压裂支撑剂密度测定方法及应用研究

论证了支撑剂体积密度、视密度和绝对密度的概念与内涵,降低概念混用现象的发生。结合SY/T5018-2006和SY/T5018-2014两个标准,重新设计了测定视密度的方法、步骤和计算式。分析得出100 ml规格密度瓶是50 ml规格密度瓶测量值稳定性的7倍以上;用纯水做测试液比煤油的测量值稳定性高出2倍左右;选用100 ml规格的密度瓶,样品质量大于40 g后,会使测量值更趋稳定。支撑剂的密度指标主要用于压裂施工中的产品优选、压裂液携砂能力、地层造缝能力和变密度加砂压裂等方面。建议除非支撑剂为典型的亲油性物质,否则宜选择纯水、100 ml规格密度瓶、40 g左右支撑剂样品组合开展实验为宜。     

GIS research to address tensions in geography

The rise of Geographic Information Systems (GIS) technologies has been producing powerful tools for spatial data processing, management, analysis, modeling, and visualization. While supporting many tasks, GIS technologies have evoked new thinking and advanced intellectual inquiries in geography. Technological advances in other fields often stimulate new research questions and lead to revolutionary discoveries. The Hubble telescope revolutionizes our understanding of the universe, and 3D digital microscopes transform our knowledge of the coordination among biological, neurological, and physiological systems in living organisms. Can GIS claim similar revolutionary effects on geography? The answer is much up for debate. With GIS technologies, geographic studies can explore a broader extent across multiple scales in space and time and tackle problems through increasingly complex spatial statistics, visual analytics, computation, simulation, machine learning, and artificial intelligence. Both the Hubble telescope and 3D digital microscope were built based on scientific research that subserves the technological advances for inquiries into space and life systems. Likewise, GIScience research innovates GIS methods that enable novel geographic investigations and therefore contribute to geographic knowledge production. For the sake of simplicity, the term GIS used here represents both GIScience and GIS technologies. This essay attempts to clarify the intellectual contributions of GIS to geography on the following two questions: (1) What novel geographic thinking is driven by GIS? (2) How may GIS provoke new geographic inquiries and knowledge? Building on Nystuen's notion of four tensions that trigger geographic questions, the essay discusses how GIS innovations mediate historical tension, space‐time tension, dimensional tension and scale tensions.     

Probability Distribution of the Hull Motion and Mooring Line Tension of Two Floating Systems

The statistical and distribution characteristics of the responses of a floater and its mooring lines are essential in designing floating/mooring systems.In general,the dynamic responses of offshore structures obey a Gaussian distribution,assuming that the structural system,and sea loads are linear or weakly nonlinear.However,mooring systems and wave loads are considerably nonlinear,and the dynamic responses of hull/mooring systems are non-Gaussian.In this study,the dynamic responses of two types of floaters,semi-submersible and spar platforms,and their mooring lines are computed using coupled dynamic analysis in the time domain.Herein,the statistical characteristics and distributions of the hull motion and mooring line tension are discussed and compared.The statistical distributions of the dynamic responses have strong non-Gaussianity and are unreasonably fitted by a Gaussian distribution for the two floating and mooring systems.Then,the effects of water depth,wave parameters,and low-frequency and wave-frequency components on the non-Gaussianity of the hull motion,and mooring line tension are investigated and discussed.A comparison of the statistical distributions of the responses with various probability density functions,including the Gamma,Gaussian,General Extreme Value,Weibull,and Gaussian Mixture Model(GMM)distributions,shows that the GMM distribution is better than the others for characterizing the statistical distributions of the hull motion,and mooring line tension responses.Furthermore,the GMM distribution has the best accuracy of response prediction.     

甘肃北山古岛弧期后张裂带及海相火山岩金矿

甘肃北山地区古生代处于塔里木、哈萨克斯坦与西伯利亚三大板块聚合部位。晚古生代(D₂-D₂)形成岛弧带和弧后盆地,之后又处于板内构造演化时期,石炭纪-二叠纪有拉张-闭合构造运动,形成规模较大的火山喷发活动和岩浆侵入作用,对金矿的形成提供了有利条件。本区划分出4条张裂带,每条张裂带控制着金矿床(点)的分布。从金矿成矿构造环境,成矿机制及矿床地质特征分析,本区金矿床属于海相火山岩型金矿。     

基于最小能耗的海洋浮式平台位置轨迹优化

【目的】研究解决海洋大惯量浮式平台在复杂海况影响下所引起的振动冲击问题。【方法】采用逆运动学分析方法对平台回转位置进行优化研究,提出一种基于关节最小耗能的多目标轨迹优化算法。采用分段样条插值方法构造关节位置曲线,并建立关节能耗轨迹优化模型,采用粒子群算法实现对关节位置的优化搜索,从而得到基于平台转动最小耗能的位置优化轨迹。【结果与结论】所采用的轨迹优化方法能有效改善系统运行的平滑性,降低回转机构振动与冲击的影响程度,可为平台的振动与冲击主动控制提供必要的理论依据。     

Visualisation of bacterial degradation and mobilisation of oil in a porous medium

 Bacterial interaction with oil and sea water, in a porous medium, was studied using a transparent micro model mounted on a cybernetic-controlled positioning board of an inverted microscope. This was interfaced with computer-operated image analysis and surveillance equipment. Consecutive flooding of the model allowed oil to become trapped by capillary forces. Hydrocarbonoclastic bacteria were inoculated. The interaction of biofilm and oil was monitored during a period of 25 days, while mineral salts were supplied intermittently. A unique feature of biofilm behaviour was discovered. The phenomenon is discussed, and calculations are presented. A possible explanation of the phenomenon appears to be local reductions of the surface tension. The phenomenon helps explain why bacteria are able to mobilise oil trapped by capillary forces without reducing the interfacial tension to a level that leads to an increase in the capillary number sufficient to explain incremental oil recovery. The experimental design is believed to be suitable for studying biofilm behaviour on the pore level. Received: 26 January 1998 · Accepted: 9 July 1998     

锚拉杆张拉力和摩阻力的现场实验研究与分析

对锚拉桥台锚拉杆进行了２０小时的现场试验,获得了大量实验数据,对张拉后锚拉杆的张拉力与长度、时间、温度和焊接接头的关系以及土对锚拉杆的摩阻力变化及分布规律作了分析与研究。研究结果对指导该类构筑物的设计与施工有着重要的理论与工程实用价值。     

冲绳海槽现代张裂的地球物理特征

位于东海陆架与琉球岛弧之间的冲绳海槽为板块俯冲作用形成的弧后断陷盆地,具有独特的构造地貌特征。自中新世末以来历经了4个强烈拉张的演化时期,目前已达到张裂的高级阶段。地球物理资料显示,海槽中的现代拉张作用仍在进行,表现在海槽轴部快速沉降形成地堑槽,对称分布的张性断裂,晚更新世—全新世以来的岩浆活动,从老至新排列的磁异常务带以及高地热流、频繁的地震活动等,充分体现了冲绳海槽的现代扩张特点。     

畸形波作用下张力腿浮式风力机动力响应特性

针对张力腿系泊浮式风力机的基础运动,忽略柔性构件的影响,建立气动—水动—系泊非线性耦合运动方程。在运动控制方程中包含张力腿系泊系统的非线性回复刚度,桨距角控制以及浮式基础运动对空气动力载荷的影响。在波浪载荷的计算中考虑二阶波浪载荷的作用。采用随机频率相位角调制法生成畸形波波面时历,计算在畸形波作用下张力腿型浮式风力机的动力响应特性。数值模拟结果表明,在畸形波作用下,浮式基础的运动及空气动力性能均受到了显著的影响。其中浮式基础的纵荡和纵摇运动分别受二阶差频与和频波浪力的影响,而垂荡运动的增加则主要是受下沉运动的影响。在畸形波经过的时刻,风力机的功率系数迅速下降,水平方向的风载荷波动先减小,随后其数值急剧下降,而垂直方向的风载荷波动增大。     

Effect of geometric and material discontinuities on the reeling of pipelines

The winding and unwinding of a pipeline onto a large diameter reel as practiced in the reeling installation method, induces bending strains of 1–3% followed by straightening, and reverse bending. The operator must ensure that such plastic deformations are sustained free of local buckling or rupture in the line. Such failures are for example precipitated by pipeline discontinuities in wall thickness and yield stress as they act as stress risers, lead to localized deformations severe enough to result in local buckling. The effect of such discontinuities is studied using a large-scale nonlinear finite element model that simulates the reeling/unreeling of a pipeline. Nonlinear kinematic hardening is used to capture the elasto-plastic behavior of the material imposed by the bending/reverse bending history. Discontinuities in wall thickness and yield stress are shown to result in sharp local changes in curvature that extend over 3–4 pipe diameters accompanied by severe local straining and ovalization. The extent of the disturbance is governed by the bending strain imposed by the ratio of pipe to reel diameter. It can be reduced by an increase in the applied tension but at the expense of additional ovalization of the pipeline. It can also be reduced by increasing the pipe wall thickness but with the consequent increase in costs. A parametric study of the effect of such discontinuities demonstrates that for some combinations of process parameters, the disturbance can lead to local buckling either during winding or unwinding. It is concluded that a modeling framework such as the one presented should be used to generate a design protocol for reel-installed pipelines.