The Experts below are selected from a list of 17715 Experts worldwide ranked by ideXlab platform
Chuangye Zhang - One of the best experts on this subject based on the ideXlab platform.
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Numerical Simulation of In Situ Combustion of Oil Shale
Geofluids, 2017Co-Authors: Huan Zheng, Weiping Shi, Dali Ding, Chuangye ZhangAbstract:This paper analyzes the process of in situ combustion of oil shale, taking into account the transport and chemical reaction of various components in porous reservoirs. The physical model is presented, including the mass and energy conservation equations and Darcy’s law. The oxidation reactions of oil shale combustion are expressed by adding source terms in the conservation equations. The reaction Rate of oxidation satisfies the Arrhenius law. A numerical method is established for calculating in situ combustion, which is simulated numerically, and the results are compared with the available experiment. The profiles of temperature and volume fraction of a few components are presented. The temperature contours show the temperature variation in the combustion tube. It is found that as combustion reaction occurs in the tube, the concentration of oxygen decreases rapidly, while the concentration of carbon dioxide and carbon monoxide increases contrarily. Besides, the combustion front velocity is consistent with the experimental value. Effects of Gas Injection Rate, permeability of the reservoir, initial oil content, and injected oxygen content on the ISC process were investigated in this study. Varying Gas Injection Rate and oxygen content is important in the field test of ISC.
Qiang Song - One of the best experts on this subject based on the ideXlab platform.
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Determination of the propagation state of the combustion zone during in-situ combustion by dimensionless numbers
Fuel, 2021Co-Authors: Dong Liu, Junshi Tang, Ruonan Zheng, Qiang SongAbstract:Abstract Ensuring the sustainable propagation of the combustion zone is a prerequisite for in-situ combustion (ISC). The combustion zone propagation processes with different Gas Injection parameters and reservoir properties were simulated with CMG STARS and a method of determining the propagation state was proposed based on the theoretical analysis of the simulation results. The simulation results of 67 cases with different Gas Injection parameters and reservoir properties show that there are three states of combustion zone propagation: the sustainable state, the declined state and the extinguished state. The temperature of the combustion zone shows a good correlation with the state of the combustion zone propagation. With increases in the Gas Injection Rate, oxygen concentration, and oil saturation and decrease in the rock permeability, the combustion zone temperature increases and the propagation state changes from the extinguished or declined state to the sustainable state. Analysis of the nondimensionalized energy conservation equation shows that the combustion zone temperature is determined by the two dimensionless numbers HD and CW with the determined core property and domain. A diagram for determining the time-averaged temperature of the combustion zone using the HD and CW numbers was established, with relative deviations within 7%. The combustion zone propagation state under the combination conditions of the Gas Injection Rate, oxygen concentration, oil saturation and reservoir permeability can be judged according to the predicted combustion zone temperature. The proposed method helps optimize the design of Gas Injection parameters in combustion tube tests and ISC oilfield applications.
William R. Rossen - One of the best experts on this subject based on the ideXlab platform.
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Gas-Injection Rate Needed for SAG Foam Processes To Overcome Gravity Override
SPE Journal, 2014Co-Authors: C.s. Boeije, William R. RossenAbstract:Summary Gravity override is a severe problem in Gas-Injection enhanced-oil-recovery (EOR) processes, especially in relatively homogeneous formations. Foam can reduce gravity override. Shan and Rossen (2004) show that the best foam process for overcoming gravity override is one of injecting a large slug of surfactant followed by a large slug of Gas, injected at constant, maximum-allowable Injection pressure. This process works because foam collapses near the Injection well, giving good injectivity simultaneously with mobility control at the leading edge of the Gas bank. The supply of Gas that would be needed to maintain constant Injection pressure is a concern for EOR processes in which Gas is produced industrially or from a separations plant with limited capacity: The available Gas stream may not be sufficient for the optimal process. We show that for such a process, the pressure drop across the foam bank back to the Injection well, at fixed Injection Rate, is nearly constant as the foam bank propagates radially outward. From this result, one can derive a simple formula to predict the Rate of Gas Injection required for each of two limiting cases: An extremely strong foam at the foam front, many times more viscous than the fluids it displaces. In this case, the Rate of Gas Injection required to maintain constant Injection pressure is nearly constant, but Injection Rate is low. A foam just strong enough to maintain mobility control at its leading edge. In this case, Injection Rate required to maintain constant Injection pressure increases steeply with time. Use of the formulae provides a quick initial estimate of how Gas-Injection Rate must vary over the duration of the EOR process to maintain an optimal process. The fit to simulations of surfactant-alternating-Gas (SAG) foam-Injection Rate in a five-spot pattern is remarkably good, especially for strong foam, given the simplicity of the model. In addition, we illustRate how one would determine the properties of a foam that would fit the available Gas stream. This criterion then could guide the development of a surfactant formulation with these properties.
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Gas Injection Rate Needed for SAG Foam Processes to Overcome Gravity Override
Day 1 Mon September 30 2013, 2013Co-Authors: C.s. Boeije, William R. RossenAbstract:Abstract Gravity override is a severe problem in Gas-Injection enhanced-oil-recovery processes, especially in relatively homogeneous formations. Foam can reduce gravity override. Shan and Rossen (2004) show that the best foam process for overcoming gravity override is one of injecting a large slug of surfactant followed by a large slug of Gas, injected at constant, maximum-allowable Injection pressure. This process works because foam collapses near the Injection well, giving good injectivity simultaneously with mobility control at the leading edge of the Gas bank. The supply of Gas that would be needed to maintain constant Injection pressure is a concern for EOR processes where Gas is produced industrially or from a separations plant with limited capacity: the available Gas stream may not be sufficient for the optimal process. We show that for such a process, the pressure drop across the foam bank back to the Injection well, at fixed Injection Rate, is nearly constant as the foam bank propagates radially outward. From this result, one can derive a simple formula to predict the Rate of Gas Injection required for each of two limiting cases: an extremely strong foam at the foam front, many times more viscous than the fluids it displaces. In this case, the Rate of Gas Injection required to maintain constant Injection pressure is nearly constant, but Injection Rate is low. a foam just strong enough to maintain mobility control at its leading edge. In this case Injection Rate required to maintain constant Injection pressure increases steeply with time. Using the formulae provides a quick initial estimate of how Gas Injection Rate must vary over the duration of the EOR process to maintain an optimal process. In addition, we illustRate how one would determine the properties of a foam that would fit the available Gas stream. This criterion then could guide the development of a surfactant formulation with these properties.
Huan Zheng - One of the best experts on this subject based on the ideXlab platform.
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Numerical Simulation of In Situ Combustion of Oil Shale
Geofluids, 2017Co-Authors: Huan Zheng, Weiping Shi, Dali Ding, Chuangye ZhangAbstract:This paper analyzes the process of in situ combustion of oil shale, taking into account the transport and chemical reaction of various components in porous reservoirs. The physical model is presented, including the mass and energy conservation equations and Darcy’s law. The oxidation reactions of oil shale combustion are expressed by adding source terms in the conservation equations. The reaction Rate of oxidation satisfies the Arrhenius law. A numerical method is established for calculating in situ combustion, which is simulated numerically, and the results are compared with the available experiment. The profiles of temperature and volume fraction of a few components are presented. The temperature contours show the temperature variation in the combustion tube. It is found that as combustion reaction occurs in the tube, the concentration of oxygen decreases rapidly, while the concentration of carbon dioxide and carbon monoxide increases contrarily. Besides, the combustion front velocity is consistent with the experimental value. Effects of Gas Injection Rate, permeability of the reservoir, initial oil content, and injected oxygen content on the ISC process were investigated in this study. Varying Gas Injection Rate and oxygen content is important in the field test of ISC.
Dong Liu - One of the best experts on this subject based on the ideXlab platform.
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Determination of the propagation state of the combustion zone during in-situ combustion by dimensionless numbers
Fuel, 2021Co-Authors: Dong Liu, Junshi Tang, Ruonan Zheng, Qiang SongAbstract:Abstract Ensuring the sustainable propagation of the combustion zone is a prerequisite for in-situ combustion (ISC). The combustion zone propagation processes with different Gas Injection parameters and reservoir properties were simulated with CMG STARS and a method of determining the propagation state was proposed based on the theoretical analysis of the simulation results. The simulation results of 67 cases with different Gas Injection parameters and reservoir properties show that there are three states of combustion zone propagation: the sustainable state, the declined state and the extinguished state. The temperature of the combustion zone shows a good correlation with the state of the combustion zone propagation. With increases in the Gas Injection Rate, oxygen concentration, and oil saturation and decrease in the rock permeability, the combustion zone temperature increases and the propagation state changes from the extinguished or declined state to the sustainable state. Analysis of the nondimensionalized energy conservation equation shows that the combustion zone temperature is determined by the two dimensionless numbers HD and CW with the determined core property and domain. A diagram for determining the time-averaged temperature of the combustion zone using the HD and CW numbers was established, with relative deviations within 7%. The combustion zone propagation state under the combination conditions of the Gas Injection Rate, oxygen concentration, oil saturation and reservoir permeability can be judged according to the predicted combustion zone temperature. The proposed method helps optimize the design of Gas Injection parameters in combustion tube tests and ISC oilfield applications.
