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基于高阶格式的高精度化学驱模拟 被引量:1
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作者 朱舟元 李明辉 +1 位作者 雷征东 陈掌星 《石油科学通报》 2018年第2期215-231,共17页
油藏数值模拟的精度取决于网格尺寸,网格越小,模拟结果的精度越高,结果越趋近于收敛。大尺寸网格往往伴随着严重的数值扩散现象。化学驱作为一种复杂的提高采收率过程,由于其复杂的机理(如乳液的相态变化),往往需要很小尺寸的网格以获... 油藏数值模拟的精度取决于网格尺寸,网格越小,模拟结果的精度越高,结果越趋近于收敛。大尺寸网格往往伴随着严重的数值扩散现象。化学驱作为一种复杂的提高采收率过程,由于其复杂的机理(如乳液的相态变化),往往需要很小尺寸的网格以获得精确的模拟结果。本文重点探讨使用高阶格式来改进化学驱模拟的精度。首先对提高油藏数值模拟精度的主流方法进行了全面的分析,包括网格粗化方法、自适应网格加密方法和高阶格式方法。考虑到化学驱模拟的特点,本文选用高阶格式方法对化学驱模拟的精度进行改进提升。随后测试了一维、二维和三维矿场尺度的ASP三元复合驱模拟问题,结果发现模拟的精度高度依赖于所用的网格尺寸。为了获得接近收敛的结果,化学驱所需的网格尺寸远小于水驱模拟。一维化学驱中,网格越粗,表面活性剂分布越"平均化",最终采收率越低。使用二阶和三阶格式,一维、二维和三维矿场尺度三元复合驱模型测试的模拟精度均有大幅提升。使用较粗的网格及高精度格式,即可获得与细网格类似的精度。高精度格式为降低数值黏性、提高精度、降低模拟所需网格数和计算时间,提供了有效的解决办法。该方法也有助于大型油田化学驱的快速精确数值模拟、历史拟合、优化等技术的顺利实施。 展开更多
关键词 油藏数值模拟 化学驱 模拟精度 高阶格式 数值模拟效率
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新型电子阻挡层结构对蓝光InGaN发光二极管性能的提高(英文) 被引量:2
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作者 丁彬彬 赵芳 +7 位作者 宋晶晶 熊建勇 郑树文 喻晓鹏 许毅钦 周德涛 张涛 范广涵 《发光学报》 EI CAS CSCD 北大核心 2013年第3期345-350,共6页
分别对3种不种电子阻挡层的蓝光AlGaN LED进行数值模拟研究。3种阻挡层结构分别为传统Al-GaN电子阻挡层,AlGaN-GaN-AlGaN电子阻挡层和Al组分渐变的AlGaN-GaN-AlGaN电子阻挡层。此外对这对三种器件的活性区的载流子浓度、能带图、静电场... 分别对3种不种电子阻挡层的蓝光AlGaN LED进行数值模拟研究。3种阻挡层结构分别为传统Al-GaN电子阻挡层,AlGaN-GaN-AlGaN电子阻挡层和Al组分渐变的AlGaN-GaN-AlGaN电子阻挡层。此外对这对三种器件的活性区的载流子浓度、能带图、静电场和内量子效率进行比较和分析。研究结果表明,相较于传统AlGaN和AlGaN-GaN-AlGaN两种电子阻挡层的LED,具有Al组分渐变的AlGaN-GaN-AlGaN电子阻挡层结构的LED具有较高的空穴注入效率、较低的电子外溢现象和较小的静电场(活性区)。同时,具有Al组分渐变的AlGaN-GaN-AlGaN电子阻挡层结构的LED的efficiency droop现象也得到一定的缓解。 展开更多
关键词 发光二极管(LED) 电子阻挡层(EBL) 数值模拟 效率下降
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Optimizing the drilled well patterns for CBM recovery via numerical simulations and data envelopment analysis 被引量:3
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作者 Luo Jinhui Yang Yongguo Chen Yuhua 《International Journal of Mining Science and Technology》 2012年第4期503-507,共5页
Coalbed methane(CBM) commercial development requires choosing the arrangement of the wells.This should be done by considering the corresponding input-output(investment-profit) efficiencies.Simulations were obtained fr... Coalbed methane(CBM) commercial development requires choosing the arrangement of the wells.This should be done by considering the corresponding input-output(investment-profit) efficiencies.Simulations were obtained from the computer modeling group(CMG) given the reservoir conditions of the Panzhuang block in the southern part of the Qinshui Basin.This is a demonstration region for CBM development located in Shanxi province of northern China.The sensitivity of gas production from a single vertical well to the primary reservoir parameters was estimated first.Then multi-well gas production from three different well patterns was simulated to estimate the most appropriate well spacing.Combining the investment requirements then gave investment-profit efficiencies for these well patterns.A data envelopment analysis(DEA) model was used to optimize the efficiency.The results show that the permeability,the reservoir pressure,and the gas content have an evident impact on single well gas production.The desorption time has little or no affect on production.The equilateral triangular well pattern(ETWP) in a 400 m well spacing is,for multi-well development,the optimal pattern.It has a better input-output ratio,a longer stable yield time,and provides for greater CBM recovery than does either the rectangular well pattern(RWP) or the five point well pattern(FPWP). 展开更多
关键词 OptimizationWell patternCBMVertical surface drillingNumerical simulationDEA
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Parametric Study of Two-Body Floating-Point Wave Absorber 被引量:6
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作者 Atena Amiri Roozbeh Panahi Soheil Radfar 《Journal of Marine Science and Application》 CSCD 2016年第1期41-49,共9页
In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber... In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber (FPA) with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter's efficiency when considering specific conditions. 展开更多
关键词 floating-point absorber wave energy energy absorption Wave Energy Converter (WEC) Power Take Off (PTO) numerical simulation
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