基于分层假设的Green-Ampt模型改进

传统Green-Ampt入渗模型由于假设过于简化而限制了计算精度,针对这一问题,在分层假设的基础上对模型进行了改进:将均质入渗土壤分为饱和层、过渡层和干土层,采用Richards模型分析了不同入渗条件下各层的厚度以及各层内含水率和导水率的变化规律,结果表明,入渗条件一定时,过渡层占湿润层(包括饱和层和过渡层)比例会随湿润层厚度的增加线性减小,积水深度和土壤初始含水率分别会影响这一线性关系的纵轴截距和斜率,而土壤饱和导水率则对其没有明显影响;过渡层内土壤含水率分布为椭圆形曲线,而导水率随深度增加线性减小。在此基础上,通过引入湿润层的等效导水率并相应给出锋面吸力的计算方法,对传统Green-Ampt模型进行了改进。结果显示,改进后模型计算精度显著提高。     

一种基于沉积模式的多点地质统计学建模方法

地下储层分布是位置的函数,不同位置处的沉积模式具有差异性。在储层预测时,除了挖掘已有资料所提供的结构和统计信息外,还应该引入待估点位置的信息,以反映沉积储层模式随位置变化的非平稳特征。提出了一种基于沉积模式的多点地质统计学方法,通过距离函数将储层特征与沉积位置相关联,采用整体替换、结构化随机路径以及多重网格策略再现沉积模式。基于现代鄱阳湖沉积所建立的合成非平稳性三角洲前缘沉积地层建模表明,新设计的方法较传统的建模方法更好地反映了三角洲相沉积地层非平稳沉积模式,新设计方法有更好的地质适用性。研究丰富了储层三维建模理论和方法,为实际油藏建模提供了新手段。     

Mixing and transport near the shallow-crested Rumble III seamount and the implications for plankton distribution

Vessel-based observations of water column structure and flow near a shallow-crested seamount are used to quantify the physical disturbance induced by that seamount. The implications of this disturbance on the ‘feeding hole’ hypothesis are then examined based on data from moored thermistors and acoustic current profilers, as well as vessel-based acoustic sounding-derived biomass estimates, currents, and conductivity-temperature-depth profiles from a 55 km square grid of stations around the crest. Mean currents in the region of 0.2 m s^?1 are comparable to observations from surface drifters whereas the semidiurnal tidal flow amplitude was one third of this. Thorpe Scale-based estimates of energy dissipation rate were in the range 10^?9 to 2.10^?8 W kg^?1 and vertical diffusivities K_z were in the range 10^?4 to 10^?3 m² s^?1. Turbulence levels were higher upstream of the seamount–likely due to the influence of nearby seamounts Rumble IV and V. There was no evidence of a Taylor Cap in the Rumble III velocity field. The sounder data provide some evidence of a feeding hole and analysis based on diffusivities suggests that this might persist downstream of the seamount for as much as 7 days.