Application of Seagull Optimization Algorithm Log Interpretation to Shale Gas Reservoir of Well H in Sichuan Basin Yuxi Block

Due to the diversity of mineral types in shale gas reservoirs, it is difficult to establish reservoir parameter volume model by conventional log interpretation methods. The optimization log interpretation method can evaluate complex lithology reservoirs effectively, and the key is optimization algorithm. With the newly proposed seagull optimization algorithm method, we calculate the mineral and physical parameters of shale gas reservoir in Well H of Yuxi block, Sichuan Basin, and compare with the genetic algorithm and the genetic algorithm-complex hybrid algorithm. It shows that calculation results of seagull optimization algorithm optimization log interpretation match well with core analysis data, and calculation error is small, calculation speed is fast. Seagull optimization algorithm also makes up for the shortcomings of premature convergence and easy to fall into local optimization of genetic algorithm, the need for secondary optimization and slow search speed of genetic-complex hybrid algorithm. It provides a reference for the application of seagull optimization algorithm in other shale gas reservoirs regions.     

基于光纤传感及数字图像测试的管-土相互作用试验研究

我国城市化、工业化进程对地下管线的依赖性和需求越来越强,但是近年来相关的重大安全事故频发,亟待加强对管道破坏机理及管-土相互作用的研究。本文基于准分布式光纤布拉格光栅(FBG)技术,在室内开展了一系列平面应变模型试验,利用光纤应变传感器监测了地表加载作用下埋地管道的受力变形特征,据此提出了由应变测值反演管周土压力的计算方法;同时,利用粒子图像测速(PIV)技术获取了管道周边土体的变形规律,并和光纤监测结果进行了对比分析。试验结果表明:采用FBG传感技术,可以有效获取管周土压力分布及土体应变的演化过程;不同埋深率情况下管周土体的变形破坏模式有较大的不同,土拱效应随管道埋深增大而变得更加显著。相关结论为进一步认识埋地管道的灾变机理、提高监测预警水平,提供了一定的参考。     

长短桩组合型复合地基优化设计方法研究

在软土地基上建造建(构)筑物需要进行地基处理,复合地基是一种行之有效的地基处理方式。工程上一般对地基浅层土的承载力要求较高,而深层只需满足下卧层强度要求即可。长短桩复合地基可做到浅层置换率高,深部置换率低,这样就合理地满足了软弱地基不同深度对承载力的要求。同时长短桩复合地基浅部置换率高,加固区复合地基模量大,深部置换率低,复合地基模量较低,正好适应浅部附加应力大,深部附加应力小的应力场,这样对减少软弱地基总沉降有利。本文探讨了长短桩复合地基优化设计方法,提出了长短桩复合地基优化设计数学模型,并利用复合形法求解优化设计数学模型,同时给出了优化设计计算算例,计算结果表明,此优化设计方法不仅可有效地保证长短桩复合地基设计方案技术上可靠,还可获得最佳的经济效益。     

基于月动力延伸预报最优信息的中国降水降尺度预测模型

利用国家气候中心月动力延伸预报结果、NCEP/NCAR再分析资料和中国160个站观测资料,通过计算两次相关的方法,获取最优预报信息作为建立降尺度预测模型的预测因子,提取的最优预测因子同时满足既是观测环流要素场影响降水的关键区域,又是模式要素场预报的高技巧区域两个条件.结合挑选出的最优预测因子,利用最优子集回归建立月平均降水的降尺度预测模型.文中设计了消除预测因子和预测量的线性趋势值后建立预测模型(方案1)和直接利用原始资料建立预测模型(方案2)两种方案.经过独立样本检验,发现这两种方案建立的预测模型都能够提高月尺度降水预测,方案1对月尺度降水预测的距平相关系数平均可达0.35.利用该方案对超前时间分别为0、5、10 d的月动力延伸预报产品进行月降水的降尺度预测表明,模式初值信息不仅影响月动力延伸预报结果,也影响降尺度应用效果,利用超前时间为0和5 d的月动力延伸预报结果进行降水降尺度预测可在业务中参考.此外,降尺度预测模型中选取的预测因子不仪在统计上是显著的,同时也具有清楚的物理意义.     

On Heavy Particle Dispersion in Turbulent Shear Flows: 3-D Analysis of the Effects of Crossing Trajectories

In the approaches used to predict the dispersion of discrete particles moving in a turbulent flow, the effects of crossing trajectories due to gravity (or any other external force field) are generally accounted for by modifying the integral time scales according to the well-known analysis of Csanady (J Atmos Sci 20:201–208, 1963). Here, an alternative theoretical analysis of the time correlation of the fluid velocity fluctuations along a particle trajectory is presented and applied in a turbulent shear flow. The study is carried out in the frame of three-dimensional Langevin-type stochastic models, where the main unknowns are the drift tensor components rather than the conventional integral time scales of the fluid seen by the particles. Starting from a model for the space-time velocity covariance tensor of the turbulence under the assumption of homogeneous shear flow, the various components of the time correlation tensor of the fluid seen are expressed in the asymptotic case of large mean relative velocity (between the particles and the flow) compared to the particle velocity fluctuations. In order to provide comparison with the generally used expressions arising from isotropic turbulence assumption, we examine also the conventional integral time scales of the fluid seen in the directions parallel and perpendicular to the mean relative velocity. The most prominent deviations from isotropic turbulence are observed when the external force field is in the direction of the mean velocity gradient: in this case the loss of correlation in the mean flow direction is significantly lower than expected in a uniform flow, an observation that is in qualitative agreement with the few available data.     

Studies on Adsorptive Desulfurization by Activated Carbon

Sulfur removal using adsorption requires a proper process parametric study to determine its optimal performance characteristics. In this study, response surface methodology was employed for sulfur removal from model oil (dibenzothiophene; DBT dissolved in iso‐octane) using commercial activated carbon (CAC) as an adsorbent. Experiments were carried out as per central composite design with four input parameters such as initial concentration (C₀: 100–900 mg/L), adsorbent dosage (m: 2–22 g/L), time of adsorption (t: 15–735 min), and temperature (T: 10–50°C). Regression analysis showed good fit of the experimental data to the second‐order polynomial model with coefficient of determination R²‐value of 0.9390 and Fisher F‐value of 16.5. The highest removal of sulfur by CAC was obtained with m = 20 g/L, t = 6 h, and T = 30°C.     

波浪环境下多孔射流水动力特性试验

为了研究波浪对多孔射流运动和稀释过程的影响,采用粒子图像测速（PIV）及激光诱导荧光（LIF）量测系统对波浪环境下多孔射流的速度场和浓度场进行了测量。结果表明:在波浪环境下多孔射流可分为3个区域,即初始区、过渡区和混合区。在初始区,各孔射流保持各自的射流特征,相互影响较小;在过渡区,各孔射流发生分叉,并在孔与孔之间相互叠加,形成若干个汇流点,平均速度和平均浓度的峰值从射流轴线位置向汇流点处偏移;在混合区,多孔射流相互融合,其平均速度和平均浓度呈现单一的“坦峰”分布,形式上表现为单孔射流的水动力特征。通过对比分析发现,波高和周期的增大以及射流初始速度的减小可使汇流点的位置向下偏移,多孔射流将更快地进入过渡区和混合区。     

蜗杆凸轮间歇机构的设计及参数选择

用优化设计的观点，论述了蜗杆凸轮间歇（分度）运动机构的工作原理、参数与运动规律的选择、设计方法。     

Groundwater resources management under environmental constraints in Shiroishi of Saga plain, Japan

A sinking of the land surface due to the pumping of groundwater has long been recognized as an environmental issue in the Shiroishi plain of Saga, Japan. Land subsidence can have several negative economic and social implications such as changes in groundwater and surface water flow patterns, restrictions on pumping in land subsidence prone areas, localized flooding, failure of well casings as well as shearing of structures. To minimize such an environmental effect, groundwater management should be considered in this area. In this study, a new integrated numerical model that integrates a three-dimensional numerical groundwater flow model coupled with a one-dimensional soil consolidation model and a groundwater optimization model was developed to simulate groundwater movement, to predict ground settlement and to search for optimal safe yield of groundwater without violating physical, environmental and socio-economic constraints. It is found that groundwater levels in the aquifers greatly vary from season to season in response to the varying climatic and pumping conditions. Consequently, land subsidence has occurred rapidly throughout the area with the Shiroishi plain being the most prone. The predicted optimal safe yield of the pumping amount is about 5 million m³. The study also suggests that pumping with this optimal amount will minimize the rate of land subsidence over the entire area. An erratum to this article can be found at     

Mineral ballast and particle settling rates in the coastal upwelling system off NW Africa and the South Atlantic

The ocean off NW Africa is the second most important coastal upwelling system with a total annual primary production of 0.33 Gt of carbon per year (Carr in Deep Sea Res II 49:59–80, 2002). Deep ocean organic carbon fluxes measured by sediment traps are also fairly high despite low biogenic opal fluxes. Due to a low supply of dissolved silicate from subsurface waters, the ocean off NW Africa is characterized by predominantly carbonate-secreting primary producers, i.e. coccolithophorids. These algae which are key primary producers since millions of years are found in organic- and chlorophyll-rich zooplankton fecal pellets, which sink rapidly through the water column within a few days. Particle flux studies in the Mauretanian upwelling area (Cape Blanc) confirm the hypothesis of Armstrong et al. (Deep Sea Res II 49:219–236, 2002) who proposed that ballast availability, e.g. of carbonate particles, is essential to predict deep ocean organic carbon fluxes. The role of dust as ballast mineral for organic carbon, however, must be also taken into consideration in the coastal settings off NW Africa. There, high settling rates of larger particles approach 400 m day⁻¹, which may be due to a particular composition of mineral ballast. An assessment of particle settling rates from opal-production systems in the Southern Ocean of the Atlantic Sector, in contrast, provides lower values, consistent with the assumptions of Francois et al. (Global Biogeochem Cycles 16(4):1087, 2002). Satellite chlorophyll distributions, particle distributions and fluxes in the water column off NW Africa as well as modelling studies suggest a significant lateral flux component and export of particles from coastal shelf waters into the open ocean. These transport processes have implications for paleo-reconstructions from sediment cores retrieved at continental margin settings.