membranes due to leaching and erosion on their rejection capacity were studied via computational fluid dynamics (CFD). The function of affinity-enhancing agents is to modify the wettability state of the surface of a membrane for dispersed droplets. The wettability conditions can be identified by the contact angle a droplet makes with the surface of the membrane upon pinning. For the filtration of fluid emulsions, it is generally required that the surface of the membrane is nonwetting for the dispersed droplets such that the interfaces that are formed at the pore openings provide the membrane with a criterion for the rejection of dispersals. Since materials that make up the membrane do not necessarily possess the required affinity, it is customary to change it by adding affinity-enhancing agents to the base material forming the membrane. The bonding and stability of these materials can be compromised during the lifespan of a membrane due to leaching and erosion (in crossflow filtration), leading to a deterioration of the rejection capacity of the membrane. In order to investigate how a decrease in the contact angle can lead to the permeation of droplets that would otherwise get rejected, a CFD study was conducted. In the CFD study, a droplet was released in a crossflow field that involved a pore opening and the contact angle was considered to decrease with time as a consequence of the leaching of affinity-enhancing agents. The CFD analysis revealed that the decrease in the contact angle resulted in the droplet spreading over the surface more. Furthermore, the interface that was formed at the entrance of the pore opening flattened as the contact angle decreased, leading the interface to advance more inside the pore. The droplet continued to pass over the pore opening until the contact angle reached a certain value, at which point, the droplet became pinned at the pore opening.
  • Editorial: Advanced modeling and simulation of flow in subsurface reservoirs with fractures and wells for a sustainable industry

    Sun, Shuyu; Edwards, Michael; Frank, Florian; Li, Jingfa; Salama, Amgad; Yu, Bo (Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, EDP Sciences, 2021-03-26) [Article]
    Flow in subsurface reservoirs is a crucial process in a wide range of applications at different time and space scales, such as petroleum exploration and recovery, groundwater contamination, subsurface carbon sequestration, and geothermal reservoir engineering. As an effective method, modeling and simulation of flow in subsurface reservoirs become essential components of many scientific and engineering applications in recent years. Significant advances have been made in this area, but accurate modeling and efficient, robust simulation still remain a challenging problem, especially for flow and transport in subsurface reservoirs with fractures and wells. To facilitate the exchange and dissemination of original research results and state-of-the-art reviews pertaining to flow in subsurface reservoirs with fractures and wells efficiently, we organized a special issue on “Advanced modeling and simulation of flow in subsurface reservoirs with fractures and wells for a sustainable industry” within Oil & Gas Science and Technology.
  • A Unified, One Fluid Model for the Drag of Fluid and Solid Dispersals by Permeate Flux Towards a Membrane Surface

    Salama, Amgad; Sun, Shuyu; Zhang, Tao (Membranes, MDPI AG, 2021-02-22) [Article]
    The drag of dispersals towards a membrane surface is a consequence of the filtration process. It also represents the first step towards the development of the problem of fouling. In order to combat membrane fouling, it is important to understand such drag mechanisms and provide a modeling framework. In this work, a new modeling and numerical approach is introduced that is based on a one-domain model in which both the dispersals and the surrounding fluid are dealt with as a fluid with heterogeneous property fields. Furthermore, because of the fact that the geometry of the object assumes axial symmetry and the configuration remains fixed, the location of the interface may be calculated using geometrical relationships. This alleviates the need to define an indicator function and solve a hyperbolic equation to update the configuration. Furthermore, this approach simplifies the calculations and significantly reduces the computational burden required otherwise if one incorporates a hyperbolic equation to track the interface. To simplify the calculations, we consider the motion of an extended cylindrical object. This allows a reduction in the dimensions of the problem to two, thereby reducing the computational burden without a loss of generality. Furthermore, for this particular case there exists an approximate analytical solution that accounts for the effects of the confining boundaries that usually exist in real systems. We use such a setup to provide the benchmarking of the different averaging techniques for the calculations of properties at the cell faces and center, particularly in the cells involving the interface.
  • Numerical Analysis of a Continuous Vulcanization Line to Enhance CH4 Reduction in XLPE-Insulated Cables

    Ruslan, Mohd Fuad Anwari Che; Youn, Dong Joon; Aarons, Roshan; Sun, Yabin; Sun, Shuyu (Materials, MDPI AG, 2021-02-21) [Article]
    Herein, we apply a computational diffusion model based on Fick’s law to study the manner in which a cable production line and its operating conditions can be enhanced to effectively reduce the CH4 concentration in cables insulated with cross-linked polyethylene (XLPE). Thus, we quantitatively analyze the effect of the conductor temperature, curing tube temperature distribution, transition zone length, and online relaxation on CH4 generation and transport during the production of 132 kV cables with an insulation thickness of 16.3 mm. Results show that the conductor temperature, which is initially controlled by a preheater, and the curing tube temperature distribution considerably affect the CH4 concentration in the cable because of their direct impact on the insulation temperature. The simulation results show 2.7% less CH4 remaining in the cable when the preheater is set at 160 C compared with that when no preheater is used. To study the curing tube temperature distribution, we consider three distribution patterns across the curing tube: constant temperature and linear incremental and decremental temperature. The amount of CH4 remaining in the cable when the temperature was linearly increased from 300 to 400 C was 1.6% and 3.7% lower than in the cases with a constant temperature at 350 C and a linear temperature decrease from 400 to 300 C, respectively. In addition, simulations demonstrate that the amount of CH4 removal from the cable can be increased up to 9.7% by applying an elongated and insulated transition zone, which extends the residence time for CH4 removal and decelerates the decrease in cable temperature. Finally, simulations show that the addition of the online relaxation section can reduce the CH4 concentration in the cable because the high cable temperature in this section facilitates CH4 removal up to 2.2%, and this effect becomes greater at low production speeds.
  • Image-based rock typing using local homogeneity filter and Chan-Vese model

    Wang, Yuzhu; Alzaben, Abdulaziz; Arns, Christoph H.; Sun, Shuyu (Computers and Geosciences, Elsevier BV, 2021-02-06) [Article]
    Image-based rock typing is carried out to classify an image of the heterogeneous rock sample into different rock types where each rock type can be treated as a homogeneous porous medium. In this study, we propose an innovative method for rock typing of the heterogeneous rock sample via three steps. First, the target image, a segmented binary image with two phases of pore and solid, is consecutively inputted into two filters of a local homogeneity filter and an average filter to increase the contrast between different rock types and decrease the contrast within each single rock type. Second, Chan-Vese model is applied to classify the filtered image into different rock types. Third, a thresholding is used to remove the particles, which are treated as noisy particles, smaller than a given preset size. The main idea of the local homogeneity filtering introduced in this study is undertaken by counting the number of pixels that possess the same phases as the center pixel within a 3 × 3 pixels neighborhood. This process is carried out iteratively, which means the previously estimated pixel will be used in the estimation of its neighbor unprocessed pixels. We demonstrate the application of the proposed method in several heterogeneous images and present good performance.
  • Dissociation and transport modeling of methane hydrate in core-scale sandy sediments: A comparative study

    Song, Rui; Feng, Xiaoyu; Wang, Yao; Sun, Shuyu; Liu, Jianjun (Energy, Elsevier BV, 2021-01-18) [Article]
    Better understanding of the dissociation and transport mechanism of methane hydrate in sandy sediments contributes to the future commercial extraction of hydrate. This paper presents a comparative study on the dissociation and transport modeling of methane hydrate in core-scale sandy sediments. The mathematical model is established considering the heat and mass transfer in the hydrate dissociation and the migration process of gas-water flow. The permeability model of the core is modified based on the lab test on the Berea sandstone, which is more feasible and physical than those by historical matching. The theoretical model is verified by comparing with experiments. The following improvements are achieved: 1) The distribution of the synthetic hydrate within the core in the lab is not uniform even when assuming the core is homogeneous. 2) Better agreements are acquired between the simulation and experimental data using the simulated initial distribution of the hydrate, water and methane in Masuda's experiment. 3) As the first effort in literature, the mini peak of the far-field pressure and the temperature fluctuation in Masuda's experiments are investigated by simulation, which reveals the physical reason for the phenomena. Moreover, this paper provides new insight into the modeling validation using Masuda's experiment for numerical simulation benchmarking.
  • Bulk and Interfacial Properties of Alkanes in the Presence of Carbon Dioxide, Methane, and Their Mixture

    Choudhary, Nilesh; Che Ruslan, Mohd Fuad Anwari; Nair, Arun Kumar Narayanan; Sun, Shuyu (Industrial & Engineering Chemistry Research, American Chemical Society (ACS), 2021-01-13) [Article]
    Molecular dynamics simulations were conducted to investigate the bulk and interfacial properties of alkanes in the presence of CH4, CO2, and their mixture under reservoir conditions. Theoretical analysis based on the predictive Peng− Robinson equation of state in combination with density gradient theory was used for comparison with the simulation results. Linear, branched, and cyclic alkanes (C7−C19) were considered for this study. We observed preferential dissolution in the alkane-rich phase and accumulation in the interfacial region of CO2 from the CH4/CO2 mixture. The solubility of CH4 and CO2 generally decreases with the number of carbon atoms in the alkane molecule n and are relatively lower in the presence of cycloalkanes. Our results show that at a fixed temperature and pressure, the interfacial tension (IFT) values of the CO2 + alkane system increase with the addition of CH4. These IFTs increase with n and are relatively higher in the presence of cycloalkanes. The cyclization effects are more important than branching effects for the bulk and interfacial properties of the studied systems. Our results may help to improve the understanding of the effects of impurities like CH4 on CO2enhanced oil recovery under reservoir conditions.
  • Image-based rock typing using grain geometry features

    Wang, Yuzhu; Sun, Shuyu (Computers & Geosciences, Elsevier BV, 2021-01) [Article]
    Image-based rock typing is carried out to quantitatively assess the heterogeneity of the reservoir specimen at a pore scale by classifying an image of a heterogeneous rock sample into a number of relatively homogeneous regions. Image-based rock typing can be treated as a special application of texture classification in the field of the digital core. In conventional texture classification algorithms, a single size window or a set of windows with different size are applied to scan the image to extract various local structure features, and then a classification algorithm is used to classify the image into different regions where each region possesses unique structure features. Due to the local features are extracted within a window, it is still challenging to identify the class of the voxels close to the boundary between different regions. In this paper, a rock typing method is proposed, which uses the geometry features of the grains instead of local structure features for classification. Inspired by the fact that in some cases the heterogeneity of the reservoir is mainly affected by the sedimentary process, which means each rock type always has certain specific grain features such as size and sphericity. To this kind of rock samples, the proposed grain-based rock typing algorithm can effectively address the boundary ambiguousness problem. In this study, the grains of the rock sample are partitioned firstly, and then their geometry features are calculated. Then a support vector machine algorithm is used to classify these grains into different rock types. Finally, the pore voxels are given a rock type, which is identical to its nearest grain. The proposed method shows excellent performance in the heterogeneous samples whose grains are available to be partitioned and distinguishable.
  • A Digital Twin for Unconventional Reservoirs: A Multiscale Modeling and Algorithm to Investigate Complex Mechanisms

    Zhang, Tao; Li, Yiteng; Cai, Jianchao; Meng, Qingbang; Sun, Shuyu; Li, Chenguang (Geofluids, Hindawi Limited, 2020-11-02) [Article]
    The special mechanisms underneath the flow and transport behaviors in unconventional reservoirs are still challenging an accurate and reliable production estimation. As an emerging approach in intelligent manufacturing, the concept of digital twin has attracted increasing attentions due to its capability of monitoring engineering processes based on modeling and simulation in digital space. The application potential is highly expected especially for problems with complex mechanisms and high data dimensions, because the utilized platform in the digital twin can be easily extended to cover more mechanisms and solve highly complicated problems with strong nonlinearity compared with experimental studies in physical space. In this paper, a digital twin is designed to numerically model the representative mechanisms that affect the production unconventional reservoirs, such as capillarity, dynamic sorption, and injection salinity, and it incorporates multiscale algorithms to simulate and illustrate the effect of these mechanisms on flow and transport phenomena. The preservation of physical laws among different scales is always the first priority, and simulation results are analyzed to verify the robustness of proposed multiscale algorithms.
  • Numerical investigation of carbonate acidizing with gelled acid using a coupled thermal–hydrologic–chemical model

    Liu, Piyang; Li, Jingfa; Sun, Shuyu; Yao, Jun; Zhang, Kai (International Journal of Thermal Sciences, Elsevier BV, 2020-10-23) [Article]
    In this work, an experiment-based rheological model that accounts for the influence of polymer concentration, shear-thinning behavior, and temperature variation on the in-situ viscosity of gelled acid is developed. On the basis of the rheological model, we present a thermal–hydrologic–chemical coupled model that describes the dissolution process of carbonate acidization with gelled acid. A sensitivity analysis of the dissolution dynamic regarding the temperature variation, polymer adsorption, and non-Newtonian behavior of the injected acid is carried out. The comparison of acidization curves and dissolution patterns obtained by injecting gelled acid and HCl is conducted. It is found that the optimal dissolution regime for gelled acid has a much wider range than neat HCl. It is observed from the numerical simulations that reservoir temperature and rheological parameters of the acid are key factors that affect acidizing efficiency, while the effect of polymer adsorption can be ignored. In addition, several recommendations for optimal stimulation of carbonates with gelled acids are provided.
  • Influence of fractal surface roughness on multiphase flow behavior: Lattice Boltzmann simulation

    Liu, Yang; Zou, Shuangmei; He, Ying; Sun, Shuyu; Ju, Yang; Meng, Qingbang; Cai, Jianchao (International Journal of Multiphase Flow, Elsevier BV, 2020-10-22) [Article]
    Accurate characterization of surface roughness and understanding its influence on multiphase flow behavior are important for industrial and environmental applications such as enhanced oil recovery, CO2 geological sequestration, and remediation of contaminated aquifers. Although some experimental and simulation studies have been conducted for investigating surface roughness in regular geometry structures, a more realistic description of roughness and its quantitative influence on multiphase flow need to be further explored. In this study, an optimized color-gradient lattice Boltzmann model is applied to simulate the steady-state two-phase flow in two-dimensional porous media modeled by a fourth-order Sierpinski carpet. The model is validated by comparing with the analytical solution and literature results, indicating reliability of our method. Then, rough surfaces with different roughness height and surface fractal dimension are characterized by a modified Weierstrass-Mandelbrot function and these effects on two-phase flow are investigated systematically by our model. The results show that the surface roughness has a negative effect on single-phase and two-phase fluid flow, which implies that the absolute and relative permeabilities for both wetting phase and nonwetting phase decreases with the increase of roughness height or surface fractal dimension. In addition, the surface roughness has influence on the two-phase distribution, velocity distribution and fluid-fluid/fluid-solid interface area, especially under the neutral wetting condition. Our study provides a pore-scale insight into the effect of surface roughness on two-phase flow, which is important for a fundamental understanding on macroscopic multiphase flow behaviors.
  • Bulk and Interfacial Properties of the Decane + Water System in the Presence of Methane, Carbon Dioxide, and Their Mixture

    Yang, Yafan; Nair, Arun Kumar Narayanan; Anwari Che Ruslan, Mohd Fuad; Sun, Shuyu (The Journal of Physical Chemistry B, American Chemical Society (ACS), 2020-10-16) [Article]
    Molecular dynamics simulations are carried out to study the two-phase behavior of the n-decane + water system in the presence of methane, carbon dioxide, and their mixture under reservoir conditions. The simulation studies were complemented by theoretical modeling using the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) and density gradient theory. Our results show that the presence of methane and carbon dioxide decreases the interfacial tension (IFT) of the decane + water system. In general, the IFT increases with increasing pressure and decreasing temperature for the methane + decane + water and carbon dioxide + decane + water systems, similar to what has been found for the corresponding decane + water system. The most important finding of this study is that the presence of carbon dioxide decreases the IFT of the methane + decane + water system. The atomic density profiles provide evidence of the local accumulation of methane and carbon dioxide at the interface, in most of the studied systems. The results of this study show the preferential dissolution in the water-rich phase and enrichment at the interface for carbon dioxide in the methane + carbon dioxide + decane + water system. This indicates the preferential interaction of water with carbon dioxide relative to methane and decane. Notably, there is an enrichment of the interface by decane at high mole fractions of methane in the methane/decane-rich or methane/carbon dioxide/decane-rich phase. Overall, the solubility of methane and carbon dioxide in the water-rich phase increases with increasing pressure and temperature. Additionally, we find that the overall performance of the PC-SAFT EoS and the cubic-plus-association EoS is similar with respect to the calculation of bulk and interfacial properties of these systems.
  • Stability theory of nano-fluid over an exponentially stretching cylindrical surface containing microorganisms.

    Ferdows, M; Hossan, Amran; Bangalee, M Z I; Sun, Shuyu; Alzahrani, Faris (Scientific reports, Springer Nature, 2020-10-12) [Article]
    This research is emphasized to describe the stability analysis in the form of dual solution of the flow and heat analysis on nanofluid over an exponential stretching cylindrical surface containing microorganisms. The research is also implemented to manifest the dual profiles of velocity, temperature and nanoparticle concentration in the effect of velocity ratio parameter ([Formula: see text]). Living microorganisms' cell are mixed into the nanofluid to neglect the unstable condition of nano type particles. The governing equations are transformed to non-linear ordinary differential equations with respect to pertinent boundary conditions by using similarity transformation. The significant differential equations are solved using build in function bvp4c in MATLAB. It is seen that the solution is not unique for vertical stretching sheet. This research is reached to excellent argument when found results are compared with available result. It is noticed that dual results are obtained demanding on critical value ([Formula: see text]), the meanings are indicated at these critical values both solutions are connected and behind these critical value boundary layer separates thus the solution are not stable.
  • An efficient multigrid-DEIM semi-reduced-order model for simulation of single-phase compressible flow in porous media

    Li, Jing Fa; Yu, Bo; Wang, Dao Bing; Sun, Shuyu; Sun, Dong Liang (Petroleum Science, Springer Nature, 2020-09-28) [Article]
    In this paper, an efficient multigrid-DEIM semi-reduced-order model is developed to accelerate the simulation of unsteady single-phase compressible flow in porous media. The cornerstone of the proposed model is that the full approximate storage multigrid method is used to accelerate the solution of flow equation in original full-order space, and the discrete empirical interpolation method (DEIM) is applied to speed up the solution of Peng–Robinson equation of state in reduced-order subspace. The multigrid-DEIM semi-reduced-order model combines the computation both in full-order space and in reduced-order subspace, which not only preserves good prediction accuracy of full-order model, but also gains dramatic computational acceleration by multigrid and DEIM. Numerical performances including accuracy and acceleration of the proposed model are carefully evaluated by comparing with that of the standard semi-implicit method. In addition, the selection of interpolation points for constructing the low-dimensional subspace for solving the Peng–Robinson equation of state is demonstrated and carried out in detail. Comparison results indicate that the multigrid-DEIM semi-reduced-order model can speed up the simulation substantially at the same time preserve good computational accuracy with negligible errors. The general acceleration is up to 50–60 times faster than that of standard semi-implicit method in two-dimensional simulations, but the average relative errors of numerical results between these two methods only have the order of magnitude 10−4–10−6%.
  • Accelerating flash calculations in unconventional reservoirs considering capillary pressure using an optimized deep learning algorithm

    Zhang, Tao; Li, Yiteng; Sun, Shuyu; Bai, Hua (Journal of Petroleum Science and Engineering, Elsevier BV, 2020-09-15) [Article]
    An increasing focus was placed in the past few decades on accelerating flash calculations and a variety of acceleration strategies have been developed to improve its efficiency without serious compromise in accuracy and reliability. Recently, as machine learning becomes a powerful tool to handle complicated and time-consuming problems, it is increasingly appealing to replace the iterative flash algorithm, due to the strong nonlinearity of flash problem, by a neural network model. In this study, an NVT flash calculation scheme is established with a thermodynamically stable evolution algorithm to generate training and testing data for the proposed deep neural network. With a modified network structure, the deep learning algorithm is optimized by carefully tuning neural network hyperparameters. Numerical tests indicate that the trained model is capable of accurately estimating phase compositions and states for complex reservoir fluids under a wide range of environmental conditions, while the effect of capillary pressure can be captured well. Thermodynamic rules are preserved well through our algorithm, and the trained model can be used for various fluid mixtures, which significantly accelerates flash calculations in unconventional reservoirs.
  • A Comprehensive Experimental Study on Mechanical Behavior, Microstructure and Transport Properties of 3D-printed Rock Analogs

    Song, Rui; Wang, Yao; Ishutov, Sergey; Zambrano-Narvaez, Gonzalo; Hodder, Kevin J.; Chalaturnyk, Rick J.; Sun, Shuyu; Liu, Jianjun; Gamage, Ranjith P. (Rock Mechanics and Rock Engineering, Springer Nature, 2020-09-08) [Article]
    3D-printed (3DP) analogs of natural rocks have been used in laboratory tests concerning geomechanical and transport properties. Rock analogs manufactured by 3D printing can be used to manufacture batch of the samples with specified heterogeneity compared to natural rocks. Rock analogs were manufactured with silica sand (SS) and gypsum powder (GP) using binder jetting as well as with coated silica beads (CSB) using selective laser curing. The uniaxial and triaxial compressive tests were conducted to investigate the strength and deformation characteristics of 3DP rocks that were quantitatively compared with natural rocks. CSB and SS specimens experienced tensile failure, while the GP specimen has shown shear failure and shear-expansion behavior. The microstructural characteristics (e.g. grain shape, pore type, and bonding form) of the SS specimen were similar to a natural sandstone (Berea sandstone reported in the literature) with a relatively loose texture. In addition, 3DP rocks were more permeable than Berea sandstone (permeability of SS, CSB, and Berea sandstone was 12580.5 mD, 9840.5 mD, and 3950 mD, respectively). The effect of microscopic mechanical behavior on macroscopic strength and failure characteristics was investigated using scanning electronic microscopy. CSB and SS specimens could be suitable to simulate the transport behavior of the highly permeable sedimentary rocks. The GP specimen could be used to study the large deformation characteristics and creep failure mode of highly stressed soft rocks. Despite the early stage of 3DP rock analog studies, the potential applications could be expanded by controlling the physical properties (e.g. wettability and surface roughness).
  • A 6M digital twin for modeling and simulation in subsurface reservoirs

    Sun, Shuyu; Zhang, Tao (Advances in Geo-Energy Research, Yandy Scientific Press, 2020-08-07) [Article]
    Modeling and simulation of flow, transport and geomechanics in the subsurface porous media is an effective approach to help make decisions associated with the management of subsurface oil and gas reservoirs, as well as in other wide application areas including groundwater contamination and carbon sequestration. Accurate modeling and efficient, robust simulation have always been the main purposes of reservoir researches, and a 6M digital twin (multi-scale, multidomain, multi-physics and multi-numerics numerical modeling and simulation of multi-component and multi-phase fluid flow in porous media) is designed, equipped with the following six pronounced features, to better digitally model and simulate the engineering processes and procedures in physical reality and further control and optimize such processes and procedures.
  • Construction of a minimum energy path for the VT flash model by an exponential time differencing scheme with the string method

    Zhang, Yuze; Li, Yiteng; Zhang, Lei; Sun, Shuyu (arXiv, 2020-08-07) [Preprint]
    Phase equilibrium calculation, also known as flash calculation, plays significant roles in various aspects of petroleum and chemical industries. Since Michelsen proposed his milestone studies in 1982, through several decades of development, the current research interest on flash calculation has been shifted from accuracy to efficiency, but the ultimate goal remains the same focusing on estimation of the equilibrium phase amounts and phase compositions under the given variable specification. However, finding the transition route and its related saddle points are very often helpful to study the evolution of phase change and partition. Motivated by this, in this study we apply the string method to find the minimum energy paths and saddle points information of a single-component VT flash model with the Peng-Robinson equation of state. As the system has strong stiffness, common ordinary differential equation solvers have their limitations. To overcome these issues, a Rosenbrock-type exponential time differencing scheme is employed to reduce the computational difficulty caused by the high stiffness of the investigated system. In comparison with the published results and experimental data, the proposed numerical algorithm not only shows good feasibility and accuracy on phase equilibrium calculation, but also successfully calculates the minimum energy path and and saddle point of the single-component VT flash model with strong stiffness.
  • Dual solution of boundary-layer flow driven by variable plate and streaming-free velocity

    Ferdows, M.; Alzahrani, Faris; Sun, Shuyu (Advances in Mechanical Engineering, SAGE Publications, 2020-07-22) [Article]
    This article presents a numerical study to investigate boundary-layer heat transfer fluid associated with a moving flat body in cooperation of variable plate and streaming-free velocity along the boundary surface in the laminar flow. The thermal conductivity is supposed to vary linearly with temperature. Similarity transformations are applied to render the governing partial differential equations for mass, momentum and energy into a system of ordinary differential equations to reveal the possible existence of dual solutions. MATLAB package has been used to solve the boundary value problem numerically. We present the effects of various parameters such as velocity ratio, thermal conductivity and variable viscosity on velocity and temperature distribution. The analysis of the results concerning Skin friction and Nusselt number near the wall is also presented. It is focused on the detection and description of the dual solutions. The study reveals that the undertaken problem admits dual solutions in particular range of values of different physical parameters. It can be seen that for the first branch solution, the fluid velocity decreases near the sheet, but it increases far away from the sheet for velocity ratio parameter, whereas the opposite effect is induced for second branch solution. Skin friction coefficient and rate of heat transfer increase due to increase in thermal conductivity parameter.
  • Effect of salinity on oil production: review on low salinity waterflooding mechanisms and exploratory study on pipeline scaling

    Zhang, Tao; Li, Yiteng; LI, CHENGUANG; Sun, Shuyu (Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, EDP Sciences, 2020-07-21) [Article]
    The past decades have witnessed a rapid development of enhanced oil recovery techniques, among which the effect of salinity has become a very attractive topic due to its significant advantages on environmental protection and economical benefits. Numerous studies have been reported focusing on analysis of the mechanisms behind low salinity waterflooding in order to better design the injected salinity under various working conditions and reservoir properties. However, the effect of injection salinity on pipeline scaling has not been widely studied, but this mechanism is important to gathering, transportation and storage for petroleum industry. In this paper, an exhaustive literature review is conducted to summarize several well-recognized and widely accepted mechanisms, including fine migration, wettability alteration, double layer expansion, and multicomponent ion exchange. These mechanisms can be correlated with each other, and certain combined effects may be defined as other mechanisms. In order to mathematically model and numerically describe the fluid behaviors in injection pipelines considering injection salinity, an exploratory phase-field model is presented to simulate the multiphase flow in injection pipeline where scale formation may take place. The effect of injection salinity is represented by the scaling tendency to describe the possibility of scale formation when the scaling species are attached to the scaled structure. It can be easily referred from the simulation result that flow and scaling conditions are significantly affected if a salinity-dependent scaling tendency is considered. Thus, this mechanism should be taken into account in the design of injection process if a sustainable exploitation technique is applied by using purified production water as injection fluid. Finally, remarks and suggestions are provided based on our extensive review and preliminary investigation, to help inspire the future discussions.

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