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M. Jamiolahmady - One of the best experts on this subject based on the ideXlab platform.
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Optimization of hydraulic fracture geometry in gas condensate reservoirs
Fuel, 2014Co-Authors: Hojjat Mahdiyar, M. JamiolahmadyAbstract:Abstract An optimized design for hydraulic fracturing is of great importance especially with the growing demand for this method as a means of production enhancement from unconventional gas reservoirs. The first Optimum Fracture Design (OFD) approach, which maximizes well productivity for a given fracture volume, was introduced by Prats in 1960 for single-phase Darcy flow systems. This was then further developed and presented in the form of Unified Fractured Design (UFD) charts by Valko et al. (1998), which is applicable to Pseudo-steady state conditions. Later on, some methodologies have been proposed to make UFD applicable to gas condensate systems assuming the distribution of the condensate phase around the fracture as a rectangular damage zone with constant thickness and reduced permeability. These latter methods are generally oversimplified as they neglect different possible shapes of the two phase region around the fracture and the variation of relative permeability with interfacial tension (IFT) and velocity for these low IFT systems. They also require data that are not readily available, in particular the pressure profile (required to identify the two-phase boundary) around the Wellbore. In this paper, we introduce an explicit formulation and a more general methodology for OFD that is applicable to both Steady state and Pseudo-steady state single-phase gas and two-phase gas condensate flow systems and includes the important flow parameters in both the matrix and fracture. The optimum fracture dimensions are obtained by maximizing the Effective Wellbore Radius, using the recently developed correlation by Mahdiyar et al. (2011). This formulation accounts for the mechanical and flow skins based on quite readily available information at Wellbore conditions. The integrity of the introduced formulation has been verified for many different prevailing conditions, whilst highlighting the errors of using conventional approaches with some important practical guidelines. In this exercise, the maximum productivity calculated using the proposed formulation is compared with results of the literature or our in-house simulator. This program, using a fine grid approach, simulates gas condensate flow around a hydraulically fractured well for various fracture length–width ratios and identifies the optimum fracture dimensions, for a given fracture volume, providing maximum mass flow rate.
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A new, accurate and simple model for calculation of productivity of deviated and highly deviated well – Part I: Single-phase incompressible and compressible fluid
Fuel, 2012Co-Authors: Panteha Ghahri, M. JamiolahmadyAbstract:Abstract Nowadays in the oil and gas industry, many deviated ( 30 ⩽ θ ⩽ 60 ), and highly deviated ( 60 ⩽ θ 90 ) wells are drilled to increase Wellbore exposure of the reservoir and improve the productivity. A few correlations have been developed for productivity calculation of such wells but are only applicable to single-phase Darcy flow conditions with their extension to anisotropic formations. So far, however, no model/correlation has been proposed to predict the productivity of these wells for non-Darcy (inertia) flow conditions. Currently, for such well productivity calculations, a commercial numerical reservoir simulator is required to simulate the three-dimensional flow geometry, using a fine grid approach, which is impractical, costly and cumbersome. In this study, a three-dimensional mathematical simulator has been developed to investigate the single-phase flow behaviours around a deviated well. A large data bank of well productivity was generated, covering a wide range of variations of pertinent parameters, including the well length and angle, Wellbore Radius, reservoir dimensions, anisotropy, fluid properties and velocity. Using the results from the in-house simulator result, based on these results, the approach recently proposed for predicting horizontal well productivity [11] was extended to develop a general method, which can be applied to both horizontal and deviated wells placed in isotropic or anisotropic formations and flowing under either Darcy or non-Darcy flow conditions. In this method, the complex flow behaviour around the three-dimensional (3-D) deviated/horizontal wells is replicated by an equivalent open hole. The impact of pertinent parameters is quantified in terms of a skin or, in another form, an Effective Wellbore Radius of the equivalent open hole. This new correlation is easy to use, no numerical simulator is needed and a quite simple spreadsheet can be used to provide an accurate estimation of the horizontal/deviated well productivity in gas and oil reservoirs.
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Gas Condensate Flow Around Hydraulically Fractured Wells
Transport in Porous Media, 2011Co-Authors: H. Mahdiyar, M. Jamiolahmady, M. SohrabiAbstract:Fracturing is one of the most common well-stimulation techniques especially for tight gas-condensate reservoirs. Considerable efforts have been devoted to this subject albeit mainly for single-phase or conventional gas oil systems. Gas condensate flow around hydraulically fractured wells (HFWs) is different from that in conventional gas oil systems. Previous studies (Danesh et al. in Gas Condensate Recovery Studies, 1994 ; Jamiolahmady in Transp Porous Media 41(1): 17–46, 2000 ) have shown that at low to moderate velocities, the relative permeability of these low interfacial tension systems increases as velocity increases and/or interfacial tension decreases. At very high velocity values, on the other hand, the inertial effect becomes dominant, reducing the relative permeability as velocity increases (Forchheimer in Hydraulik, Chap 15, Teubner, Leipzik, 1914 ). Description of HFWs in gas condensate reservoirs using the existing reservoir simulators requires the use of very fine grids to capture the abrupt changes in flow and rock parameters for these systems. This task is very cumbersome, time consuming and impractical. In this work, a two-dimensional mathematical simulator has been developed, based on finite-difference methods. The simulator accounts for phase change, condensate drop out, coupling and inertial effects. This single-well model has been used to investigate the impact of important geometrical and flow parameters on the performance of a HFW. Based on this investigation new formulae have been developed for fracture skin factor and Effective Wellbore Radius. The developed formula for Effective Wellbore Radius, which is applicable under both steady state and pseudo-steady state conditions, can be used in an equivalent open-hole system replicating flow around HFWs. The approach is similar to that followed for single phase systems albeit with a modified formula for the fracture conductivity term as developed here. Another important application of these formulae is in the optimization of fracture dimensions for a given fracture volume, in gas condensate reservoirs.
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A new method for productivity calculation of perforated wells in Gas condensate reservoirs
Journal of Petroleum Science and Engineering, 2011Co-Authors: M. Jamiolahmady, Hojjat Mahdiyar, Panteha Ghahri, M. SohrabiAbstract:Abstract Flow in perforated regions has been the subject of numerous investigations in the past 60 years. These studies have mainly concentrated on proposing practical tools for the productivity estimation of perforated wells. The skin factor proposed can be applied in an equivalent (one dimensional radial) open-hole system replicating the flow around the actual complex three dimensional flow geometry of the perforated region. However, the majority of these studies concentrate on single-phase flow conditions. In gas condensate systems at relatively low interfacial tension (IFT) values, phase change and dependency of relative permeability on velocity and interfacial tension add significant complexity to proposing such an efficient and much needed tool for practical applications. This work is aimed at the development of a practical and convenient method for defining an Effective Wellbore Radius of an equivalent open-hole system, replicating flow around a perforated well in gas condensate reservoirs. The new method is based on the physics of the flow and applicable for both single-phase non-Darcy and two-phase gas condensate flow systems. Since the mechanical perforation skin formulations available in the literature are not accurate for highly anisotropic formations, a new more efficient skin formulation is introduced for such applications. In these exercises the finite-element based simulator developed by Jamiolahmady et al. (2007) was used to generate the large bank of data required to confirm the integrity of the proposed practical approach for productivity calculation of perforated wells in gas condensate reservoirs.
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Improved Darcy and non-Darcy flow formulations around hydraulically fractured wells
Journal of Petroleum Science and Engineering, 2011Co-Authors: Hojjat Mahdiyar, M. Jamiolahmady, M. SohrabiAbstract:Abstract Fracturing is one of the most common well stimulation techniques especially for tight gas reservoirs. Hence, considerable amount of efforts have been devoted to study the performance of hydraulically fractured wells (HFWs). However, there are uncertainties regarding the impact of some of the pertinent parameters, especially the non-Darcy effect. In this work, a number of simulators have been developed to study and compare the productivity of a HFW at both steady and pseudo steady states conditions. Description of HFWs in gas reservoirs using such numerical simulators requires the use of very fine grids to capture the significant changes of flow properties occurring in and around the fracture. This task is very cumbersome, time consuming and impractical. Therefore, the results of the in-house simulators have been used to develop more generalized formulae for calculation of Darcy flow fracture skin and Effective Wellbore Radius. These formulae can be used in an equivalent open-hole system that replicates flow around HFW with no need for the fine grid exercise. Considering that inertial effect can significantly reduce the Effective fracture conductivity, we have extended the application of these developed formulae to non-Darcy flow systems by replacing absolute fracture conductivity with the Effective fracture conductivity. Here we have also addressed the conflicting reports on the extent of negative impact of inertia on the flow performance of HFWs and have identified the most reliable formula.
Panteha Ghahri - One of the best experts on this subject based on the ideXlab platform.
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A new and simple model for the prediction of horizontal well productivity in gas condensate reservoirs
Fuel, 2018Co-Authors: Panteha Ghahri, Mahmoud Jamiolahmadi, Ebrahim Alatefi, David Wilkinson, Farzaneh Sedighi Dehkordi, Hossein HamidiAbstract:Abstract Horizontal well drilling is a well-established technology to enhance well productivity by increasing reservoir contact compared to that of vertical wells under the same conditions. In gas condensate reservoirs, in addition to the three-dimensional (3D) nature of the flow geometry around the horizontal well, the flow behaviour is further complicated by the phase change and the variation of relative permeability (kr) due to the coupling (increase in kr by an increase in velocity or decrease in IFT) and inertia (a decrease in kr by an increase in velocity) effects. There are no practically attractive simple methods for well productivity calculations that account for these effects. Therefore, as an alternative, numerical simulation of such a complex 3D flow using commercial numerical simulators is usually adopted. This approach requires a 3D fine grid compositional approach which is very demanding, cumbersome and often associated with convergence problems due to numerical instability. Consequently, the introduction of a quick and reliable tool for long term well productivity calculations for gas-condensate systems is the main objective of the present work. An in-house simulator was developed to realistically simulate the multiphase flow of gas and condensate around horizontal wells. Using this model, a large data bank was then generated covering the impact of a wide range of pertinent geometric and flow parameters on well performance including: well and reservoir geometries, reservoir and bottom-hole pressure, fluid velocity, gas oil ratio and fluid composition. Based on the results of these simulations, a new method has been proposed to predict the productivity of horizontal wells for gas and condensate systems. In this approach, the flow behaviour of gas and condensate around the well is quantified in terms of the Effective Wellbore Radius of an equivalent open hole that replicates flow around the actual 3D system. The Effective Wellbore Radius varies with fluid properties, velocity and interfacial tension (IFT), reservoir and Wellbore conditions. The integrity of the new methodology has also been verified for various fluids and flow conditions. This approach, included in a simple spreadsheet, can predict the horizontal well performance, significantly facilitating engineering and management decisions on the application of costly horizontal well technology.
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A new, accurate and simple model for calculation of productivity of deviated and highly deviated well – Part I: Single-phase incompressible and compressible fluid
Fuel, 2012Co-Authors: Panteha Ghahri, M. JamiolahmadyAbstract:Abstract Nowadays in the oil and gas industry, many deviated ( 30 ⩽ θ ⩽ 60 ), and highly deviated ( 60 ⩽ θ 90 ) wells are drilled to increase Wellbore exposure of the reservoir and improve the productivity. A few correlations have been developed for productivity calculation of such wells but are only applicable to single-phase Darcy flow conditions with their extension to anisotropic formations. So far, however, no model/correlation has been proposed to predict the productivity of these wells for non-Darcy (inertia) flow conditions. Currently, for such well productivity calculations, a commercial numerical reservoir simulator is required to simulate the three-dimensional flow geometry, using a fine grid approach, which is impractical, costly and cumbersome. In this study, a three-dimensional mathematical simulator has been developed to investigate the single-phase flow behaviours around a deviated well. A large data bank of well productivity was generated, covering a wide range of variations of pertinent parameters, including the well length and angle, Wellbore Radius, reservoir dimensions, anisotropy, fluid properties and velocity. Using the results from the in-house simulator result, based on these results, the approach recently proposed for predicting horizontal well productivity [11] was extended to develop a general method, which can be applied to both horizontal and deviated wells placed in isotropic or anisotropic formations and flowing under either Darcy or non-Darcy flow conditions. In this method, the complex flow behaviour around the three-dimensional (3-D) deviated/horizontal wells is replicated by an equivalent open hole. The impact of pertinent parameters is quantified in terms of a skin or, in another form, an Effective Wellbore Radius of the equivalent open hole. This new correlation is easy to use, no numerical simulator is needed and a quite simple spreadsheet can be used to provide an accurate estimation of the horizontal/deviated well productivity in gas and oil reservoirs.
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A new method for productivity calculation of perforated wells in Gas condensate reservoirs
Journal of Petroleum Science and Engineering, 2011Co-Authors: M. Jamiolahmady, Hojjat Mahdiyar, Panteha Ghahri, M. SohrabiAbstract:Abstract Flow in perforated regions has been the subject of numerous investigations in the past 60 years. These studies have mainly concentrated on proposing practical tools for the productivity estimation of perforated wells. The skin factor proposed can be applied in an equivalent (one dimensional radial) open-hole system replicating the flow around the actual complex three dimensional flow geometry of the perforated region. However, the majority of these studies concentrate on single-phase flow conditions. In gas condensate systems at relatively low interfacial tension (IFT) values, phase change and dependency of relative permeability on velocity and interfacial tension add significant complexity to proposing such an efficient and much needed tool for practical applications. This work is aimed at the development of a practical and convenient method for defining an Effective Wellbore Radius of an equivalent open-hole system, replicating flow around a perforated well in gas condensate reservoirs. The new method is based on the physics of the flow and applicable for both single-phase non-Darcy and two-phase gas condensate flow systems. Since the mechanical perforation skin formulations available in the literature are not accurate for highly anisotropic formations, a new more efficient skin formulation is introduced for such applications. In these exercises the finite-element based simulator developed by Jamiolahmady et al. (2007) was used to generate the large bank of data required to confirm the integrity of the proposed practical approach for productivity calculation of perforated wells in gas condensate reservoirs.
Dong Dong Gui - One of the best experts on this subject based on the ideXlab platform.
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Similar Structure of Solution for Effective Wellbore Radius Model in the Spherical-Shaped Matrix of Dual-Porosity Reservoir
Advanced Materials Research, 2013Co-Authors: Yong Wang, Fu Rong Wang, Dong Dong GuiAbstract:On the basis of percolation mechanism for dual-porosity, an Effective Wellbore Radius model in the dual-porosity was established, and the Laplace space solution could be obtained by solving this model. The solution had a similar structure and could be simplified into a unified expression in the different outer boundary conditions. The solution with a similar structure can avoid the complex calculations, it is beneficial to analyze the influence of various parameters on the solution in the dual-porosity model, and facilitate to master and use by engineering technicians.
Li Quan-yong - One of the best experts on this subject based on the ideXlab platform.
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The Seepage Problem in Dual-permeability Media Reservoir Based on Similar Structure of Solution
Journal of Xihua University, 2011Co-Authors: Li Quan-yongAbstract:Aiming at dual-permeability media reservoir,a model for non-linear seepage of dual-porosity media reservoir was established in this paper.In the model,the Effective Wellbore Radius and well bore storage is taken into consideration in the case of variable flow rate.By using Laplace transform,the nondimensional expressions of reservoir pressure and bottom hole pressure are obtained in Laplace space.And it is found that there is a similar structure among the expressions of solution under different outer boundaries.
Hossein Hamidi - One of the best experts on this subject based on the ideXlab platform.
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A new and simple model for the prediction of horizontal well productivity in gas condensate reservoirs
Fuel, 2018Co-Authors: Panteha Ghahri, Mahmoud Jamiolahmadi, Ebrahim Alatefi, David Wilkinson, Farzaneh Sedighi Dehkordi, Hossein HamidiAbstract:Abstract Horizontal well drilling is a well-established technology to enhance well productivity by increasing reservoir contact compared to that of vertical wells under the same conditions. In gas condensate reservoirs, in addition to the three-dimensional (3D) nature of the flow geometry around the horizontal well, the flow behaviour is further complicated by the phase change and the variation of relative permeability (kr) due to the coupling (increase in kr by an increase in velocity or decrease in IFT) and inertia (a decrease in kr by an increase in velocity) effects. There are no practically attractive simple methods for well productivity calculations that account for these effects. Therefore, as an alternative, numerical simulation of such a complex 3D flow using commercial numerical simulators is usually adopted. This approach requires a 3D fine grid compositional approach which is very demanding, cumbersome and often associated with convergence problems due to numerical instability. Consequently, the introduction of a quick and reliable tool for long term well productivity calculations for gas-condensate systems is the main objective of the present work. An in-house simulator was developed to realistically simulate the multiphase flow of gas and condensate around horizontal wells. Using this model, a large data bank was then generated covering the impact of a wide range of pertinent geometric and flow parameters on well performance including: well and reservoir geometries, reservoir and bottom-hole pressure, fluid velocity, gas oil ratio and fluid composition. Based on the results of these simulations, a new method has been proposed to predict the productivity of horizontal wells for gas and condensate systems. In this approach, the flow behaviour of gas and condensate around the well is quantified in terms of the Effective Wellbore Radius of an equivalent open hole that replicates flow around the actual 3D system. The Effective Wellbore Radius varies with fluid properties, velocity and interfacial tension (IFT), reservoir and Wellbore conditions. The integrity of the new methodology has also been verified for various fluids and flow conditions. This approach, included in a simple spreadsheet, can predict the horizontal well performance, significantly facilitating engineering and management decisions on the application of costly horizontal well technology.
