Schulich School of Engineering
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With an annual average of 25 internationally recognized research chairs, more than 160 faculty members and 1,200 graduate students, the Schulich School of Engineering at the University of Calgary is a powerhouse of research and innovation.
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Browsing Schulich School of Engineering by Department "Chemical & Petroleum Engineering"
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Item Open Access Accelerating the GMRES solver with block ILU(k) preconditioner on GPUs in reservoir simulation(Journal of Geology & Geosciences, 2015) Chen, Zhangxing (John); Liu, H.; Yang, B.This paper studies the parallelization of the restarted GMRES solver, GMRES (m), and the block ILU (k) preconditioner on GPUs used in petroleum reservoir simulations. The difficulty is how to accelerate this preconditioner with a variable block size. In this paper, parallel solution techniques for block triangular systems are proposed, which work for matrices with an arbitrary block size. These techniques also work with an arbitrary level k for the block ILU (k) preconditioner. Numerical experiments show that the GPU-based linear solver GMRES (m) is much faster than its CPU version.Item Open Access Application and experimental study of cyclic foam stimulation(RSC (Royal Society of Chemistry) Advances, 2015-08-27) Chen, Zhangxing (John); Zhang, J.; Wu, X.; Han, G.; Wang, J.; Ren, Z.; Zhang, K.Formation damage is a serious problem in oil and gas industries. Based on common reservoir damage, the conditions and factors resulting in damage were summarized into four categories in this paper. The worldwide advanced technologies applied in reservoir damage treatment are reviewed. For the first time, we propose the concept of injecting nitrogen foam into a formation to treat the damage caused by sand blocking. An application of Cyclic Foam Stimulation is introduced, which enhances productivity significantly. Experimental apparatus for the Cyclic Foam Stimulation was designed, which included a wellbore vessel that could stimulate the effect of sand setting. A reservoir vessel was also designed to supply the foam. Additionally, in order to simulate the formation damage caused by the size and distribution of fine sand, six artificial cores, which were porosity contrastive and sand producing, were prepared based on the technologies of pressure control and PVA membrane wrapping. The experimental results show that the foam has a good discharging effect on sand blockages. Moreover, the effects of the size and distribution of the fine sand on the porosity was studied. It was found that the smaller the size of the grains and the more uniform the grain distribution, the worse the formation porosity. A porosity recovery factor has been defined and the recovery rate of the porosity was also studied. A scientific guide for the application of Cyclic Foam Stimulation can be generated from the studies in this paper.Item Open Access Capillary forces between two parallel plates connected by a liquid bridge(Journal of Porous Media, 2015) Chen, Zhangxing (John); Dejam, M.; Hassanzadeh, H.Liquid flow between porous and nonporous materials plays an important role in many science and engineering applications such as oil recovery from fractured porous media. The capillary continuity between porous matrix blocks via formation of liquid bridges is a key contributor to the gas−oil gravity drainage mechanism in a gas invaded zone of naturally fractured reservoirs, which increases the height of the continuous liquid column in a fractured formation, thereby enhancing the recovery of oil. However, the role of capillary forces information or break-up of liquid bridges between porous matrix blocks remains a controversial topic. In an attempt to improve an understanding of this problem, a force balance is presented for the concave liquid bridges formed between two horizontal parallel plates. The force balance allows development of a simple model that can be used to find a relationship between the net capillary force, contact angle, and liquid bridge volume. Three different regions including: (I) repulsive net capillary force, (II) attractive net capillary force, and (III) nonexistence regions have been identified. Region I is considered as a region of liquid bridge break-up while Region II is considered as a region of liquid bridge formation. The findings improve an understanding of the formation and break-up of the liquid bridges, which is important in oil recovery from naturally fractured reservoirs during a gravity drainage process.Item Open Access CO2 Gasification of Sugarcane Bagasse Char: Consideration of Pyrolysis Temperature, Silicon and Aluminum Contents, and Potassium Addition for Recirculation of Char(2020-11-24) Motta, Ingrid Lopes; Arnold, Ross A.; Lopez-Tenllado, Francisco Javier; Filho, Rubens Maciel; Wolf Maciel, Maria Regina; Hill, Josephine M.In sugarcane bagasse gasification, char recirculation to the gasifier improves the syngas quality and process efficiency. To determine the effect of char properties on the reaction kinetics, in this work, the pregasification pyrolysis temperature, particle size, and catalyst (potassium) loading were varied. Char samples were prepared at 750–900 °C via pyrolysis and gasified isothermally in a thermogravimetric analysis unit at 850 °C with CO2, and gasification data were modeled using the random pore and extended random pore models. Increasing pyrolysis temperatures did not affect the char morphology and surface composition but did reduce the surface area, as determined by N2 adsorption, decreasing initial gasification rates, and the overall fitted rate constants. Reduction of the particle size via ball milling decreased the time required for complete conversion and changed the shape of the rate versus conversion curves from monotonically decreasing to concave down. The char sample prepared via pyrolysis at 900 °C was an exception, having a maximum rate at ∼10% conversion without ball milling. After ball milling of the char sample prepared at 750 °C, there was an accumulation of ash (Al and Si) on the surface of the particles and a reduction in the surface area, consistent with the ash blocking pores—the porosity in these samples increased during the initial stages (up to ∼20% conversion) of gasification. The gasification behavior was generally well modeled by the extended random pore model. Although the addition of KOH (K/Al mass ratio ∼ 0.2–1.25) enhanced the gasification rates, too much K—from the addition of KOH or after 90% conversion—created mass-transfer limitations resulting in lower gasification rates.Item Open Access Development of a Thermal Wellbore Simulator with Focus on Improving Heat Loss Calculations for SAGD Steam Injection(SPE Reservoir Evaluation & Engineering, 2016) Chen, Zhangxing (John); Xiong, Wanqiang; Bahonar, Mehdi; Dong, ChaoTypical thermal processes involve sophisticated wellbore configurations, complex fluid flow and heat transfer in tubing, annulus, wellbore completion, and surrounding formation. Despite notable advancements made in wellbore modeling, accurate heat loss modeling is still a challenge using the existing wellbore simulators. This challenge becomes even greater when complex but common wellbore configurations such as multi-parallel or multi-concentric tubings are used in thermal processes such as Steam Assisted Gravity Drainage (SAGD). To improve heat loss estimation, a standalone fully-implicit thermal wellbore simulator is developed that can handle several different wellbore configurations and completions. This simulator uses a fully implicit method to model heat loss from tubing walls to the surrounding formation. Instead of implementing the common Ramey method (1962) for heat loss calculations that has been shown to be a source of large errors, a series of computational fluid dynamical (CFD) models are run for the buoyancy driven flow for different annulus sizes and lengths and numbers of tubings. Based on these CFD models, correlations are derived that can conveniently be used for the more accurate heat loss estimation from the wellbore to the surrounding formation for SAGD injection wells with single or multiple tubing strings. These correlations are embedded in the developed wellbore simulator and results are compared with other heat loss modeling methods to demonstrate its improvements. A series of validations against commercial simulators and field data are presented in this paper.Item Open Access Dynamics of viscous liquid bridges inside microchannels subject to external oscillatory flows(Physical Review E, 2015-02) Chen, Zhangxing (John); Ahmadlouydarab, M.; Azaiez, J.We report on two-dimensional simulations of liquid bridges' dynamics inside microchannels of uniform wettability and subject to an external oscillatory flow rate. The oscillatory flow results in a zero net flow rate and its effects are compared to those of a stationary system. To handle the three phase contact lines motion, Cahn-Hilliard diffuse-interface formulation was used and the flow equations were solved using the finite element method with adaptively refined unstructured grids. The results indicate that the liquid bridge responds in three different ways depending on the substrate wettability properties and the frequency of the oscillatory flow. In particular below a critical frequency, the liquid bridge will rupture when the channel walls are philic or detach from the surface when they are phobic. However, at high frequencies, the liquid bridge shows a perpetual periodic oscillatory motion for both philic and phobic surfaces. Furthermore, an increase in the frequency of the flow velocity results in stabilization effects and a behavior approaching that of the stationary system where no rupture or detachment can be observed. This stable behavior is the direct result of less deformation of the liquid bridge due to the fast flow direction change and motion of contact lines on the solid substrate. Moreover, it was found that the flow velocity is out of phase with the footprint and throat lengths and that the latter two also show a phase difference. These differences were explained in terms of the motion of the two contact lines on the solid substrates and the deformation of the two fluid-fluid interfaces.Item Open Access Effects of fracture geometries on well production in hydraulic fractured tight oil reservoirs(Journal of Canadian Petroleum Technology, 2015-05) Chen, Zhangxing (John); Lin, M.; Chen, S.; Ding, W.; Xu, J.Tight oil production is emerging as an important new source of energy supply and has reversed a decline in US crude-oil production and western Canadian light-oil production. At present, the combination of the multistage hydraulic fracturing and horizontal wells has become a widely used technology in stimulating tight oil reservoirs. However, the ideal planar fractures used in the reservoir simulation are simplified excessively. Effects of some key fracture properties (e.g., fracture-geometry distributions and the permeability variations) are not usually taken into consideration during the simulation. Oversimplified fractures in the reservoir model may fail to represent the complex fractures in reality, leading to significant errors in forecasting the reservoir performance. In this paper, we examined the different fracture-geometry distributions and discussed the effects of geometry distribution on well production further. All fracture-geometry scenarios were confined by microseismic-mapping data. To make the result more reliable and relevant, a geomodel was first constructed for a tight oil block in Willesden Green oil field in Alberta, Canada. The simulation model was then generated on the basis of the geomodel and history matched to the production history of vertical production wells. A horizontal well was drilled in the simulation model, and different fracture-geometry scenarios were analyzed. Results indicated that the simulation results of simple planar fractures overestimated the oil rate and led to higher oil recoveries. In addition, if the secondary fracture can achieve the same permeability as the main fracture, a hydraulic fracture with branches can increase the well production (e.g., Scenario 2 under the conductivity ratio of 1:2) because of a larger effective contact area between matrix and fracture. Secondary fractures with low permeability can decrease the well productivity compared with wells with biwing planar fractures. Furthermore, the effect of hydraulic-fracture geometries on the cumulative production of the wells with higher main-fracture conductivity was more significant compared with those with lower main-fracture conductivity.Item Open Access Equation of state for methane in nanoporous material at supercritical temperature over a wide range of pressures(Nature: Scientific Reports 6, 2016-01) Chen, Zhangxing (John); Wu, K.; Li, X.; Dong, X.The methane storage behavior in nanoporous material is significantly different from bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores wall to the methane intermolecular interaction, and the geometric constraint. By linking the macroscopic properties of methane storage to the microscopic properties of methane molecules-nanopores wall molecules system, we develop an equation of state for methane at supercritical temperature over a wide range of pressure. Molecular dynamic simulation data demonstrate that this equation is able to relate very well the methane storage behavior with each of key physical parameters, including pore size, shape, wall chemistry and roughness. Moreover, this equation only requires one fitted parameter, and is simply and powerful in application.Item Open Access First-order decoupled method of the three-dimensional primitive equations of the ocean(SIAM Scientific Computing, 2016) Chen, Zhangxing (John); He, Y.; Zhang, Y.; Xu, H.This paper is concerned with a first-order fully discrete decoupled method for solving the three-dimensional (3D) primitive equations of the ocean with the Dirichlet boundary conditions on the side, where a decoupled semi-implicit scheme is used for the time discretization, and the $P_1(P_1)-P_1-P_1(P_1)$ finite element for velocity, pressure, and density is used for the spatial discretization of these equations. The $H^1-L^2-H^1$ optimal error estimates for the numerical solution $(u_h^n,p_h^n,\theta_h^n)$ and the $L^2$ optimal error estimate for $(u^n_h,\theta_h^n)$ are established under the restriction of $0Item Open Access Fluorescent polycatecholamine nanostructures as a versatile probe for multiphase systems(RSC Advances, 2018-09-13) Ozhukil Kollath, Vinayaraj; Derakhshandeh, Maziar; Mudigonda, Thanmayee; Islam, Muhammad Naoshad; Trifkovic, Milana; Karan, Kunal; Mayer, Francis D.Shape and size controlled nanostructures are critical for nanotechnology and have versatile applications in understanding interfacial phenomena of various multi-phase systems. Facile synthesis of fluorescent nanostructures remains a challenge from conventional precursors. In this study, bio-inspired catecholamines, dopamine (DA), epinephrine (EP) and levodopa (LDA), were used as precursors and fluorescent nanostructures were synthesized via a simple one pot method in a water–alcohol mixture under alkaline conditions. DA and EP formed fluorescent spheres and petal shaped structures respectively over a broad spectrum excitation wavelength, whereas LDA did not form any particular structure. However, the polyepinephrine (PEP) micropetals were formed by weaker interactions as compared to covalently linked polydopamine (PDA) nanospheres, as revealed by NMR studies. Application of these fluorescent structures was illustrated by their adsorption behavior at the oil/water interface using laser scanning confocal microscopy. Interestingly, PDA nanospheres showed complete coverage of the oil/water interface despite its hydrophilic nature, as compared to hydrophobic PEP micropetals which showed a transient coverage of the oil/water interface but mainly self-aggregated in the water phase. The reported unique fluorescent organic structures will play a key role in understanding various multi-phase systems used in aerospace, biomedical, electronics and energy applications.Item Open Access Impact of particle size and catalyst dispersion on gasification rates measured in a thermogravimetric analysis unit: Case study of carbon black catalyzed by potassium or calcium(2020-11-19) Arnold, Ross A.; Motta, Ingrid L.; Hill, Josephine M.Gasification is often studied in the laboratory using a thermogravimetric analysis (TGA) unit with less than 1 g of sample in order to obtain intrinsic rates. Many studies, however, neglect to consider the impact of particle size, of both the gasification feed and the catalyst, and catalyst dispersion on the measured rates. The impact of these factors was demonstrated using catalytic gasification of carbon black, an ash-free feed, as a case study, with K2CO3 or CaCO3 as catalysts at 850 °C in a CO2 atmosphere. Hand-mixing and ball-milling were used to alter the initial parameters. Ball-milling reduced both the particle size of both species and increased the catalyst dispersion, resulting in higher interfacial areas and gasification rates than hand-mixing. The changes in gasification kinetics were estimated by modeling the rates using the random pore and extended random pore models (RPM and eRPM, respectively). The impact of the interfacial contact area between carbon and catalysts (varied by particle size and mixing method) was dependent on the activity of the catalyst with the more active (potassium) catalyst being less affected. CaCO3 was found to sinter at 850 °C, reducing available catalytic surface area and blocking CO2 access to the carbon feed. It is recommended to consider these factors in future studies and to always report the particle sizes used.Item Metadata only An integrated geology and reservoir engineering approach for modeling of a giant fractured basement reservoir(International Journal of Oil, Gas and Coal Technology, 2015) Chen, Zhangxing (John); Dang, Cuong; Nguyen, Ngoc; Phung, T.A great portion of the world's oil reserves is contained in naturally fractured reservoirs (NFRs). As the conventional oil and gas reservoirs have become significantly depleted whereas energy demand sharply increases, the NFRs play an important role in oil exploration and make a large contribution toward oil and gas production worldwide. This paper aims to introduce a historical case study of a successful development plan for a giant fractured granite basement reservoir with a unique geological characterisation. A better geological understanding about the complexity of such a naturally fractured basement reservoir is provided within a simulation strategy in order to optimise successfully its oil exploitation. With our rich experiences in exploration and production of hydrocarbons in fractured basement granite rock for more than 20 years, it is a valuable case study for both current and future development planning of basement reservoirs elsewhere in the world.Item Open Access Numerical study using explicit multistep Galerkin finite element method for the MRLW equation(Numerical Methods for Partial Differential Equations, 2015-03-05) Chen, Zhangxing (John); Mei, L.; Gao, Y.In this article, an explicit multistep Galerkin finite element method for the modified regularized long wave equation is studied. The discretization of this equation in space is by linear finite elements, and the time discretization is based on explicit multistep schemes. Stability analysis and error estimates of our numerical scheme are derived. Numerical experiments indicate the validation of the scheme by L2– and L∞– error norms and three invariants of motion.4Item Open Access On the comparison of properties of Rayleigh waves in elastic and viscoelastic media(International Journal of Numerical Analysis and Modeling, 2011) Chen, Zhangxing (John); He, Y.; Gao, J.Dispersion properties of Rayleigh‐type surface waves can be used for imaging and characterizing the shallow subsurface. This paper uses the time‐domain finite difference method on the Rotated staggered grid to simulates Rayleigh waves in complex viscoelastic media. The second‐order displacement‐stress viscoelastic wave equations are used in the computational domain and the unsplit convolutional perfectly matched layer is used as the absorbing boundary condition. The elastic wave‐fields in a two‐layer model is simulated to prove the correctness of this scheme. The viscoelastic Rayleigh waves are calculated and the dispersion properties are analyzed. The dispersion curve changes with different values of quality factor Q in the media and higher modes of Rayleigh waves are generated and possess significant amounts of energy with strong attenuation.Item Open Access Preconditioned GMRES solver on multiple GPU architecture(Computers and Mathematics with Applications, 2016-08) Chen, Zhangxing (John); Yang, B.; Liu, HuiIn this paper, we analyze the preconditioned GMRES algorithm in detail and decompose it into components to implement on multiple-GPU architecture. The operations of vector updates, dot products and Sparse Matrix-Vector multiplication (SpMV) are implemented in parallel. In addition, a specific communication mechanism for SpMV is designed. The preconditioner is established on the host (CPU) and solved on the devices (GPUs). Validated by a series of numerical experiments, the GPU-based GMRES solver is effective and favorable parallel performance is achieved.Item Open Access A pseudo-bubble point model and its simulation for foamy oil in porous media(SPE Journal, 2015-04) Chen, Zhangxing (John); Sun, J.; Wang, R.; Wu, X.This is the second paper of a series in which we study heavy oil in porous media. The first paper dealt with an experimental study (Wang et al. 2008), whereas a mathematical and simulation study is presented here. The research program stems from the need to predict the field performance of a class of heavy-foamy-oil reservoirs. These reservoirs show a better-than-expected primary performance: lower production gas/oil ratios (GORs), higher-than-expected production rates, and higher oil recovery. A mechanism used to account for the observed performance is that the liberated solution gas is entrained in the oil when the reservoir pressure falls below the thermodynamic equilibrium bubblepoint pressure. The presence of entrained gas increases the effective compressibility of the oil phase and prevents gas from becoming a free phase. Hence, the foamy oil behaves as if it has a pseudobubblepoint pressure below the usual equilibrium bubblepoint pressure. This paper describes a pseudobubblepoint model and a methodology that can be used to compute foamy-oil fluid properties from conventional laboratory pressure/volume/temperature (PVT) data. The techniques developed are then used to study foamy oil in the Orinoco belt, Venezuela. The present mathematical model is validated by comparing numerical and experimental results.Item Open Access Review of the Effect of Temperature on Oil-Water Relative Permeability in Porous Rocks of Oil Reservoirs(Elsevier Ltd., 2018-09-22) Esmaeili, Sajjad; Sarma, Helmanta Kumar; Harding, Thomas Grant; Maini, B. B.Thermal methods of heavy oil recovery involve multi-phase flow at high temperatures. Numerical simulation studies of such processes require accounting for changes in the multi-phase flow behavior of the rock-fluid system with increasing temperature. Although the effect of temperature on two-phase relative permeability has been studied for more than five decades, it remains an unresolved issue. Experimental results that frequently contradict each other are still being reported and the issue remains a matter of debate. The purpose of this review is to critically examine the reported results and explore the possible reasons for contradictory results. We have examined the reported results of more frequently-cited papers from past five decades and attempted to rationalize the disagreements in findings. There appear to be three main reasons for the lack of consensus in experimentally observed results. The measurements of relative permeability at high temperature are complex and the reported results often include experimental artifacts. Secondly, meaningful relative permeability measurements require that capillary forces control the fluid distribution within the pore space, but this condition is difficult to ensure in viscous oil systems. The third reason is that the impact of temperature is not same in all rock-fluid systems, it depends on how the wettability, interfacial tension and the pore geometry changes with temperature. It becomes apparent that it is not advisable to generalize the effect of temperature on relative permeability from previous studies without having a good understanding of how the underlying parameters that can influence the relative permeability are changing with temperature. The relative permeability of a specific petroleum reservoir may (or may not) vary with temperature.Item Open Access Solid acid catalysts produced by sulfonation of petroleum coke: Dominant role of aromatic hydrogen(2020-06-01) Xiao, Ye; Hill, Josephine M.Carbon based solid waste materials have been intensively investigated for the preparation of solid acid catalysts through sulfonation, but the acidity varies significantly depending on the material. In this study, the role of aromatic hydrogen in sulfonation with concentrated H2SO4 was investigated using petroleum coke (petcoke), graphite, and biochar as the carbon materials. Through ball milling and calcination, the amount of aromatic hydrogen on the petcoke could be increased or decreased, respectively. After sulfonation at 80 °C with concentrated H2SO4, the produced acidity (i.e., –SO3H groups) increased as the amount of aromatic hydrogen increased from essentially no acidity on graphite to 0.55 mmol/g on biochar and 1.25 mmol/g on petcoke (particle sizes of 45–90 μm) indicating the importance of aromatic hydrogen during sulfonation. Calcination (350 °C for 1 h) of the petcoke before sulfonation decreased the acidity to 0.59 mmol/g, while ball milling (with isopropanol and silica for 24 h) increased the acidity to 3.73 mmol/g. The sulfonated petcoke samples were used as catalysts for the esterification reaction between octanoic acid and methanol at 60 °C and the turnover frequencies were 48–85 h−1. The results give insights on the preparation of solid acid catalysts from carbon materials and highlight the application of petcoke without activation as a feedstock for esterification catalysts.Item Open Access Stability of fluorosurfactant absorption on mineral surface for water removal in tight gas reservoirs(Journal of Chemistry, vol. 2015, 2015) Chen, Zhangxing (John); You, L.; Zhang, W.; Kang, Y.; Liu, X.Long-term effectiveness of rock wettability alteration for water removal during gas production from tight reservoir depends on the surfactant adsorption on the pore surface of a reservoir. This paper selected typical cationic fluorosurfactant FW-134 as an example and took advantage of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM) to investigate its adsorption stability on the rock mineral surface under the oscillation condition at high temperature for a long time. The experimental results indicate that the F element content on the sample surface increases obviously, the surface structure of fluorine-carbonization also undergoes a significant change, and the fluorine surfactant exhibits a good interfacial modification and wettability alteration ability due to its adsorption on the pore surface transforming the chemical structure of the original surface. The adsorption increases indistinctly with the concentration of over 0.05% due to a single layer adsorption structure and is mainly electrostatic adsorption because the chemical bonding between the fluorosurfactant and the rock mineral surface, the hydrogen bonding, is weak and inconspicuous.Item Open Access Stabilized finite element methods for a blood flow model of arterosclerosis(Numerical Methods for Partial Differential Equations, 2015-09-21) Chen, Zhangxing (John); Jing, F.; Li, J.In this article, a blood flow model of arteriosclerosis, which is governed by the incompressible Navier–Stokes equations with nonlinear slip boundary conditions, is constructed and analyzed. By means of suitable numerical integration approximation for the nonlinear boundary term in this model, a discrete variational inequality for the model based on math formula stabilized finite elements is proposed. Optimal order error estimates are obtained. Finally, numerical examples are shown to demonstrate the validity of the theoretical analysis and the efficiency of the presented methods.