Sharif Digital Repository

Finesmigration is a noticeable problem in petroleum-production engineering. Plugging of throats in porous media occurs because of detachment of fine particles from sand surfaces. Thus, the study of interactions between fines and pore surfaces and the investigation of governing forces are important factors to consider when describing the mechanism of the fines-release process. The main types of these forces are electric double-layer repulsion (DLR) and London-van der Waals attraction (LVA). It may be possible to alter these forces with nanoparticles (NPs) as surface coatings. In comparison with repulsion forces, NPs increase the effect of attraction forces. In this paper, we present new... 

In this article a double-inlet pulse-tube refrigerator (DIPTR) is modeled using the nodal analysis technique. The main complexity of the problem is oscillatory and unsteady characteristics of the flow. Solving the flow field in the regenerator section of the system as a porous medium with nonlocal thermal equilibrium is challenging. Governing equations are developed applying mass, energy, and momentum equations to different finite volumes in each component of DIPTR. A numerical code (SharifPTR), with graphical user interface, has been developed to investigate the influence of geometrical and working parameters on performance. The governing equations are a system of boundary value problems.... 

Multiscale finite volume (MSFV) method have been developed and applied in various complicated physics. The most important advantage of MSFV method is its computational efficiency. In this paper we present a new set of boundary condition for calculation of basis and correction functions which leads to further reduction in computational time in problems with medium heterogeneity and therefore improves computational efficiency. In standard MSFV (sMSFV) method reduced boundary condition is used to determine the basis and correction functions which is based on local information, however in modified MSFV (mMSFV) method global information is used at initial time for constructing boundary condition... 

In this investigation, an accurate high pressure and temperature diffusion setup was applied to measure the diffusion coefficients of methane in Iranian heavy oils in presence and absence of porous media by using the pressure-decay method. The solvent diffusivity in heavy oil was determined by both graphical and numerical methods. In addition, the effects of the porous medium and the temperature on the molecular diffusion coefficient of the solvent gas in the liquid phase were discussed and finally, using experimental data, a functionality dependence of molecular diffusivity on temperature and porous medium characteristics was proposed  

A vast amount of death in the world has been attributed to atherosclerosis. This disease causes plaque formation and finally lack of blood supply to an organ. The prominent aim of this study is proposing an accurate and simple model to investigate the process of arterial wall thickening. In order to investigate LDL (low density lipoprotein) accumulation in arterial wall which is considered the first stage of atherosclerosis, a four layer model for arterial wall consisting of endothelium, intima, IEL and media is presented. All layers are treated as homogenous porous media. The four-layer arterial wall model is the most powerful and reliable tool for modeling LDL transport within arterial... 

Oil production from asphaltenic oil reservoirs has always encountered difficulties, such as plugging and unpredictable fluid properties. To physically recognize the aspects of asphaltene deposition, several dynamic and static asphaltene deposition tests were designed and performed on one of the giant south Iranian oil reservoirs using dead and live crude oil and real core samples. Moreover, the effects of fluid velocity on the extent of damage were investigated. It was found that surface deposition of asphaltene particles is the main source of formation damages in the porous media and the resulting permeability impairment obeys an exponential behavior. All of the experiments confirm that... 

Coupling the adjacent zones for seepage analysis in porous media needs compatibility and equilibrium equations (equality of potential on coinciding nodes and conservation of flowing mass between zones, respectively). When stretched coordinate transformation is applied to the anisotropic zones, the Dirichlet boundary conditions remain unchanged, but the Neumann boundary condition should also be transformed. Similarly in a zoned problem, for the interface between zones, compatibility equations remain unchanged during the transformation while the equilibrium equations should be transformed. In this paper, transformed Neumann boundary conditions and equilibrium equations for the interface of... 

Analytical solution of shock wave propagation in pure gas in a shock tube is usually addressed in gas dynamics. However, such a solution for granular media is complex due to the inclusion of parameters relating to particles configuration within the medium, which affect the balance equations. In this article, an analytical solution for isothermal shock wave propagation in an isotropic homogenous rigid granular material is presented, and a closed-form solution is obtained for the case of weak shock waves. Fluid mass and momentum equations are first written in wave and (mathematical) non-conservation forms. Afterwards by redefining the sound speed of the gas flowing inside the pores, an... 

Zirconia/Hydroxyapatite composites containing 20-50 wt.% 8YSZ were prepared on Ti/TiO2 substrates by electrophoretic deposition (EPD)/micro-arc oxidation (MAO) process. Titania, as an inner layer, was grown on the Ti plates using MAO treatment in order to form a strong join between substrate and HAp. These composites were produced by EPD in ethanol containing ZrO2/HAp particles at 50, 100 and 150 V in 1 min. Asprepared samples were sintered at 900, 1100 and 1300 °C. HAp, β-TCP, CaZrO3 phases were identified using X-ray diffractometry analysis (XRD). Scanning electron microscopy (SEM) utilized to study the surface morphology indicated a crack free microstructure at 1300 °C  

This paper investigates numerical simulation of one-dimensional homogeneous adiabatic gas-liquid two-phase flow in a rectangular microchannel with one boundary porous wall under the assumption of hydrophobic condition. Gas enters the microchannel with a uniform velocity and liquid is injected through the porous side wall. The present approach is to simulate water injection effects and developing mechanism of two-phase flow. The modeling and solution of the conservation equations provide pressure drop, vapor quality, void fraction and tow-phase mixture velocity for different water injection rates. The results show that velocity and pressure drop significantly perturbed when the water... 

In this paper, combined forced and natural convection in a vertical channel containing both porous and viscous regions taking into account the influences of inertial force and viscous dissipation has been studied. In this regard, fully developed fluid flow in the porous region was modeled using the Brinkman-Forchheimer extended Darcy model. To solve governing equations of both the porous and viscous regions including thermal energy and momentum equations, a two-parameter perturbation method was applied. The velocity and temperature distributions of both the regions were obtained in terms of various parameters such as inertial force, Grashof, Reynolds, and Brinkman numbers, as well as various... 

Porous medium characteristics (e.g., pore geometry and medium heterogeneity) as well as the chemical nature of the co-solvents crucially affect the oil displacement efficiency during solvent flooding processes. In this work, initially saturated models with heavy crude oil were used to perform a series of solvent injection experiments. Several onequarter five-spot micromodels with pre-designed pore geometry were constructed and used. In addition, rock-look-alike flow patterns generated from thin sections of sandstone and dolomite reservoir rocks were etched onto glass plates to form micromodels mimicking the pore geometry and heterogeneity of these rocks. Four different groups of chemicals... 

This work presents results from two sets of experiments conducted to study, in pore level, the role of fracture aperture and tilt angle on the stability of liquid bridges and the shape of a front during free gravity drainage process. Glass micromodels of two different aperture sizes were used to monitor the mechanism of gravity drainage of air-crude oil system, rotating around a bottom corner to create different tilting angles. Oil content within the matrix blocks was determined as a function of time using a series of images obtained during the experiments, from which net drainage rate from the upper and lower matrix blocks is calculated. Liquid bridges are more frequent but less stable at... 

Asphaltene deposition in a reservoir severely reduces the effective permeability and results in a reduction in oil production. The main term in asphaltene deposition modeling in the porous media is pore surface deposition. Previous models do not describe the effects of different parameters (i.e., concentration, velocity, and temperature) on the pore surface deposition term. We report the results of a series of experiments carried out to study the effects of the above parameters on the surface deposition term using an accurate thermal method. Based on these data, a new expression for the surface deposition term has been developed and implemented in asphaltene deposition modeling. The... 

Gravity drainage is known to be one of the most effective methods for oil recovery in fractured reservoirs. In this study, both free fall and controlled gravity drainage processes were studied using a transparent fractured experimental model, followed by modelling using commercial CFD software. The governing equations were employed based on the Darcy and mass conservation laws and partial pressure formulation. Comprehensive examination was done on variables such as fluid saturation, velocity, and pressure distribution in the matrix and fracture, as well as fluid front level and production rate. Additionally, effects of the model parameters on the gravity drainage performance were... 

The prediction of flow behavior in porous media can provide useful insights into the mechanisms involved in CO2 sequestration, petroleum engineering and hydrology. The multi-phase flow is usually simulated by solving the governing equations over an efficient model. The geostatistical (or fine grid) models are rarely used for simulation purposes because they have too many cells. A common approach is to coarsen a fine gird realization by an upscaling method. Although upscaling can speed up the flow simulation, it neglects the fine scale heterogeneity. The heterogeneity loss reduces the accuracy of simulation results. In this paper, the relation between heterogeneity loss during upscaling and... 

An ensemble-based, sequential assimilation procedure is developed and successfully applied to estimate absolute and relative permeabilities jointly under multi-phase (oil, gas and water) flow condition in the porous media. Two-phase oil-water and gas-oil relative permeabilities are represented by power-law models, and Stone's Model II is used to calculate three-phase oil relative permeability. Prior absolute permeability field is also generated with isotropic Gaussian covariance. The proposed method is validated by a twin numerical setup with three different case studies, in which a synthetic 2D reservoir under multi-phase flow condition is considered. In the first case, there is... 

Creating hydraulically induced fractures in oil/gas reservoirs is one of the methods for Enhanced Oil Recovery (EOR) that has been applied extensively in petroleum industry in recent years. Despite its popularity, the design process of Hydraulic Fracture treatment is mostly empirical based on the previous experiences gained in the oil-rich formation. The reason lies in the complexities involved in the Hydraulic Fracture process including interacting effects of fluid(s) flowand solid deformations, injection of non-Newtonian fluids in the porous media, leak-off of the injected fluid into the formation, complex geometry of the induced fracture in the intact or naturally fractured rock,... 

The selection of interface boundary conditions between porous-medium and clear-fluid regions is very important for the wide range of engineering applications. In this paper, the difference between two common types of fluid flow interfacial conditions between clear fluid and porous medium is analyzed in detail. These two types of fluid flow interfacial condition are stress-jump and stress-continuity conditions. The effects of porosity on these types of interface condition are studied. The results are presented for different Reynolds numbers in the range 1–40, porosity equal to 0.4 and 0.8 and Darcy number Da=5×10-4. In this study, the Darcy–Brinkmann–Forchheimer model is used to model the... 

In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at several fixed flow rate conditions. The micromodels were initially saturated with heavy crude oil. The produced oil as a function of injected volume of solvents was measured using image analysis of the continuously provided pictures. In order to investigate the macroscopic behavior of the process in different media, several fractured, with constant width, and nonfractured five-spot micromodels were designed and used. The measured data have also been used for verifying and developing a simulation model that was later used for sensitivity analysis of some parameters that affect oil recovery....