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Asaf Pekdeger - One of the best experts on this subject based on the ideXlab platform.
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Deep geothermal groundwater Flow in the Seferihisar–Balçova area, Turkey: results from transient numerical simulations of Coupled Fluid Flow and heat transport processes
Geofluids, 2010Co-Authors: Fabien Magri, Toygar Akar, Unsal Gemici, Asaf PekdegerAbstract:The Seferihisar–Balcova Geothermal system (SBG) is characterized by complex temperature and hydrochemical anomalies. Previous geophysical and hydrochemical investigations suggest that hydrothermal convection in the faulted areas of the SBG and recharge Flow from the Horst may be responsible for the observed patterns. A numerical model of Coupled Fluid Flow and heat transport processes has been built in order to study the possible Fluid dynamics of deep geothermal groundwater Flow in the SBG. The results support the hypothesis derived from interpreted data. The simulated scenarios provide a better understanding of the geophysical conditions under which the different Fluid dynamics develop. When recharge processes are weak, the convective patterns in the faults can expand to surrounding reservoir units or below the seafloor. These fault-induced drag forces can cause natural seawater intrusion. In the Melange of the Seferihisar Horst, the regional Flow is modified by buoyant-driven Flow focused in the series of vertical faults. As a result, the main groundwater divide can shift. Sealing caprocks prevent fault-induced cells from being overwhelmed by vigorous regional Flow. In this case, over-pressured, blind geothermal reservoirs form below the caprocks. Transient results showed that the front of rising hot waters in faults is unstable: the tip of the hydrothermal plumes can split and lead to periodical temperature oscillations. This phenomenon known as Taylor–Saffman fingering has been described in mid-ocean ridge hydrothermal systems. Our findings suggest that this type of thermal pulsing can also develop in active, faulted geothermal systems. To some extent, the role of an impervious fault core on the Flow patterns has been investigated. Although it is not possible to reproduce basin-scale transport processes, this first attempt to model deep groundwater geothermal Flow in the SBG qualitatively supported the interpreted data and described the different Fluid dynamics of the basin. GeoFluids (2010) 10, 388–405
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deep geothermal groundwater Flow in the seferihisar balcova area turkey results from transient numerical simulations of Coupled Fluid Flow and heat transport processes
Geofluids, 2010Co-Authors: Fabien Magri, Toygar Akar, Unsal Gemici, Asaf PekdegerAbstract:The Seferihisar–Balcova Geothermal system (SBG) is characterized by complex temperature and hydrochemical anomalies. Previous geophysical and hydrochemical investigations suggest that hydrothermal convection in the faulted areas of the SBG and recharge Flow from the Horst may be responsible for the observed patterns. A numerical model of Coupled Fluid Flow and heat transport processes has been built in order to study the possible Fluid dynamics of deep geothermal groundwater Flow in the SBG. The results support the hypothesis derived from interpreted data. The simulated scenarios provide a better understanding of the geophysical conditions under which the different Fluid dynamics develop. When recharge processes are weak, the convective patterns in the faults can expand to surrounding reservoir units or below the seafloor. These fault-induced drag forces can cause natural seawater intrusion. In the Melange of the Seferihisar Horst, the regional Flow is modified by buoyant-driven Flow focused in the series of vertical faults. As a result, the main groundwater divide can shift. Sealing caprocks prevent fault-induced cells from being overwhelmed by vigorous regional Flow. In this case, over-pressured, blind geothermal reservoirs form below the caprocks. Transient results showed that the front of rising hot waters in faults is unstable: the tip of the hydrothermal plumes can split and lead to periodical temperature oscillations. This phenomenon known as Taylor–Saffman fingering has been described in mid-ocean ridge hydrothermal systems. Our findings suggest that this type of thermal pulsing can also develop in active, faulted geothermal systems. To some extent, the role of an impervious fault core on the Flow patterns has been investigated. Although it is not possible to reproduce basin-scale transport processes, this first attempt to model deep groundwater geothermal Flow in the SBG qualitatively supported the interpreted data and described the different Fluid dynamics of the basin. GeoFluids (2010) 10, 388–405
Christopher Beaumont - One of the best experts on this subject based on the ideXlab platform.
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Coupled Fluid Flow and sediment deformation in margin-scale salt-tectonic systems: 1. Development and application of simple, single-lithology models
Tectonics, 2012Co-Authors: Sofie Gradmann, Christopher Beaumont, Steven J. IngsAbstract:[1] A methodology is presented to model Coupled Fluid Flow and deformation in rifted continental margin composite salt and siliciclastic tectonic systems; and we investigate their compaction and overpressuring behavior associated with continental margin-scale gravitational spreading. Compaction-driven Darcy Fluid Flow in clastic sediments is Coupled through the effective pressure to their frictional-plastic yielding and mechanical deformation. Viscous Flow of underlying salt is independent of Fluid pressure. Numerical models are adapted to the Oligo-Miocene phase of large-scale gravitational failure in the northwestern Gulf of Mexico, and represent the first study of this system that includes dynamically evolving Fluid pressure. Here we present the methodology and prototype models with single uniform sediment lithologies and simple parameterizations of their properties. The models serve to illustrate the interactions among compaction, generation of Fluid overpressure, and gravitational failure and spreading. Mechanical and viscous compaction behavior of sandstone-type and shale-type sediments are investigated. Results demonstrate that mechanical compaction can generate moderate overpressure in thick shale-type material, whereas high overpressure requires viscous compaction. In sandstone-type material, only viscous compaction can generate significant overpressure, though this requires tens of millions of years. Changes in the stress regime during gravitational-driven deformation enhance compaction and overpressure. Although illustrative of the methodology and basic processes, none of the prototype single-lithology models satisfactorily reproduces Oligo-Miocene Fluid pressure and deformational regimes of the Gulf of Mexico. Numerical models of layered sediments together with an improved formulation of viscous compaction, presented in part 2 of this set of companion papers, are more successful.
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Coupled Fluid Flow and sediment deformation in margin‐scale salt‐tectonic systems: 2. Layered sediment models and application to the northwestern Gulf of Mexico
Tectonics, 2012Co-Authors: Sofie Gradmann, Christopher BeaumontAbstract:[1] In paper 1 we described a methodology to model Coupled Fluid Flow and deformation in composite salt and siliciclastic tectonic systems and investigated their compaction and overpressuring behavior prior to and during continental margin-scale gravitational spreading. Compaction-driven Darcy Fluid Flow in clastic sediments is Coupled through the effective pressure to their frictional-plastic yield and mechanical deformation. Viscous Flow of the underlying salt is independent of Fluid pressure. Paper 1 presented prototype models that are limited to single uniform sediment lithologies, either sandstone-type or shale-type, that undergo mechanical and volumetric viscous compaction. In this paper we present models with layered sandstone-type and shale-type lithologies designed to better approximate the more complex stratigraphy of the Gulf of Mexico, our natural example. A first set of models demonstrates that layered lithologies can produce Fluid pressure regimes similar to those observed in sedimentary basins. We then introduce an improved formulation of viscous compaction that includes a stronger dependence on porosity and depth (used as proxy for temperature), thereby more effectively self-limiting viscous compaction. A second set of models with the improved viscous compaction formulation demonstrates that the onset of gravity spreading is mainly controlled by overpressuring in the landward end of the salt basin and that resulting shortening in the distal part is partly accommodated by horizontal compaction. Models with moderately high Fluid pressure best reproduce conditions considered to have been necessary for large-scale gravitational spreading in the northwestern Gulf of Mexico, which led to the formation of the Perdido Fold Belt.
Sofie Gradmann - One of the best experts on this subject based on the ideXlab platform.
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Coupled Fluid Flow and sediment deformation in margin-scale salt-tectonic systems: 1. Development and application of simple, single-lithology models
Tectonics, 2012Co-Authors: Sofie Gradmann, Christopher Beaumont, Steven J. IngsAbstract:[1] A methodology is presented to model Coupled Fluid Flow and deformation in rifted continental margin composite salt and siliciclastic tectonic systems; and we investigate their compaction and overpressuring behavior associated with continental margin-scale gravitational spreading. Compaction-driven Darcy Fluid Flow in clastic sediments is Coupled through the effective pressure to their frictional-plastic yielding and mechanical deformation. Viscous Flow of underlying salt is independent of Fluid pressure. Numerical models are adapted to the Oligo-Miocene phase of large-scale gravitational failure in the northwestern Gulf of Mexico, and represent the first study of this system that includes dynamically evolving Fluid pressure. Here we present the methodology and prototype models with single uniform sediment lithologies and simple parameterizations of their properties. The models serve to illustrate the interactions among compaction, generation of Fluid overpressure, and gravitational failure and spreading. Mechanical and viscous compaction behavior of sandstone-type and shale-type sediments are investigated. Results demonstrate that mechanical compaction can generate moderate overpressure in thick shale-type material, whereas high overpressure requires viscous compaction. In sandstone-type material, only viscous compaction can generate significant overpressure, though this requires tens of millions of years. Changes in the stress regime during gravitational-driven deformation enhance compaction and overpressure. Although illustrative of the methodology and basic processes, none of the prototype single-lithology models satisfactorily reproduces Oligo-Miocene Fluid pressure and deformational regimes of the Gulf of Mexico. Numerical models of layered sediments together with an improved formulation of viscous compaction, presented in part 2 of this set of companion papers, are more successful.
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Coupled Fluid Flow and sediment deformation in margin‐scale salt‐tectonic systems: 2. Layered sediment models and application to the northwestern Gulf of Mexico
Tectonics, 2012Co-Authors: Sofie Gradmann, Christopher BeaumontAbstract:[1] In paper 1 we described a methodology to model Coupled Fluid Flow and deformation in composite salt and siliciclastic tectonic systems and investigated their compaction and overpressuring behavior prior to and during continental margin-scale gravitational spreading. Compaction-driven Darcy Fluid Flow in clastic sediments is Coupled through the effective pressure to their frictional-plastic yield and mechanical deformation. Viscous Flow of the underlying salt is independent of Fluid pressure. Paper 1 presented prototype models that are limited to single uniform sediment lithologies, either sandstone-type or shale-type, that undergo mechanical and volumetric viscous compaction. In this paper we present models with layered sandstone-type and shale-type lithologies designed to better approximate the more complex stratigraphy of the Gulf of Mexico, our natural example. A first set of models demonstrates that layered lithologies can produce Fluid pressure regimes similar to those observed in sedimentary basins. We then introduce an improved formulation of viscous compaction that includes a stronger dependence on porosity and depth (used as proxy for temperature), thereby more effectively self-limiting viscous compaction. A second set of models with the improved viscous compaction formulation demonstrates that the onset of gravity spreading is mainly controlled by overpressuring in the landward end of the salt basin and that resulting shortening in the distal part is partly accommodated by horizontal compaction. Models with moderately high Fluid pressure best reproduce conditions considered to have been necessary for large-scale gravitational spreading in the northwestern Gulf of Mexico, which led to the formation of the Perdido Fold Belt.
Dongxiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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Coupled Fluid Flow and geomechanics for triple porosity dual permeability modeling of coalbed methane recovery
International Journal of Rock Mechanics and Mining Sciences, 2010Co-Authors: Zhijie Wei, Dongxiao ZhangAbstract:Abstract A Coupled Fluid-Flow and geomechanics model for simulating coalbed methane (CBM) recovery is presented. In the model, the Fluid-Flow process is simulated with a triple-porosity/dual-permeability model, and the coupling effects of effective stress and micro-pore swelling/shrinkage are modeled with the Coupled Fluid-Flow and geomechanical deformation approach. The mathematical model is implemented with a finite volume method. First, a case without considering coupling between Fluid-Flow and geomechanics is simulated and compared with an existing simulator. The effects of Coupled Fluid-Flow and geomechanics are then studied in detail with two illustrative examples. The first one is designed for testing the effective stress effect without micro-pore swelling/shrinkage effect, and the other for testing the coupling effects of the effective stress and micro-pore swelling/shrinkage on the methane production. The numerical results indicate that both the effective stress and the micro-pore shrinkage make a significant contribution to Fluid-Flow in CBM reservoir and to methane production. The methane production sensitivity to Young’s modulus and Langmuir sorption strain are investigated as well. Finally, we make a dynamic analysis of the coupling effects of Fluid-Flow process and geomechanics.
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Coupled Fluid Flow AND GEOMECHANICS IN COALBED METHANE RECOVERY STUDY
Modern Physics Letters B, 2010Co-Authors: Zhijie Wei, Dongxiao ZhangAbstract:In this paper, we present a Coupled Fluid Flow and geomechanics model for simulating coalbed methane recovery. In the model, the Fluid Flow process is simulated with a triple porosity/dual permeability representation, and the coupling effects of effective stress and matrix swelling/shrinkage approach are simulated with a Coupled Fluid Flow, geomechanics and gas adsorption/desorption model. The mathematical model is implemented with a fully implicit finite volume method and simulation is conducted to evaluate the effect of Coupled Fluid Flow, geomechanics, and gas adsorption/desorption.
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Data Assimilation of Coupled Fluid Flow and Geomechanics Using the Ensemble Kalman Filter
SPE Journal, 2010Co-Authors: Haibin Chang, Yan Chen, Dongxiao ZhangAbstract:Summary In reservoir history matching or data assimilation, dynamic data, such as production rates and pressures, are used to constrain reservoir models and to update model parameters. As such, even if under certain conceptualization the model parameters do not vary with time, the estimate of such parameters may change with the available observations and, thus, with time. In reality, the production process may lead to changes in both the Flow and geomechanics fields, which are dynamically Coupled. For example, the variations in the stress/strain field lead to changes in porosity and permeability of the reservoir and, hence, in the Flow field. In weak formations, such as the Lost Hills oil field, Fluid extraction may cause a large compaction to the reservoir rock and a significant subsidence at the land surface, resulting in huge economic losses and detrimental environmental consequences. The strong nonlinear coupling between reservoir Flow and geomechanics poses a challenge to constructing a reliable model for predicting oil recovery in such reservoirs. On the other hand, the subsidence and other geomechanics observations can provide additional insight into the nature of the reservoir rock and help constrain the reservoir model if used wisely. In this study, the ensemble-Kalman-filter (EnKF) approach is used to estimate reservoir Flow and material properties by jointly assimilating dynamic Flow and geomechanics observations. The resulting model can be used for managing and optimizing production operations and for mitigating the land subsidence. The use of surface displacement observations improves the match to both production and displacement data. Localization is used to facilitate the assimilation of a large amount of data and to mitigate the effect of spurious correlations resulting from small ensembles. Because the stress, strain, and displacement fields are updated together with the material properties in the EnKF, the issue of consistency at the analysis step of the EnKF is investigated. A 3D problem with reservoir Fluid-Flow and mechanical parameters close to those of the Lost Hills oil field is used to test the applicability.
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Coupled Fluid-Flow and geomechanics for triple-porosity/dual-permeability modeling of coalbed methane recovery
International Journal of Rock Mechanics and Mining Sciences, 2010Co-Authors: Zhijie Wei, Dongxiao ZhangAbstract:Abstract A Coupled Fluid-Flow and geomechanics model for simulating coalbed methane (CBM) recovery is presented. In the model, the Fluid-Flow process is simulated with a triple-porosity/dual-permeability model, and the coupling effects of effective stress and micro-pore swelling/shrinkage are modeled with the Coupled Fluid-Flow and geomechanical deformation approach. The mathematical model is implemented with a finite volume method. First, a case without considering coupling between Fluid-Flow and geomechanics is simulated and compared with an existing simulator. The effects of Coupled Fluid-Flow and geomechanics are then studied in detail with two illustrative examples. The first one is designed for testing the effective stress effect without micro-pore swelling/shrinkage effect, and the other for testing the coupling effects of the effective stress and micro-pore swelling/shrinkage on the methane production. The numerical results indicate that both the effective stress and the micro-pore shrinkage make a significant contribution to Fluid-Flow in CBM reservoir and to methane production. The methane production sensitivity to Young’s modulus and Langmuir sorption strain are investigated as well. Finally, we make a dynamic analysis of the coupling effects of Fluid-Flow process and geomechanics.
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Data Assimilation of Coupled Fluid Flow and Geomechanics via Ensemble Kalman Filter
All Days, 2009Co-Authors: Haibin Chang, Yan Chen, Dongxiao ZhangAbstract:Abstract In reservoir history matching or data assimilation, dynamic data such as production rates and pressures are used to constrain reservoir models and to update model parameters. As such, even if under certain conceptualization the model parameters do not vary with time, the estimate of such parameters may change with the available observations and thus with time. In reality, the production process may lead to changes in both the Flow and geomechanics fields, which are dynamically Coupled. For example, the variations in the stress/strain field lead to changes in porosity and permeability of the reservoir and hence in the Flow field. In weak formations such as the Lost Hills oilfield, Fluid extraction may cause a large compaction to the reservoir rock and a significant subsidence at the land surface, resulting in huge economic losses and detrimental environmental consequences. The strong nonlinear coupling between reservoir Flow and geomechanics possesses a challenge to construct a reliable model for predicting oil recovery in such reservoirs. On the other hand, the subsidence and other geomechanics observations can provide additional insight into the nature of the reservoir rock and help constrain the reservoir model if used wisely. In this study, the Ensemble Kalman filter (EnKF) approach is used to estimate reservoir Flow and material properties by jointly assimilating dynamic Flow and geomechanics observations. The resulting model can be used for managing and optimizing production operations and for mitigating the land subsidence. The use of surface displacement observations improves the match to both production and displacement data. Localization is used to facilitate the assimilation of a large amount of data and to mitigate the effect of spurious correlations resulting from small ensembles. Since the stress, strain, and displacement fields are updated together with the material properties in The EnKF, the issue of consistency at the analysis step of the EnKF is investigated. A 3D problem with reservoir Fluid-Flow and mechanical parameters close to those of the Lost Hills oilfield is used to test the applicability. Introduction The geomechanical behavior of a reservoir is usually only considered through rock compressibility in reservoir simulators. Rock compressibility determines the change of reservoir pore volume with respect to the change of pressure. The stress fields change, however, dramatically during depletion, water injection or different applications of enhanced oil recovery techniques. The changes in the stress field induce various geomechanical phenomena, such as land subsidence, abrupt compaction of the reservoir, induced fracturing, enhancement of natural fractures and fault activation. Among these phenomena, reservoir compaction and surface subsidence are most commonly seen. Well know examples include the sea floor subsidence in the Ekofisk field and Valhall field in the North Sea (Pattillo et al. 1998), subsidence in the Lost Hill field, California (Wallace and Pugh 1993) and in the region of the Boliva Coast and Lagunillas in Venezuela (van der Knapp and van der Vlis 1967). These complicated geomechanical situations require more sophisticated methods to take them into account in order to better predict the production and avoid facility failures. In the past ten years, extensive efforts have been made to couple the Fluid-Flow and geomechanics simulations to model the complex process during hydrocarbon production (Chin et al. 2000; Dean et al. 2006; Samier et al. 2006). Geomechanics module is available in several commercial reservoir simulators to facilitate the Coupled modeling of Fluid-Flow and geomechanical processes.
Cheng-i. Weng - One of the best experts on this subject based on the ideXlab platform.
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NUMERICAL MODELLING OF TWIN‐ROLL CASTING BY THE Coupled Fluid Flow AND HEAT TRANSFER MODEL
International Journal for Numerical Methods in Engineering, 1997Co-Authors: J. G. Chang, Cheng-i. WengAbstract:The twin-roll process is modelled by a Coupled Fluid Flow and phase change model by means of a versatile finite element method. Here, a simple numerical scheme is proposed to solve the problem of determining the interface shape under the thermal equilibrium condition. The procedure is based on a finite element method using a transform technique. The simple numerical method provides an efficient and accurate way to find the interface position and shape with arbitrary boundary geometry. This method can easily be implemented on the existing finite element program, and provides a simple and efficient tool to simulate the solidification as well as the Fluid Flow problem of the twin-roll casting process. © 1997 by John Wiley & Sons, Ltd.
