A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to per...A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to perform proppant transport experiments.The typical characteristics of proppant transport and placement in rough fractures and its intrinsic mechanisms are investigated,and the influences of fracture inclination,fracture width and fracturing fluid viscosity on proppant transport and placement in rough fractures are analyzed.The results show that the rough fractures cause variations in the shape of the flow channel and the fluid flow pattern,resulting in the bridging buildup during proppant transport to form unfilled zone,the emergence of multiple complex flow patterns such as channeling,reverse flow and bypassing of sand-carrying fluid,and the influence on the stability of the sand dune.The proppant has a higher placement rate in inclined rough fractures,with a maximum increase of 22.16 percentage points in the experiments compared to vertical fractures,but exhibits poor stability of the sand dune.Reduced fracture width aggravates the bridging of proppant and induces higher pumping pressure.Increasing the viscosity of the fracturing fluid can weaken the proppant bridging phenomenon caused by the rough fractures.展开更多
针对高应变InGaAs/GaAs多量子阱中存在的局域态问题,利用金属有机化合物气相外延(MOCVD)技术,设计并生长了五周期的In_(0.3)Ga_(0.7)As/GaAs高应变多量子阱材料。通过原子力显微镜(Atomic force microscope,AFM)和变温光致发光(Photolum...针对高应变InGaAs/GaAs多量子阱中存在的局域态问题,利用金属有机化合物气相外延(MOCVD)技术,设计并生长了五周期的In_(0.3)Ga_(0.7)As/GaAs高应变多量子阱材料。通过原子力显微镜(Atomic force microscope,AFM)和变温光致发光(Photoluminescence,PL)测试,发现量子阱内部存在缺陷及组分波动的材料无序性表现,验证了多量子阱内部局域态的存在及起源。同时发现在不同测试位置,局域态在低温下对光谱的影响也不同,分别表现为双峰分布和峰位“S”型变化。这进一步说明材料内部无序化程度不同,导致局域态的深度也不同。依据温度-带隙关系的拟合,提出了包含局域态的多量子阱材料的电势分布,并揭示了局域态载流子和自由载流子的复合机制。并且借助变功率PL测试,研究了在不同激发功率密度下不同深度的局域态的发光特性。展开更多
基金Supported by National Key Research and Development Program of China(2022YFE0137200)Outstanding Youth Natural Science Fund of Shaanxi Province(2022JC-37)+2 种基金Innovation Capability Support Program of Shaanxi(2023-CX-TD-31)Natural Science Basic Research Project of Shaanxi Province(2024JC-YBQN-0381)National Natural Science Foundation of China(51874240,52204021)。
文摘A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to perform proppant transport experiments.The typical characteristics of proppant transport and placement in rough fractures and its intrinsic mechanisms are investigated,and the influences of fracture inclination,fracture width and fracturing fluid viscosity on proppant transport and placement in rough fractures are analyzed.The results show that the rough fractures cause variations in the shape of the flow channel and the fluid flow pattern,resulting in the bridging buildup during proppant transport to form unfilled zone,the emergence of multiple complex flow patterns such as channeling,reverse flow and bypassing of sand-carrying fluid,and the influence on the stability of the sand dune.The proppant has a higher placement rate in inclined rough fractures,with a maximum increase of 22.16 percentage points in the experiments compared to vertical fractures,but exhibits poor stability of the sand dune.Reduced fracture width aggravates the bridging of proppant and induces higher pumping pressure.Increasing the viscosity of the fracturing fluid can weaken the proppant bridging phenomenon caused by the rough fractures.
文摘针对高应变InGaAs/GaAs多量子阱中存在的局域态问题,利用金属有机化合物气相外延(MOCVD)技术,设计并生长了五周期的In_(0.3)Ga_(0.7)As/GaAs高应变多量子阱材料。通过原子力显微镜(Atomic force microscope,AFM)和变温光致发光(Photoluminescence,PL)测试,发现量子阱内部存在缺陷及组分波动的材料无序性表现,验证了多量子阱内部局域态的存在及起源。同时发现在不同测试位置,局域态在低温下对光谱的影响也不同,分别表现为双峰分布和峰位“S”型变化。这进一步说明材料内部无序化程度不同,导致局域态的深度也不同。依据温度-带隙关系的拟合,提出了包含局域态的多量子阱材料的电势分布,并揭示了局域态载流子和自由载流子的复合机制。并且借助变功率PL测试,研究了在不同激发功率密度下不同深度的局域态的发光特性。
