32 research outputs found

    Aspect of Clusters Correlation at Light Nuclei Excited State

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    The correlation of αα\alpha\alpha was probed via measuring the transverse momentum pTp_{T} and width δpT\delta p_{T} of one α\alpha, for the first time, which represents the spatial and dynamical essentialities of the initial coupling state in 8^{8}Be nucleus. The weighted interaction vertex of 3α\alpha reflected by the magnitudes of their relative momentums and relative emission angles proves the isosceles triangle configuration for 3α\alpha at the high excited energy analogous Hoyle states.Comment: 8 pages, 9 figure

    Variation of Tensor Force due to Nuclear Medium Effect

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    The enhancement of JÏ€(T)J^{\pi}(T)=3+^{+}(0) state with isospin T=0T=0 excited by the tensor force in the free 6^{6}Li nucleus has been observed, for the first time, relative to a shrinkable excitation in the 6^{6}Li cluster component inside its host nucleus. Comparatively, the excitation of JÏ€(T)J^{\pi}(T)=0+^{+}(1) state with isospin T=1T=1 for these two 6^{6}Li formations take on an approximately equal excitation strength. The mechanism of such tensor force effect was proposed due to the intensive nuclear medium role on isospin TT=0 state.Comment: 6 pages, 4 figure

    Multi-alpha Boson Gas state in Fusion Evaporation Reaction and Three-body Force

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    The experimental evidence for the α\alpha Boson gas state in the 11^{11}C+12^{12}C→\rightarrow23^{23}Mg∗^{\ast} fusion evaporation reaction is presented. By measuring the α\alpha emission spectrum with multiplicity 2 and 3, we provide insight into the existence of a three-body force among α\alpha particles. The observed spectrum exhibited distinct tails corresponding to α\alpha particles emitted in pairs and triplets consistent well with the model-calculations of AV18-UX and chiral effective field theory of NV2-3-la*, indicating the formation of α\alpha clusters with three-body force in the Boson gas state.Comment: 7 pages, 6 figure

    effectsofphysicalparameterrangeondimensionlessvariablesensitivityinwaterfloodingreservoirs

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    The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate

    Numerical simulation on gas production from a hydrate reservoir underlain by a free gas zone

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    Physical and mathematical models of gas production by depressurization from a hydrate reservoir underlain by a free gas zone are established. The mathematical model can interpret the effects of the flow of multiphase fluids, the process of hydrate dissociation, ice-water phase transition, the variation of permeability, the convection and conduction on hydrate dissociation and gas and water production. The evolutions of temperature, pressure, and saturations in the hydrate and free gas zones are elucidated during gas production. The variation of some parameters, such as gas and water rates, with time is presented. The results show that the overlying hydrate zone can supply a certain amount of gas to improve the output of a production well and evidently prolong the lifespan of a gas reservoir

    Influencing Factors Analysis and Optimization of Hydraulic Fracturing in Multi-Layered and Thin Tight Sandstone Gas Reservoir

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    With the deepening of exploration and development of tight sandstone gas reservoirs, the remaining recoverable reservoirs gradually become thinner with the vertical stratigraphic structure. The geomechanical properties become complex, and development based on conventional hydraulic fracturing methods often leads to serious problems, such as difficult control of fracture height, penetrating interlayers, too short fracture length, and inadequate proppant filling. In view of the above problems, we conducted a numerical investigation on a hydraulic fracturing scheme in a multi-layered and thin tight sandstone gas reservoir. According to the dataset from wells in a real gas reservoir in China’s Ordos Basin, the relevant geomechanical characteristics of the gas layers, together with the interlayers in the main production interval, were obtained, based on which, a fine numerical model was developed. By using the PL3D fracture propagation algorithm, a 3D hydraulic fracture propagation model was produced, and then using microseismic monitoring and production data matching, a high-precision hydraulic fracture model of the multi-layered and thin tight sandstone gas reservoir was obtained. On this basis, the influence of different geomechanical parameters and fracturing operational parameters on hydraulic fracture propagation was analyzed. Finally, an optimized hydraulic fracturing scheme that fitted the characteristics of the multi-layered and thin tight sandstone gas reservoir was proposed. Using a typical reservoir example, the optimized scheme enabled control of the fracture height in thin layers and the creation of long fractures with better proppant filling, so that the productivity of the fracture was significantly improved

    The simulation of nature gas production from ocean gas hydrate reservoir by depressurization

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    The vast amount of hydrocarbon gas encaged in gas hydrates is regarded as a kind of future potential energy supply due to its wide deposition and cleanness. How to exploit gas hydrate with safe, effective and economical methods is being pursued. In this paper, a mathematical model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous medium. The model can be used to analyze the effects of the flow of multiphase fluids, the intrinsic kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, the variation of permeability, the convection and conduction on the hydrate dissociation and gas and water production. The numerical results agreed well with the 1-D and 2-D experiments. The numerical results for 3-D hydrate reservoir show that in the first stage of depressurization gas can be produced effectively from hydrate reservoir. With the depletion of reservoir energy because of endothermic process of hydrate dissociation the gas rate decreases rapidly. Then, methods such as thermal stimulation and inhibitor injection should be considered to replace depressurization

    thesimulationofnaturegasproductionfromoceangashydratereservoirbydepressurization

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    The vast amount of hydrocarbon gas encaged in gas hydrates is regarded as a kind of future potential energy supply due to its wide deposition and cleanness. How to exploit gas hydrate with safe, effective and economical methods is being pursued. In this paper, a mathematical model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous medium. The model can be used to analyze the effects of the flow of multiphase fluids, the intrinsic kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, the variation of permeability, the convection and conduction on the hydrate dissociation and gas and water production. The numerical results agreed well with the 1-D and 2-D experiments. The numerical results for 3-D hydrate reservoir show that in the first stage of depressurization gas can be produced effectively from hydrate reservoir. With the depletion of reservoir energy because of endothermic process of hydrate dissociation the gas rate decreases rapidly. Then, methods such as thermal stimulation and inhibitor injection should be considered to replace depressurization

    The Experimental and Numerical Studies on Gas Production from Hydrate Reservoir by Depressurization

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    A set of experimental system to study hydrate dissociation in porous media is built and some experiments on hydrate dissociation by depressurization are carried out. A mathematical model is developed to simulate the hydrate dissociation by depressurization in hydrate-bearing porous media. The model can be used to analyze the effects of the flow of multiphase fluids, the kinetic process and endothermic process of hydrate dissociation, ice-water phase equilibrium, the variation of permeability, convection and conduction on the hydrate dissociation, and gas and water productions. The numerical results agree well with the experimental results, which validate our mathematical model. For a 3-D hydrate reservoir of Class 3, the evolutions of pressure, temperature, and saturations are elucidated and the effects of some main parameters on gas and water rates are analyzed. Numerical results show that gas can be produced effectively from hydrate reservoir in the first stage of depressurization. Then, methods such as thermal stimulation or inhibitor injection should be considered due to the energy deficiency of formation energy. The numerical results for 3-D hydrate reservoir of Class 1 show that the overlying gas hydrate zone can apparently enhance gas rate and prolong life span of gas reservoir
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