A Concurrent Multi-Scale Modeling of Heterogeneous Nano-Structures

, M.Sc. Thesis Sharif University of Technology Jahanbakhshi, Farzaneh (Author) ; Khoei, Amir Reza (Supervisor)

Abstract

In line with the high computational cost of Molecular Dynamics resulting in restrictions in time and domain, and incompetency of Finite Element method to deal with problems like those consisting of inhomogeneities, where no distinctive constitutive law may be considered, the multi scale methods have extensively settled as an alternative in recent decades. In continuation of preceding studies in the presented research, a concurrent multi scale procedure is employed for coupling MD-FE methods applying Lagrange multiplier approach in order for energy to resemble in transient zone and calculating the stiffness matrix of FE mesh employing the atomic grid laid beneath in order to investigate the...

Intelligent and Sequential Reservoir Model Updating and Uncertainty Assessment during EOR Process

, Ph.D. Dissertation Sharif University of Technology Jahanbakhshi, Saman (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Bozorgmehry Boozarjomehry, Ramin (Supervisor)

Abstract

Hydrocarbon reservoir management and development as well as planning of enhanced oil recovery (EOR) processes are based on the reservoir dynamic model. Thus, successful implementation of EOR scenarios greatly depends on the quality of the dynamic model and accuracy of the associated parameters in order to correctly describe fluid flow through porous media. First, a dynamic model is constructed based on the prior knowledge. However, because of the various types of error during model building, the prior model is not so accurate and perfect. Accordingly, new observation data, such as production and 4D seismic data, are utilized to calibrate the prior model and characterize the reservoir under a...

Non-equilibrium model of gravity drainage in a single block

, Article Journal of Porous Media ; Vol. 16, issue. 6 , 2013 , p. 559-571 ; ISSN: 1091028X Jahanbakhshi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology

2013

Abstract

This work concerns with developing a non-equilibrium model of gravity drainage in a single block. The proposed model which considers both non-equilibrium effects of capillary pressure and relative permeabilities is used for prediction of oil recovery by gravity drainage from a single block. Close agreement observed between the model results and experimental data disclosed that the non-equilibrium assumption is completely reliable for modeling of gravity drainage. The results revealed that when the characteristic time of the saturation variation is comparable with the time required to establish capillary equilibrium, the non-equilibrium effects in gravity drainage must be considered. The...

Non-equilibrium model of three-phase flow in porous media in presence of capillary and gravity forces

, Article Journal of Hydrology ; Vol. 478, issue , November , 2013 , p. 119-131 ; ISSN: 00221694 Jahanbakhshi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology

2013

Abstract

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann's problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann's problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The results of this work might be helpful to better understanding the...

Non-equilibrium model of three-phase flow in porous media in presence of capillary and gravity forces

, Article Journal of Hydrology ; Volume 478 , 2013 , Pages 119-131 ; 00221694 (ISSN) Jahanbakhshi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology

2013

Abstract

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann's problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann's problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The results of this work might be helpful to better understanding the...

Non-equilibrium model of gravity drainage in a single block

, Article Journal of Porous Media ; Volume 16, Issue 6 , 2013 , Pages 559-571 ; 1091028X (ISSN) Jahanbakhshi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology

2013

Abstract

This work concerns with developing a non-equilibrium model of gravity drainage in a single block. The proposed model which considers both non-equilibrium effects of capillary pressure and relative permeabilities is used for prediction of oil recovery by gravity drainage from a single block. Close agreement observed between the model results and experimental data disclosed that the non-equilibrium assumption is completely reliable for modeling of gravity drainage. The results revealed that when the characteristic time of the saturation variation is comparable with the time required to establish capillary equilibrium, the non-equilibrium effects in gravity drainage must be considered. The...

Fabrication and characterization of maleic anhydride grafted polypropylene membranes with high antifouling properties

, Article Journal of Applied Polymer Science ; Volume 133, Issue 36 , 2016 ; 00218995 (ISSN) Jahanbakhshi, N ; Mousavi, S. A ; Farhadi, F ; Sharif University of Technology

John Wiley and Sons Inc 2016

Abstract

In this study, maleic anhydride grafted polypropylene microporous flat-sheet membranes were prepared via a thermally induced phase separation method with a mixture of dibutyl phthalate and dioctyl phthalate as a diluent. The effects of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated membranes were investigated. The hydrophilicity results of the membranes demonstrated that membrane modification reduced the water contact angle by about 45°, whereas the pure water flux was enhanced about four times. The antifouling behavior of the fabricated membranes was also investigated in a membrane bioreactor. The results show that the pure water...

Numerical Modeling of Pulse Tube Refrigerator and Study of Multi-Dimensional Effect

, M.Sc. Thesis Sharif University of Technology Jahanbakhshi, Reza (Author) ; Saeedi, Mohammad Hassan (Supervisor)

Abstract

Pulse Tube Refrigerator (PTR) has an exceptional feature among all similar refrigerators, because of its unique characteristics such as long lifetime, compact size and no moving parts in low temperature. Despite of all these advantages because of its low efficiency, many researchers are trying to optimize performance of this refrigerator. Most of these efforts are based on one-dimensional simulation of the system. In this thesis, a two-dimensional analysis is performed to study the nature of flow field in an Inertance Tube Pulse Tube Refrigerator (ITPTR). This analysis is based on a numerical modeling of an entire ITPTR. To reach this purpose the two-dimensional form of mass, momentum and...

Numerical modeling of pulse tube refrigerator and sensitivity analysis of simulation

, Article HVAC and R Research ; Volume 19, Issue 3 , 2013 , Pages 242-256 ; 10789669 (ISSN) Jahanbakhshi, R ; Saidi, M. H ; Ghahremani, A. R ; Sharif University of Technology

2013

Abstract

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....

Joint estimation of absolute and relative permeabilities using ensemble-based Kalman filter

, Article Journal of Natural Gas Science and Engineering ; Volume 26 , September , 2015 , Pages 1232-1245 ; 18755100 (ISSN) Jahanbakhshi, S ; Pishvaie, M. R ; Boozarjomehry, R. B ; Sharif University of Technology

Elsevier 2015

Abstract

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...

Characterization of three-phase flow in porous media using the ensemble Kalman filter

, Article Scientia Iranica ; Volume 24, Issue 3 , 2017 , Pages 1281-1301 ; 10263098 (ISSN) Jahanbakhshi, S ; Pishvaie, M. R ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology

Sharif University of Technology 2017

Abstract

In this study, the ensemble Kalman filter is used to characterize threephase flow in porous media through simultaneous estimation of three-phase relative permeabilities and capillary pressures from production data. Power-law models of relative permeability and capillary pressure curves are used and the associated unknown parameters are estimated by assimilating the measured historical data. The estimation procedure is demonstrated on a twin numerical setup with two different scenarios, in which a synthetic 2D reservoir under three-phase flow is considered. In the first scenario, all the endpoints are assumed to be known and only the shape factors are estimated during the assimilation...

Impact of initial ensembles on posterior distribution of ensemble-based assimilation methods

, Article Journal of Petroleum Science and Engineering ; Volume 171 , 2018 , Pages 82-98 ; 09204105 (ISSN) Jahanbakhshi, S ; Pishvaie, M. R ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology

Elsevier B.V 2018

Abstract

In this study, impact of initial ensembles on posterior distribution of ensemble-based assimilation methods is statistically analyzed. Along with, sampling performance as well as uncertainty quantification of these methods are compared in terms of their ability to accurately and consistently evaluate unknown reservoir model parameters and reservoir future performance. For this purpose, a synthetic test problem, which is a small but highly nonlinear reservoir model under two-phase flow, is utilized. Subsequently, different initial ensemble sets are considered and are updated through the assimilation process performed on the test problem using ensemble-based assimilation methods. Afterwards,...

A hybrid assimilation scheme for characterization of three-phase flow in porous media

, Article Inverse Problems in Science and Engineering ; Volume 27, Issue 9 , 2019 , Pages 1195-1220 ; 17415977 (ISSN) Jahanbakhshi, S ; Pishvaie, M. R ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology

Taylor and Francis Ltd 2019

Abstract

In this study, ensemble Kalman filter (EnKF) is first applied to estimate absolute and relative permeabilities jointly under three-phase flow condition in the porous media. By assimilating historical data, absolute permeability field is adjusted progressively towards its reference. However, assimilation process does not improve the estimation of all relative permeability parameters, and some of them are poorly estimated at the end of assimilation. To improve the estimation of the relative permeability curves, we propose a new hybrid approach in which the estimation process of the absolute and relative permeabilities is separated. In this approach, gridblock permeabilities are again estimated...

Joint estimation of facies boundaries and petrophysical properties in multi-facies channelized reservoirs through ensemble-based Kalman filter and level set parametrization

, Article Journal of Petroleum Science and Engineering ; Volume 167 , 2018 , Pages 752-773 ; 09204105 (ISSN) Jahanbakhshi, S ; Pishvaie, M. R ; Boozarjomehry, R. B ; Sharif University of Technology

Elsevier B.V 2018

Abstract

Ensemble-based assimilation methods are the most promising tools for dynamic characterization of reservoir models. However, because of inherent assumption of Gaussianity, these methods are not directly applicable to channelized reservoirs wherein the distribution of petrophysical properties is multimodal. Transformation of facies field to level set functions have been proposed to alleviate the problem of multimodality. Level set representation ensures that the estimated fields are facies realizations as well as no modification of the assimilation method is required. Moreover, due to the complexity of the history matching problem in the channelized reservoirs, most researchers conventionally...

Application of Artificial Intelligence for Screening of Improved Oil Recovery Methods

, M.Sc. Thesis Sharif University of Technology Rezaeian, Javad (Author) ; Jamshidi, Saeid (Supervisor) ; Jahanbakhshi, Saman (Co-Supervisor)

Abstract

To achieve the highest amount of FOPT during reservoir life and the most net present value, the parameters that are effective in the production of the field are adjusted to be the best performance. In order to achieve these conditions, the reservoir model and the surface will be checked integrated so that the optimal mode of each parameter is determined in interaction with other parameters, so the first integrated model of the reservoir and the surface and then optimizing the target functions of cumulative production and the net present value is performed using the genetic algorithm.Since the number of parameters of reservoir model and surface in the studied field in this study is high,...

A coupling atomistic-continuum approach for modeling mechanical behavior of nano-crystalline structures

, Article Computational Mechanics ; Volume 54, Issue 2 , August , 2014 , Pages 269-286 ; ISSN: 01787675 Khoei, A. R ; Aramoon, A ; Jahanbakhshi, F ; Dormohammadi, H ; Sharif University of Technology

2014

Abstract

In this article, a novel approach is presented for the concurrent coupling of continuum-atomistic model in the nano-mechanical behavior of atomic structures. The study is focused on the static concurrent multi-scale simulation, which is able to effectively capture the surface effects intrinsic in the molecular mechanics modeling. The Hamiltonian approach is applied to combine the continuum and molecular models with the same weight in the overlapping domain. A Lagrange-multiplier method is employed over the overlapping domain for coupling the continuum nodal displacement with the atomic lattice deformation. A multiple-step algorithm is developed to decouple the solution process in the atomic...

A concurrent multi-scale modeling for dynamic behavior of nano-crystalline structures

, Article Computational Materials Science ; Volume 79 , 2013 , Pages 841-856 ; 09270256 (ISSN) Khoei, A. R ; Aramoon, A ; Jahanbakhshi, F ; Dormohammadi, H ; Sharif University of Technology

2013

Abstract

In this paper, a new multi-scale technique is developed for concurrent coupling of atomistic-continuum domains in modeling nano-mechanical behavior of atomic structures. A Lagrange multiplier method is employed over an overlapping domain to coupling the continuum nodal velocities with atomic lattice velocities. The Hamiltonian method is applied to combine the continuum and molecular Hamiltonians with the same weight in the overlapping domain. The mass and stiffness matrices of the continuum domain are obtained using a linear bridging map of the atomic lattice displacement laid underneath the continuum grid to the element displacements. Numerical examples are performed by presenting the...

Construction of Suitable Polymeric Membrane by Thermal Induce Phase Separation (TIPS) for using in the Membrane Bioreactor (MBR)

, M.Sc. Thesis Sharif University of Technology Jahanbakhshi, Nader (Author) ; Farhadi, Fathollah (Supervisor) ; Mousavi, Abbas (Supervisor)

Abstract

In this study, the response surface methodology (RSM) based on the central composite design (CCD) were used to prepare a polypropylene grafted maleic anhydride (PP-g-MA) microporous flat sheet membrane via thermally induced phase separation (TIPS) method. Mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) were used as diluent. The effect of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated microporous membranes in a bioreactor (MBR) were investigated. Analysis of variance (ANOVA) was used to determine which variables and interactions between variables have a significant effect on our responses. The ANOVA revealed that the...

Performance analysis and optimization of high capacity pulse tube refrigerator

, Article Cryogenics ; Volume 51, Issue 4 , 2011 , Pages 173-179 ; 00112275 (ISSN) Ghahremani, A. R ; Saidi, M. H ; Jahanbakhshi, R ; Roshanghalb, F ; Sharif University of Technology

2011

Abstract

High capacity pulse tube refrigerator (HCPTR) is a new generation of cryocoolers tailored to provide more than 250 W of cooling power at cryogenic temperatures. The most important characteristics of HCPTR when compared to other types of pulse tube refrigerators are a powerful pressure wave generator, and an accurate design. In this paper the influence of geometrical and operating parameters on the performance of a double inlet pulse tube refrigerator (DIPTR) is studied. The model is validated with the existing experimental data. As a result of this optimization, a new configuration of HCPTR is proposed. This configuration provides 335 W at 80 K cold end temperature with a frequency of 50 Hz...

The Automatic Matching of the Static Model of the Reservoir during Geosteering Using LWD Data

, M.Sc. Thesis Sharif University of Technology Bagheri, Mohammad Navid (Author) ; Jamshidi, Saeed (Supervisor) ; Jahanbakhshi, Saman (Co-Supervisor)

Abstract

In many fields, due to the lack of thickness of the reservoir layer, vertical drilling cannot be used due to low wellbore efficiency, so to solve this problem, directional and horizontal drilling is used. During drilling of highly deviated wells, to increase the efficiency of directional drilling, it should be tried to keep the path of the well completely in the reservoir layer, so that the full capacity of this type of drilling is used and the efficiency of the well is increased. To achieve this goal, Geo-Steer drilling technology is proposed in which decisions on the path of the well are made with the help of current reservoir and geological data. In this type of drilling, instantaneous...