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Riyaz Kharrat - One of the best experts on this subject based on the ideXlab platform.
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Proper Implementation of Gas-oil Gravity Drainage Transfer Functions in Dual Porosity Simulators
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2015Co-Authors: Rohaldin Miri, S. R. Shadizadeh, Riyaz KharratAbstract:Free fall and forced Gravity Drainage are established production mechanisms, which contribute to significant oil production in naturally fractured reservoirs, commonly 30–60% original oil in place. Accurate and proper implementation of Gravity Drainage performance, as an exchange term, in dual porosity simulators is a critical issue. A numerical model of gas-oil Gravity Drainage was developed and solved analytically for some simple cases and also numerically for more complicated forms of capillary pressure and relative permeabilities. In this article, three famous transfer functions in the literature in a comparative study were checked by a developed numerical model. The result revealed that transfer functions studied here predict less accurate results in comparison with the numerical model and using constant matching parameters cannot resolve this issue because problems arise from simple treatment of time dependent parameters, such as capillary pressure and relative permeability.
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The Proper Simulation of Free Fall Gravity Drainage in the Commercial Simulator Environment
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2013Co-Authors: O. Bina, Riyaz Kharrat, S. R. ShadizadehAbstract:Free fall Gravity Drainage is one of the most efficient mechanisms identified in the gas-invaded zone of naturally fractured reservoirs. It is believed that Gravity Drainage could result in very high displacement efficiency. In spite of this importunity, there is a lack of theoretical, experimental, and simulation works on investigation of this recovery process. In this study, a new approach is proposed for simulation of free fall Gravity Drainage called tank model approach. The commercial numerical simulator could be used as a platform to be able to perform this new approach properly. A simulator is selected as an appropriate environment since its fine grid simulation will lead to obtain the most proper results. The fine grid simulation as a numerical approach includes fewer simplifications comparing with available mathematical modeling and, consequently, the results are more accurate by considering numerical models. As a result, the tank model approach is properly performed for simulating the free fall ...
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The Scaling of the Gas-assisted Gravity Drainage Process Using Dimensionless Groups
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2013Co-Authors: S. E. Sadati, Riyaz KharratAbstract:Scaling of the gas-assisted Gravity Drainage process using inspectional analysis leads to a better understanding of the process. Seven scaling groups were derived by using inspectional analysis for the gas-assisted Gravity Drainage process and were reduced to five independent dimensionless groups. Based on these five dimensionless groups, a new dimensionless group was proposed for better representing all factors and forces that affect the process. The newly proposed dimensionless group was derived from experimental data in the literature and was validated by using reservoir simulation data. This number that is derived from experimental data in the core scale can predict oil recovery in reservoir scale by some modification in Gravity number.
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Flow Regime Characterization of the Gas-assisted Gravity Drainage Process
Energy Sources Part A: Recovery Utilization and Environmental Effects, 2013Co-Authors: S. E. Sadati, Riyaz KharratAbstract:Flow regime characterization is helpful in designing efficient gas injection programs in commercial floods. Lenormand et al.'s (1988) phase-diagram is commonly used for flow regime identification of Gravity Drainage. Lenormand's phase-diagram was developed using horizontal micro-model displacement experiments, whereas the gas-assisted Gravity Drainage process is vertical displacement, so Lenormand et al.'s plot is not applicable for gas-assisted Gravity Drainage floods. Inspection of the recovery plots against dimensionless numbers and physical interpretation of dimensionless groups guide flow regime identification. Oil recovery of the gas-assisted Gravity Drainage process was calculated by using a black oil simulator at different injection rates and aspect ratios. Flow regime of the gas-assisted Gravity Drainage process was developed based on Gravity number and capillary number at different aspect ratios.
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A New Approach to the Modeling of a Simple Re-infiltration Gravity Drainage Process in Naturally Fractured Reservoirs
Petroleum Science and Technology, 2012Co-Authors: Reza Askarinezhad, Riyaz Kharrat, S. R. ShadizadehAbstract:Abstract One of the most important concerns regarding prediction of production performance in naturally fractured reservoirs is the issue of re-infiltration phenomena. In this study, the modeling of a simple re-infiltration process with no effect of capillary continuity between blocks is presented by extending the Gravity Drainage mechanism for a single block. First, a qualitative analysis of the Gravity Drainage process through porous media was conducted and the role of Gravity and capillary forces was investigated. Then a model for one-dimensional Gravity Drainage in a single block was developed in dimensionless form, a modified version of which can be found in the literature. Then, using the method of separation of variables, the corresponding partial differential equation was solved for a single block with certain boundary and initial conditions. The upper boundary is a no-feed boundary and at the lower boundary the gas saturation is always zero. At the initial condition, the gas saturation is equal t...
A. K. Turner - One of the best experts on this subject based on the ideXlab platform.
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two modes of sea ice Gravity Drainage a parameterization for large scale modeling
Journal of Geophysical Research, 2013Co-Authors: A. K. Turner, Elizabeth C Hunke, Cecilia M BitzAbstract:[1] We present a new one-dimensional parameterization of Gravity Drainage implemented in an all-new thermodynamic component of the Los Alamos Sea Ice Model (CICE), based on mushy layer theory. We solve a set of coupled, nonlinear equations for sea-ice temperature (enthalpy) and salinity using an implicit Jacobian-free Newton-Krylov method. Time resolved observations of Gravity Drainage show two modes of desalination during growth. Rapid Drainage occurs in a thin region just above the ice/ocean interface, while slower Drainage occurs throughout the ice. Parameterizations are designed to represent each of these modes and work simultaneously. Near the interface, desalination occurs primarily via the fast Drainage, while slow Drainage continues to desalinate ice above the interface. The rapid desalination is convectively driven and is parameterized based on a consideration of flow driven upward within the mush and downward in chimneys, modified by the Rayleigh number. The slow desalination is represented as a simple relaxation of bulk salinity to a value based on a critical porosity for sea-ice permeability. It is shown that these parameterizations can adequately reproduce observational data from laboratory experiments and field measurements.
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Two modes of sea-ice Gravity Drainage
2012Co-Authors: A. K. TurnerAbstract:Adrian K. Turner, Elizabeth C. Hunke, T-3; Cecilia M. Bitz, University of Washington Processes that change the vertical salinity profile of sea ice have a significant impact on sea-ice properties and biogeochemistry. One of the most important processes affecting sea-ice salinity is Gravity Drainage where cold, dense brine within newly formed sea ice drains out and is replaced by seawater, resulting in a significant desalination of the sea ice. Using time-resolved bulk salinity and temperature observations of forming sea ice, we show that Gravity Drainage occurs as two distinct modes: (1) rapid Drainage at the base of the ice and (2) slow Drainage occurring more deeply in the ice. We have developed a parameterization for Gravity Drainage that includes these two modes and is suitable for inclusion in a global climate model. The parameterization is included in an all-new thermodynamic component, based on mushy layer theory, for the LANL sea ice model (CICE).
Cecilia M Bitz - One of the best experts on this subject based on the ideXlab platform.
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two modes of sea ice Gravity Drainage a parameterization for large scale modeling
Journal of Geophysical Research, 2013Co-Authors: A. K. Turner, Elizabeth C Hunke, Cecilia M BitzAbstract:[1] We present a new one-dimensional parameterization of Gravity Drainage implemented in an all-new thermodynamic component of the Los Alamos Sea Ice Model (CICE), based on mushy layer theory. We solve a set of coupled, nonlinear equations for sea-ice temperature (enthalpy) and salinity using an implicit Jacobian-free Newton-Krylov method. Time resolved observations of Gravity Drainage show two modes of desalination during growth. Rapid Drainage occurs in a thin region just above the ice/ocean interface, while slower Drainage occurs throughout the ice. Parameterizations are designed to represent each of these modes and work simultaneously. Near the interface, desalination occurs primarily via the fast Drainage, while slow Drainage continues to desalinate ice above the interface. The rapid desalination is convectively driven and is parameterized based on a consideration of flow driven upward within the mush and downward in chimneys, modified by the Rayleigh number. The slow desalination is represented as a simple relaxation of bulk salinity to a value based on a critical porosity for sea-ice permeability. It is shown that these parameterizations can adequately reproduce observational data from laboratory experiments and field measurements.
Serhat Akin - One of the best experts on this subject based on the ideXlab platform.
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Microwave Assisted Gravity Drainage of Heavy Oils
Proceedings of International Petroleum Technology Conference, 2008Co-Authors: Birol Demiral, Serhat Akin, Cagdas Acar, Berna HascakirAbstract:Conventional EOR methods like steam-injection are usually not cost effective for deep wells and wells producing from thin pay zones, due to excessive heat loss to the overburden. For such wells minimizing heat losses can be achieved by using microwave heating assisted Gravity Drainage. In this study, the feasibility of this method was investigated. Heavy oil samples from conceptual reservoirs (Bati Raman (9.5 API), Garzan (12 API) and Camurlu (18 API)) in south east Turkey were used. Using a novel graphite core holder packed with crushed limestone premixed with crude oil and water effects of operational parameters like heating time and waiting period as well as rock and fluid properties like porosity, permeability, wettability, salinity, and initial water saturation were studied.
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Mathematical modeling of steam-assisted Gravity Drainage
Computers & Geosciences, 2006Co-Authors: Serhat AkinAbstract:A mathematical model for Gravity Drainage in heavy-oil reservoirs and tar sands during steam injection in linear geometry is proposed. The mathematical model is based on experimental observations that the steam zone shape is an inverted triangle with the vertex fixed at the bottom production well. Both temperature and asphaltene content dependence of viscosity of the drained heavy oil and their impact on heavy oil production are considered. The developed model has been validated using experimental data presented in the literature. It is seen that the oil production rate is affected as the asphaltene content of the crude oil changes as a function of temperature. The oil production rate conforms well to previously published data covering a wide range of heavy oils and sands for Gravity Drainage.
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A laboratory study of single-well steam-assisted Gravity Drainage process
Journal of Petroleum Science and Engineering, 2001Co-Authors: Serhat Akin, Suat BagciAbstract:Abstract An investigation of the optimization of startup procedure for single-well steam-assisted Gravity Drainage (SW-SAGD) was made as the project economics are influenced significantly by the early production response. An experimental investigation of two early-time processes namely cyclic steam injection and steam circulation to improve reservoir heating is discussed and compared to continuous steam injection as well as other well configurations like vertical injector–horizontal producer and horizontal injector–horizontal producer. Crushed limestone saturated with heavy oil (12.8° API) and water was packed in a laboratory model for the experiments. The effectiveness of the methods is compared within themselves and to conventional steam-assisted Gravity Drainage (SAGD) by measuring the size of the steam chamber as a function of time. The steam chamber area for cyclic steam injection is slightly greater than that of steam circulation case. Furthermore, numerical simulation studies of different early-time processes were conducted and compared to the experimental data using a commercial simulator. It was observed that the numerical model results underestimated the cumulative oil recovery and the steam chamber size. Results from this study, including cumulative recoveries, temperature distributions, and production rates display the differences between the methods.
Francis A. L. Dullien - One of the best experts on this subject based on the ideXlab platform.
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Application of Gravity Drainage to the recovery of residual LNAPL in homogeneous and lensed sand packs
Journal of Contaminant Hydrology, 1995Co-Authors: Lionel J.j. Catalan, Francis A. L. DullienAbstract:Abstract Residual LNAPL (light non-aqueous-phase liquid) trapped as immobile, isolated blobs under the water table often constitutes a large fraction of the total amount of LNAPL in the subsurface. When the water table is lowered using pumping wells, these blobs are remobilized on contract with the layer of free LNAPL that lies on top of the water table. In the dewatered zone above the LNAPL layer, the LNAPL phase is kept continuous by LNAPL films which spread between water coating the pore walls and air occupying the centre of the pores. The LNAPL films can flow under the action of Gravity forces, resulting in the accumulation of LNAPL on top of the water table where it can be recovered. Extremely small residual LNAPL saturations in the dewatered zone can be eventually achieved by Gravity Drainage. However, Gravity Drainage is a slow process due to the low conductivity of LNAPL films. Two experiments have been carried out in a two-dimensional laboratory model packed with sand. In the first experiment, the time scale involved in the recovery of residual Soltrol oil 100® by Gravity Drainage in a homogeneous sand pack was investigated. In the second experiment, a heterogeneous (lensed) sand pack has been used to study: (1) the influence of different-permeability lenses on the spatial distribution of LNAPL leaked at the top of the sand pack; (2) the effects of water table fluctuations; and (3) the recovery of residual LNAPL by Gravity Drainage in a lensed porous medium. Special attention has been given to the case where the lenses have smaller permeability than the surrounding medium.
