Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typica...Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.展开更多
The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean ...The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean value of the atom inversion operator 〈 S 3(t)〉 is gi ven. The influence of the “counter rotating term” on the collapse and revival phenomenon is discussed from the comparison between the cases with RWA and without RWA. It shows that the influence of the virtual photon field makes the quantum fluctuations appear on the collapse and revival phenomenon.展开更多
The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structur...The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structural belts,the seven largest of which aggregate proved oil reserves of 7.7× 108 m3,accounting for 86％ of the total discovered reserve in the basin.These second-order structures have one common phenomenon：oil is contained in all traps present in them.In other words,they are all belt-wide petroliferous reservoirs.Research has identified eight types of second-order structural belts under two categories in the eastern PRMB.Their petroliferous properties are subject to three typical constraints：petroliferous properties of subsags hosting these structural belts,locations of these belts in the petroleum system,and availability of traps prior to the hydrocarbon expulsion and migration.The formation and distribution of oil reservoirs in these belts are characterized by subsag-belt integration and ＂three-in-one＂.The former indicates that sags and the second-order structural belts within the supply range of the sags constitute the basic units of hydrocarbon accumulations and are therefore inseparable.The latter indicates that a belt-wide petroliferous second-order structural belt always contains three important elements：hydrocarbon richness,effective pathway and pre-existing traps.展开更多
基金supported by the National Natural Science Foundation of China Joint Fund Project (Grant/Award Number: U20B6003)National Natural Science Foundation of China (Grant/Award Number: 52304054)。
文摘Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.
文摘The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean value of the atom inversion operator 〈 S 3(t)〉 is gi ven. The influence of the “counter rotating term” on the collapse and revival phenomenon is discussed from the comparison between the cases with RWA and without RWA. It shows that the influence of the virtual photon field makes the quantum fluctuations appear on the collapse and revival phenomenon.
文摘The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structural belts,the seven largest of which aggregate proved oil reserves of 7.7× 108 m3,accounting for 86％ of the total discovered reserve in the basin.These second-order structures have one common phenomenon：oil is contained in all traps present in them.In other words,they are all belt-wide petroliferous reservoirs.Research has identified eight types of second-order structural belts under two categories in the eastern PRMB.Their petroliferous properties are subject to three typical constraints：petroliferous properties of subsags hosting these structural belts,locations of these belts in the petroleum system,and availability of traps prior to the hydrocarbon expulsion and migration.The formation and distribution of oil reservoirs in these belts are characterized by subsag-belt integration and ＂three-in-one＂.The former indicates that sags and the second-order structural belts within the supply range of the sags constitute the basic units of hydrocarbon accumulations and are therefore inseparable.The latter indicates that a belt-wide petroliferous second-order structural belt always contains three important elements：hydrocarbon richness,effective pathway and pre-existing traps.
