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gravity-drainage
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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 ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology
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...
The gas-oil gravity drainage model in a single matrix block: A new relationship between relative permeability and capillary pressure functions
, Article Journal of Porous Media ; Vol. 14, issue. 8 , 2011 , p. 709-720 ; ISSN: 1091028X ; Ghazanfari, M. H ; Kamyab, M ; Masihi, M ; Sharif University of Technology
Abstract
This work concerns modeling of gas-oil gravity drainage for a single block of naturally fractured reservoirs. The nonlinearity induced from saturation-dependant capillary pressure and relative permeability functions makes a gravity drainage model difficult to analytically and numerically solve. Relating the capillary pressure and relative permeability functions is a potential method to overcome this problem. However, no attempt has been made in this regard. In this study a generalized one-dimensional form of gas-oil gravity drainage model in a single matrix block, presented in the literature, is considered. In contrast with commonly used forms of capillary pressure and relative permeability...
A study of enhanced heavy oil recovery by two well cyclical steam assisted gravity drainage (TWC-SAGD) in conventional and fractured reservoirs
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 10 , Dec , 2014 , pp. 1065-1076 ; ISSN: 15567036 ; Bolouri, S. H ; Sharif University of Technology
Abstract
Steam-assisted gravity drainage is one of the most promising strategies to develop huge heavy oil and bitumen accumulations. Like the other thermal processes, this method aims at reducing oil viscosity by increasing the temperature. But in an economical point of view, it requires a great volume of steam for injection. Moreover, early breakthrough of steam and high steam-oil ratio makes it uneconomical, especially in long production time. In this study, a new method, two wells cyclical steam-assisted gravity drainage is compared with a conventional steam-assisted gravity drainage process. Well configuration in two wells cyclical steam-assisted gravity drainage is the same as the...
Investigating the role of ultrasonic wave on two-phase relative permeability in a free gravity drainage process
, Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 763-771 ; Karimi, R ; Najafi, I ; Ghazanfari, M. H ; Ghotbi, C ; Sharif University of Technology
Abstract
In this work, the process of free gravity drainage under the influence of ultrasonic waves was investigated. A glass bead pack porous medium was used to perform free fall gravity drainage experiments. The tests were performed in the presence and absence of ultrasonic waves, and the data of recovery were recorded versus time under both conditions. The wetting phase relative permeability curves were obtained using the data of recovery versus time, based on the Hagoort backward methodology. Subsequently, using the wetting phase relative permeability curve, the relative permeability of non-wetting phases were calculated by performing history matching to the experimental production data. The...
Estimation of naturally fractured oil reservoir properties using the material balance method
, Article Scientia Iranica ; Volume 21, Issue 3 , 2014 , Pages 781-791 ; ISSN: 10263098 ; Jamshidi, S ; Gholinezhad, S ; Sharif University of Technology
Abstract
In fractured reservoirs, a large variation of permeability due to the presence of fractures leads to changes in the production mechanism compared to conventional reservoirs. Hence, an appropriate model with the ability to describe the reservoir properly can provide a more confident prediction of its future performance. One of the features of a representative model is the number and height of the matrix blocks. The determination of these two parameters is one of the decisive steps in the calculation of an accurate amount of oil production from these reservoirs. In fact, matrix height shows its effect as a gravity force, which is one of the driving mechanisms. If the matrix height is less than...
Analytical modeling of oil production from a matrix block by free fall gravity drainage mechanism
, Article Energy Exploration and Exploitation ; Volume 31, Issue 6 , October , 2013 , Pages 821-832 ; 01445987 (ISSN) ; Ardakany, M ; Ghazanfari, M ; Sharif University of Technology
2013
Abstract
Free fall gravity drainage is the most effective mechanism in gas invaded zone of fractured reservoirs. Although several analytical models have been proposed to characterize this mechanism, most of them suffer from inadequate reality, such as neglecting capillary pressure. In this study, a new analytical model was proposed to predict the oil recovery versus time for a homogeneous matrix block under a free fall gravity drainage mechanism. Considering the effect of viscous, gravity as well as capillary forces, the model was developed. This model is applicable to different conditions of gravity and capillary force, as well as when both forces are active. Along with core scale experimental data...
Simulation of multiphase flows in porous media with gravitational effects using dominant wave method
, Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 23, Issue 7 , 2013 , Pages 1204-1224 ; 09615539 (ISSN) ; Manzari, M. T ; Hannani, S. K ; Rasouli, A ; Sharif University of Technology
2013
Abstract
Purpose - In this paper, the flow of multiphase fluids in a one-dimensional homogeneous porous media involving the gravity effects is numerically studied using the dominant wave method. The paper aims to discuss these issues. Design/methodology/approach - The numerical scheme used for solving the pressure equations, obtained for the black-oil model, is a backward Euler scheme while the hyperbolic mass conservation equations, derived for both black-oil and Buckley-Leverett models, are solved using the dominant wave method. Higher-order schemes are achieved using either variable derivatives along with the minmod limiter or a MUSCL type interface construction scheme using the Fromm's limiter....
Application of fast-SAGD in naturally fractured heavy oil reservoirs: A case study
, Article SPE Middle East Oil and Gas Show and Conference, MEOS, Proceedings, Manama ; Volume 3 , March , 2013 , Pages 1946-1953 ; 9781627482851 (ISBN) ; Hashemi Kiasari, H ; Alizadeh, N ; Mighani, S ; Kamari, A ; Baker Hughes ; Sharif University of Technology
2013
Abstract
Steam injection process has been considered for a long time as an effective method to exploit heavy oil resources. Over the last decades, Steam Assisted Gravity Drainage (SAGD) has been proved as one of the best steam injection methods for recovery of unconventional oil resources. Recently, Fast-SAGD, a modification of the SAGD process, makes use of additional single horizontal wells alongside the SAGD well pair to expand the steam chamber laterally. This method uses fewer wells and reduces the operational cost compared to a SAGD operation requiring paired parallel wells one above the other. The efficiency of this new method in naturally fractured reservoir is not well understood....
Experimental investigation of secondary and tertiary oil recovery from fractured porous media
, Article Journal of Petroleum Exploration and Production Technology ; Volume 3, Issue 3 , September , 2013 , Pages 179-188 ; 21900558 (ISSN) ; Ayatollahi, S ; Rahmanifard, H ; Jahanmiri, A ; Riazi, M ; Sharif University of Technology
2013
Abstract
Naturally fractured reservoirs (NFRs) contribute in large extent to oil and gas production to the ever increasing market demand of fossil energy. It is believed that the vertical displacement of oil during gas injection assisted by gravity drainage (GAGD) is one of the most efficient methods for oil recovery in these reservoirs. Hence, in this work, unconsolidated packed models of cylindrical geometry surrounded by fracture were utilized in order to perform a series of flow visualization experiments during which the contribution of different parameters such as the extent of matrix permeability, physical properties of oil (viscosity, density, and surface tension) and the withdrawal rate was...
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) ; 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...
An experimental investigation of the effect of fracture dip angle on oil recovery and drainage rate in free fall gravity drainage in fractured reservoirs using a glass micromodel (A pore level investigation)
, Article Petroleum Science and Technology ; Volume 31, Issue 4 , 2013 , Pages 355-367 ; 10916466 (ISSN) ; Kharrat, R ; Ghazanfari, M ; Sharif University of Technology
2013
Abstract
Gravity drainage is the main production mechanism in the gas invaded zone in naturally fractured reservoirs. However, there are large ambiguities and complexities, resulting from the dynamic of oil depletion from matrix blocks toward the fracture network. Visualization of drained oil at pore scale using glass micromodels provides the opportunity to better understand the effects of different parameters which might affect oil recovery from fractured reservoirs. In this work a micromodel apparatus generated by laser etching is used to perform some gravity drainage tests on the network patterns. The experiments were performed on double block systems using crude oil. The block to block...
The effect of geometrical properties of reservoir shale barriers on the performance of Steam-assisted Gravity Drainage (SAGD)
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 34, Issue 23 , 2012 , Pages 2178-2191 ; 15567036 (ISSN) ; Sharif University of Technology
Abstract
Many bitumen reservoirs contain shale layers of varying thickness, lateral extent, and frequency. These shale layers, depending on their size, vertical and horizontal locations, and continuity throughout the reservoir, may act as a flow barrier and severely reduce vertical permeability of the pay zone and slow down the steam-assisted gravity drainage steam chamber development. Therefore, to improve productivity in these reservoirs, understanding of the effects of reservoir heterogeneities has become necessary. This work presents numerical investigation of the effects of shale barriers on steam-assisted gravity drainage performance when applied to produce mobile heavy oil. The most concern of...
An experimental investigation of fracture tilt angle effects on frequency and stability of liquid bridges in fractured porous media
, Article Petroleum Science and Technology ; Volume 30, Issue 8 , Mar , 2012 , Pages 807-816 ; 10916466 (ISSN) ; Kharrat, R ; Ghazanfari, M. H ; Dejam, M ; Sharif University of Technology
Abstract
Liquid bridges are believed to play an important role in improving the recovery of fractured reservoirs. However, little is known about the stability of liquid bridges in fractured media at the pore scale. In this work, a glass micromodel representing a stack of two blocks was used at different tilt angles to monitor the frequency and stability of liquid bridges formed during free-fall gravity drainage as a function of tilt angle. It was observed that by increasing the tilt angle, the liquid bridge frequency decreased but its stability increased. This resulted in higher ultimate recovery. In addition, it was found that during the first half of the experiments, the number of bridges was...
Investigation of the effect of geometrical properties of networked fractures on the efficiency of steam-assisted gravity drainage process
, Article Petroleum Science and Technology ; Volume 29, Issue 16 , Jul , 2011 , Pages 1625-1636 ; 10916466 (ISSN) ; Kharrat, R ; Vossoughi, S ; Sharif University of Technology
2011
Abstract
Various fracture geometrical properties such as orientation, extension, discontinuity, dispersion, location, and networking were investigated. Results indicate improved oil recovery and sweep efficiency in the presence of vertical fractures. Longer vertical fractures seemed to have even more beneficial effects. Horizontal fractures revealed detrimental effects on oil recovery and the performance became worse for longer horizontal fractures. Discontinuous horizontal fractures caused a better performance especially when combined with continuous vertical fractures (networking). Vertical fractures helped the growth of the steam chamber in the vertical direction, which resulted in higher oil...
The gas-oil gravity drainage model in a single matrix block: A new relationship between relative permeability and capillary pressure functions
, Article Journal of Porous Media ; Volume 14, Issue 8 , 2011 , Pages 709-720 ; 1091028X (ISSN) ; Ghazanfari, M. H ; Kamyab, M ; Masihi, M ; Sharif University of Technology
2011
Abstract
This work concerns modeling of gas-oil gravity drainage for a single block of naturally fractured reservoirs. The nonlinearity induced from saturation-dependant capillary pressure and relative permeability functions makes a gravity drainage model difficult to analytically and numerically solve. Relating the capillary pressure and relative permeability functions is a potential method to overcome this problem. However, no attempt has been made in this regard. In this study a generalized one-dimensional form of gas-oil gravity drainage model in a single matrix block, presented in the literature, is considered. In contrast with commonly used forms of capillary pressure and relative permeability...
Factors affecting the gravity drainage mechanism from a single matrix block in naturally fractured reservoirs
, Article Special Topics and Reviews in Porous Media ; Volume 2, Issue 2 , 2011 , Pages 115-124 ; 21514798 (ISSN) ; Ghazanfari, M. H ; Mashayekhizadeh, V ; Kamyab, M ; Sharif University of Technology
2011
Abstract
Despite numerous experimental and numerical studies, fundamental understanding of how the matrix block height, the density difference between petroleum and gas, and matrix capillary pressure could affect the oil recovery from a single matrix block in naturally fractured reservoirs remains a topic of debate in the literature. In this work a one-dimensional gravity drainage model developed by Firoozabadi and Ishimoto (1994) is considered and numerically solved. The Fourier series method is applied for a numerical Laplace inversion of the dimensionless mathematical model; this type of inversion method has rarely been used in petroleum applications. The obtained results revealed that by...
Pore-Level Observation of Free Gravity Drainage of Oil in Fractured Porous Media
, Article Transport in Porous Media ; Volume 87, Issue 2 , 2011 , Pages 561-584 ; 01693913 (ISSN) ; Ghazanfari, M. H ; Kharrat, R ; Dejam, M ; Sharif University of Technology
2011
Abstract
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...
A mathematical and experimental analysis of role of ultrasonic wave radiation on relative permeabilties in gravity drain
, Article 73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 ; Volume 7 , May , 2011 , Pages 5104-5108 ; 9781617829666 (ISBN) ; Keshavarzi, B ; Ghazanfari, M ; Ghotbi, C ; Amani, M ; Sharif University of Technology
Society of Petroleum Engineers
2011
Abstract
This work concerns with experimental and analytical investigation of role of ultrasonic wave radiation in relative permeability of both wetting and non-wetting phases in a free gravity drainage process in porous media under the influence of ultrasonic wave. Glass beads ranged from 70 to 100 mesh sizes were packed and used in the tests. The working fluids consist of distilled water, kerosene and Doroud and Paidar crude oils as wetting and air as non-wetting phase. The measured oil recovery data along with Hagoort (1984) backward methodology were used to determine and to compare the relative permeability of wetting phases in presence and absence of ultrasonic radiation. In addition, the...
Free fall and controlled gravity drainage processes in fractured porous media: Laboratory and modelling investigation
, Article Canadian Journal of Chemical Engineering ; Volume 93, Issue 12 , October , 2015 , Pages 2286-2297 ; 00084034 (ISSN) ; Ayatollahi, S ; Masihi, M ; Sharif University of Technology
Wiley-Liss Inc
2015
Abstract
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...
Study and Development of Dual Porosity/Permeability Models for Simulation of Forced Gravity Drainage Mechanism in Fractured Porous Media
, M.Sc. Thesis Sharif University of Technology ; Massihi, Mohsen (Supervisor) ; Gerami, Shahab (Supervisor) ; Ganjeh Ghazvini, Mostafa (Co-Advisor)
Abstract
The available investigations show that gravity drainage mechanism in fractured reservoir make a high recovery factor in comparison with other mechanisms. In recent years, the forced gravity drainage assisted by gas injection is also introduced; despite of its importance there is no comprehensive modeling study in the literature. The fractured reservoir is simulated frequently by dual porosity models in which the transfer function is the key issue for this method of simulation. This study makes an effort by comparison of different transfer functions with fine grid simulation results of a single block model, in order to evaluate their ability for simulation of forced gravity drainage...