Search

Objective The oil - increasing effect of in-situ carbon dioxide foam was gradually weakened in multicycle profile control. It was urgent to analyze the decreasing law of the system. Methods The paper studied the law of in-situ carbon dioxide foam profile control with multiple rounds by using large scale visual plate physical model and numerical simulation model which combined with the characteristics of vertical heterogeneity in Bohai oil field reservoir. And an attempt was made to extend the reaction time of the system to increase its action distance. Results The research showed that water flooding could only sweep the high permeability layer in the lower part of the reservoir, but it could not sweep the low permeability layer in t he upper part. The in-situ carbon dioxide foam profile control system could entered the high permeability layer to form plugging and started the low permeability layer, which improved oil recovery more than 10 % in t he first cycle of profile control. But the system could not enter the deeper location with the profile control rounds increased. The enhanced oil recovery value constantly decreased, which was less than 1% by the fourth cycle of profile control. The remaining oil of the high permeability layer was mainly distributed in the two wings and the remaining oil of the low permeability layer was evenly distributed. Conclusions The effective distance of in-situ carbon dioxide foam system was short which was failed to work in deeper reservoir with the profile control rounds increased. T he effect of multicycle profile control was better by prolonging the reaction time to increase its effective distance, which increased the total enhanced oil recovery value by :3. 66%. [ABSTRACT FROM AUTHOR]

The steam injection technology of horizontal wells has become an important heavy oil reservoir production technology. Due to the large length of horizontal section and reservoir heterogeneity, the actual steam distribution effect was poor. In this paper. Fluent was used to simulate reservoir temperature changes and reservoir steam absorption capacity under different steam. injection well structures. A three-dimensional material model experiment platform for horizontal well steam distribution was designed. the temperature field changes in reservoirs of different pipe strings under homogeneous reservoirs was analyzed. The results showed that the reservoir temperature and segmented steam absorption amount obtained by uniform perforation string decreased gradually from the heel end to the toe end of injection well. The reservoir temperature and segmented steam absorption amount were uniform by infilling the perforation of toe end. The temperature field development of slit pipe and uniform perforation pipe string mainly focused on the heel end of steam injection well, while the toe end developed slowly or even not. After infilling the perforation of toe end, and the temperature field was basically parallel to the steam injection well to advance equably.. then the uniform steam distribution was realized, which is corresponding to the numerical simulation results. [ABSTRACT FROM AUTHOR]

In the middle and later stages of shale gas production, the output declines and the pressure of the gas well decreases. In order to ensure smooth transmission of the product gas, the gas compressor is needed to boost production. Because the shale gas has more particulate impurities than conventional gas, if the impurities are not separation incompletely and go into the downstream, it will cause compressor damage even shut down, which will affect the shale gas production and gathering process, causing huge economic losses. As the last guarantee before shale gas entering the supercharger, the separation efficiency of filter separator is very important. But there are few studies on separation efficiency of horizontal filter separator by numerical calculation method. In this paper, FLUENT software is used for numerical simulation of the horizontal filter separator, and the flow field in the equipment is researched and analyzed. The calculation results show that the filter barrel of horizontal separator can effectively separate solid and liquid particles/ impurities. The separation efficiency is high when the liquid particle size is larger than 60μm and the solid particle size is larger than 30 μm, The overall separation efficiency can reach more than 96% . This method can effectively protect the the compressor lever, optimize the shale gas gathering and transportation technology, and ensure the safe operation of shale gas field. [ABSTRACT FROM AUTHOR]

Gas field development blocks are generally divided into three systems such as nature gas gathering and transmission system, purification system and export system, among which accidents in any link will directly threaten the overall production safety of gas field. As an important part of security system, emergency chain system is worth studying. In this paper, a method for analyzing the emergency chain condition of gas field system is developed by clarifying the emergency chain shutdown logic, identifying the main risks, conducting numerical simulation, analyzing the result data and proposing the problem. This method has been successfully applied to the system of a gas reservoir, which provides a theoretical support for the safe production and operation of the production unit surface system. [ABSTRACT FROM AUTHOR]

When using hydraulic fracturing to extract shale gas. the solid impurities are generally carried out. such as mud and sand in the production process. While the gas flows carrying sand in the pipeline, the key components such as elbow will be rushed for the loo high speed, then resulting in erosion and hidden danger to the safe operation of the pipeline. In this paper, the prop-carrying capacity of shale gas pipeline was simulated on the base of API RP 14E model in LedaFlow, the effect of the pipe diameter, pressure and flow rate on erosional velocity limit was analyzed, then the maximum erosion loss of pipe wall corresponding to the erosional velocity limit was calculated by Fluent numerical simulation, and finally the relationship of them were given. This formula not only solves the problem that LedaFlow can not calculate the erosion loss of pipe wall, but also simplifies the complex calculation process of Fluent software, which provides a reference for practical production. [ABSTRACT FROM AUTHOR]

In order to study the distribution of H2S gas diffusion flow field in different building layout, CFX computational fluid dynamics software was used to simulate the H2S gas diffusion flow field under seven different building layout conditions in this paper. Furthermore, an example of verification was presented based on the building complex of a natural gas purification plant. The conclusions were listed as follows:(1) the stagnant area of gas velocity is closely related to the building layout, and the dead zone often occurs on the leeward side of the buildings while the air velocity would increase at the gap between the buildings; (2) the larger the width of the windward side of buildings is, the greater the stagnant area and area of leeward side of buildings are; (3) the CFX could be applied to simulate the air flow movement in complex building layout properly and provided a theoretical basis for the establishment of escape route after H2S gas leakage accident. [ABSTRACT FROM AUTHOR]

Abstract: The increasing importance of liquefied natural gas (LNG) to global energy demand has increased interest in possible hazards associated with its storage. In this paper, a model of vapor dispersion from large-scale LNG tank was established using three-dimensional numerical simulations. Baffle and three sizes of cofferdams were designed for optimization researches. Under low wind speed condition, simulations were conducted to investigate the effects of barriers on the vapor cloud dispersion by using Fluent software. The results showed that, at the start of dispersion, the height of cofferdam was identified to be the key factor in blocking vapor dispersion in the horizontal direction and the cofferdam would delay the vapor dispersion by 3 — 6 min. However, baffle does not make the downwind dispersion distance shorter, but increase the distance by 5. 2%. The findings and analysis presented here will serve as an important theoretical support for LNG plant safety design and emergency procedures. Key words: LNG tank, dispersion, Fluent, barrier, numerical simulation [ABSTRACT FROM AUTHOR]

In order to solve the unstable combustion process of natural gas combustion furnace due to increase of nitrogen content in natural gas caused by the injection of nitrogen in Tahe Oilfield.based on the numerical simulation software Fluent, which is for the tower-linked natural gas containing nitrogen in the furnace conical combustion chamber, the distribution law of temperature field and the formation law of combustion product NOs are researched in this paper. According to the particularity of the natural gas component of the nitrogen of the tower, the combustion efficiency, NO, content, ignition temperature and healing value and Webbo index used as the benchmark for the blending scheme, four blending schemes are calculated and compared. A nitrogen-containing natural gas blending scheme based on NO, content, which will ensure the combustion efficiency, ignition temperature and calorific value and Webbo index of the tower-linked natural gas containing nitrogen is selected. At the same time, this scheme will effectively reduce the environmental pollution caused by nitrogen oxides, and has strong practical significance. [ABSTRACT FROM AUTHOR]

In order to study the leakage and diffusion of LPG spherical tank, a three-dimensional model of spherical tank by taking a spherical tank as reference, was established based on a computational fluid dynamics software FLUENT. The danger zone after the leakage of natural gas was determined according to LPG explosion limit of 1. 5% — 9. o%. Simulation results showed that the leakage and diffusion laws of LPG and further the danger zone of the leakage and diffusion of LPG could be predicted based on these factors. This paper provided a reference for the prevention, control and emergency escape of similar accidents. [ABSTRACT FROM AUTHOR]

Taking the tight sandstone reservoir of the upper Triassic, Xu Jiahe group in the Sichuan central region as an example, combing with the reservoir numerical simulation, then analyzing the qualitative and quantitative influences of injection rate, injection concentration of surfactant, injection PV number on the recovery efficiency of tight sandstone reservoir, this paper focuses on the problem of the tight oil reservoir’s low recovery, and also forecasts the effect of the different surfactant flooding scheme, then presents the best plan in this reservoir condition, and acquires the main control factors of the surfactant flooding. [ABSTRACT FROM AUTHOR]

Knock-out drum in the flare system can avoid rain of fire because it can effectively separate droplets or solid impurities from the vent gas and reduce the amount of condensate in the gas. Therefore, knock-out drum plays a key role for the safety of the flare system and the protection of the environment. In the paper, FLUENT software was applied to simulate the effect of droplet diameter, the pressure difference between the inlet and outlet, working temperature, liquid holdup of the gas and length-diameter ratio on separation efficiency of horizontal knock-out drum. The results showed that properly increasing the droplet diameter, working temperature and length-diameter ratio of knock-out drum, decreasing the pressure difference of the inlet and outlet, liquid fraction can benifit to increase the separation efficiency of the knock-out drum. [ABSTRACT FROM AUTHOR]