Search for: effective-permeability
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    Analysis of Conductivity between Two Points (Wells) in 2D Conventional Reservoir Models with Percolation Structure

    , M.Sc. Thesis Sharif University of Technology Tavagh-Mohammadi, Behnam (Author) ; Massihi, Mohsen (Supervisor)
    The nature of fluid flow in hydrocarbon reservoirs is very complex because of the complicated sedimentary processes. Proper modeling of distribution of these heterogeneities is crucial, affecting all aspect of fluid flow. The conventional approach to investigating the impact of geological uncertainties on the prediction of reservoir performance is to build a detailed geological model using geophysical, geological and petrophysical data, upscale it and finally perform flow simulation. Because of uncertainties in the data, it is necessary to construct a number of possible geological models and then run flow simulations many times to get a reliable model. This approach is computationally very... 

    Percolation-based effective permeability estimation in real heterogeneous porous media

    , Article 15th European Conference on the Mathematics of Oil Recovery, 29 August 2016 through 1 September 2016 ; 2016 ; 9462821933 (ISBN); 9789462821934 (ISBN) Masihi, M ; Gago, P ; King, P ; DCSE; Schlumberger; Shell ; Sharif University of Technology
    European Association of Geoscientists and Engineers 
    It has long been understood that flow behavior in heterogeneous porous media is largely controlled by the continuity of permeability contrasts. With this in mind, we are looking in new methods for a fast estimation of the effective permeability which concentrates on the properties of the percolating cluster. From percolation concepts we use a threshold permeability value (Kth) by which the gridblocks with the highest permeability values connect two opposite side of the system in the direction of the flow. Those methods can be applied to heterogeneous media of a range of permeabilities distribution and various underlying structures. We use power law relations and weighted power averages that... 

    Modeling formation damage due to asphaltene deposition in the porous media

    , Article Energy and Fuels ; Volume 25, Issue 2 , February , 2011 , Pages 753-761 ; 08870624 (ISSN) Soulgani, B. S ; Tohidi, B ; Jamialahmadi, M ; Rashtchian, D ; Sharif University of Technology
    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... 

    Estimation of the Effective Permeability of Heterogeneous Porous Media by Using Percolation Concepts

    , Article Transport in Porous Media ; Volume 114, Issue 1 , 2016 , Pages 169-199 ; 01693913 (ISSN) Masihi, M ; Gago, P. A ; King, P. R ; Sharif University of Technology
    Springer Netherlands  2016
    In this paper we present new methods to estimate the effective permeability (keff) of heterogeneous porous media with a wide distribution of permeabilities and various underlying structures, using percolation concepts. We first set a threshold permeability (kth) on the permeability density function and use standard algorithms from percolation theory to check whether the high permeable grid blocks (i.e., those with permeability higher than kth) with occupied fraction of “p” first forms a cluster connecting two opposite sides of the system in the direction of the flow (high permeability flow pathway). Then we estimate the effective permeability of the heterogeneous porous media in different... 

    Analysis of wideband circularly polarized ferrite-loaded antenna based on unidirectional resonant modes

    , Article IEEE Transactions on Magnetics ; Volume 53, Issue 9 , 2017 ; 00189464 (ISSN) Mashhadi, M ; Rejaei, B ; Komjani, N ; Ghalibafan, J ; Sharif University of Technology
    We propose a wideband circularly polarized antenna that consists of a metallic patch and some parasitically coupled elements mounted on a grounded dielectric-ferrite substrate. The metallic patch is fed by a proximity-coupled feed line placed between the ferrite and the dielectric layers. The parasitically coupled elements are included to improve the impedance bandwidth of antenna and are excited through the metallic patch. The antenna utilizes the resonant modes of the structure, which rotate only in the clockwise or counter-clockwise direction. A semi-Analytical solution based on the magnetic wall approximation shows that the resonance frequencies of the clock-and counter-clockwise... 

    Ferrite-based wideband circularly polarized microstrip antenna design

    , Article ETRI Journal ; Volume 41, Issue 3 , 2019 , Pages 289-297 ; 12256463 (ISSN) Mashhadi, M ; Komjani, N ; Rejaei, B ; Ghalibafan, J ; Sharif University of Technology
    John Wiley and Sons Inc  2019
    In this paper, a wideband, circularly polarized patch antenna is proposed that leverages the unidirectional resonant modes of a circular patch mounted on top of a grounded dielectric-ferrite substrate. The proposed antenna is fed via the proximity coupling method and several parasitically coupled patches are placed on a dielectric superstrate to enhance the impedance bandwidth of the antenna. The resonant modes of the structure rotate only in the clockwise or counter clockwise directions. In the frequency range where the effective permeability of the ferrite layer is negative, the resonance frequencies of these modes differ significantly, which produces a large axial ratio (AR) bandwidth.... 

    Reservoir flow simulation using combined vorticity-based gridding and multi-scale upscaling

    , Article Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition 2007 ""Resources, Professionalism, Technology: Time to Deliver"", Jakarta, 30 October 2007 through 1 November 2007 ; Volume 2 , 2007 , Pages 927-946 ; 9781604238594 (ISBN) Mahani, H ; Ashjari, M. A ; Firoozabadi, B ; Sharif University of Technology
    Society of Petroleum Engineers (SPE)  2007
    A novel technique for upscaling of detailed geological reservoir descriptions is presented. The technique aims at reducing both numerical dispersion and homogenization error, generated due to incorporating a coarse computational grid and assigning effective permeability to coarse grid blocks respectively. In particular we consider implicit-pressure explicit-saturation (IMPES) scheme where homogenization error impacts the accuracy of the coarse grid solution of the pressure equation. To reduce the homogenization error, we employ the new vorticity-based gridding that generates a non-uniform coarse grid with high resolution at high vorticity zones. In addition, to control numerical dispersion,... 

    High-quality integrated inductors based on multilayered meta-conductors

    , Article IEEE Microwave and Wireless Components Letters ; Volume 22, Issue 7 , 2012 , Pages 345-347 ; 15311309 (ISSN) Iramnaaz, I ; Schellevis, H ; Rejaei, B ; Fitch, R ; Zhuang, Y ; Sharif University of Technology
    We demonstrate high-quality integrated inductors built from a multilayer of alternating copper and ferromagnetic films. The multilayer acts as a meta-conductor whose effective permeability becomes nearly zero at its ferromagnetic anti-resonance frequency. This leads to a suppression of the skin effect and a significant increase in the quality factor of the device. Experiments show an up to 86% increase in quality factor compared to conventional copper-based spiral inductors at high frequencies  

    Utilization of percolation approach to evaluate reservoir connectivity and effective permeability: A case study on North Pars gas field

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1391-1396 ; 10263098 (ISSN) Sadeghnejad, S ; Masihi, M ; Pishvaie, M ; Shojaei, A ; King, P. R ; Sharif University of Technology
    Reservoir characterization, especially during early stages of reservoir life, is very uncertain, due to the scarcity of data. Reservoir connectivity and permeability evaluation is of great importance in reservoir characterization. The conventional approach to addressing this is computationally very expensive and time consuming. Therefore, there is a great incentive to produce much simpler alternative methods. In this paper, we use a statistical approach called the percolation theory, which considers a hypothesis wherein the reservoir can be split into either permeable (i.e. sand/fracture) or impermeable flow units (i.e. shale/matrix), and assumes that the connectivity of permeability... 

    A novel analytical model for a circularly-polarized, ferrite-based slot antenna by solving an integral equation for the electric field on the circular slot

    , Article Waves in Random and Complex Media ; 19 June , 2020 Heydari, M. B ; Ahmadvand, A ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    We propose and analyze a circularly polarized slot antenna built on a ferrite substrate which is saturated normal to its plane and metalized on both sides. The antenna is built by etching a circular slot in the top metal layer. The antenna operates in the frequency range where the effective permeability of ferrite is negative. An accurate analytical model is derived for the antenna by solving the integral equation for the electric field on the circular slot. The results obtained are in good agreement with numerical simulations. Using the analytical results, a practical antenna is designed that uses a microstrip feed line. For an antenna with inner and outer radii of 4.9 and 5.9 mm, the... 

    Static and dynamic evaluation of the effect of nanomaterials on the performance of a novel synthesized PPG for water shut-off and improved oil recovery in fractured reservoirs

    , Article Journal of Petroleum Science and Engineering ; Volume 189 , June , 2020 Khoshkar, P. A ; Fatemi, M ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier B. V  2020
    Among different methods which are introduced to reduce unwanted water production, “Preformed Particle Gel” (PPG) is a recently developed type of these gels that can have important advantages such as temperature resistance and long-term stability. The aim of the present work is to synthesize a new type of PPG in which the above specifications are improved even further with the advantage of the Nano-material (here after called N-PPG) and then investigate its effectiveness via static bulk tests as well as dynamic Hele-Shaw and Micromodel tests. In static tube tests, the swelling performance of N-PPG samples was evaluated under different conditions. The examined parameters include various pH of... 

    A reservoir conductivity evaluation using percolation theory

    , Article Petroleum Science and Technology ; Volume 29, Issue 10 , 2011 , Pages 1041-1053 ; 10916466 (ISSN) Sadeghnejad, S ; Masihi, M ; King, P. R ; Shojaei, A ; Pishvaie, M ; Sharif University of Technology
    Oil reservoirs are very complex with geological heterogeneities that appear on all scales. Proper modeling of the spatial distribution of these heterogeneities is crucial, affecting all aspects of flow and, consequently, the reservoir performance. Reservoir connectivity and conductivity evaluation is of great importance for decision-making on various possible development scenarios including infill drilling projects. This can be addressed by using the percolation theory approach. This statistical approach considers a hypothesis that the reservoir can be split into either permeable (good sands) or impermeable flow units (poor sands) and assumes that the continuity of permeability contrasts... 

    A multiple-point statistics algorithm for 3D pore space reconstruction from 2D images

    , Article Advances in Water Resources ; Volume 34, Issue 10 , October , 2011 , Pages 1256-1267 ; 03091708 (ISSN) Hajizadeh, A ; Safekordi, A ; Farhadpour, F. A ; Sharif University of Technology
    Fluid flow behavior in a porous medium is a function of the geometry and topology of its pore space. The construction of a three dimensional pore space model of a porous medium is therefore an important first step in characterizing the medium and predicting its flow properties. A stochastic technique for reconstruction of the 3D pore structure of unstructured random porous media from a 2D thin section training image is presented. The proposed technique relies on successive 2D multiple point statistics simulations coupled to a multi-scale conditioning data extraction procedure. The Single Normal Equation Simulation Algorithm (SNESIM), originally developed as a tool for reproduction of...