GA-BP神经网络在罗源湾口波浪模拟研究中的应用

由于BP神经网络存在收敛速度慢和易于陷入极小值等缺点,引入遗传算法(GA)对网络的权值和阈值加以优化,并采用不同组合的输入因子和样本数,对福建省罗源湾口的波浪进行模拟研究.对输入因子的分析结果表明,研究区域的波浪主要受台湾海峡波浪传播影响,与局地气象因子(风速、风向、海气温差)的相关性较弱.训练样本试验表明,30 d以上的波浪历史数据可使GA-BP神经网络充分学习研究区域的波浪特征,从而实现对波浪要素的高精度模拟.模拟结果显示,对春、夏季实测波浪数据的模拟效果均很好,其中相关性分别为0.967和0.938,均方根误差分别为0.112 m和0.107 m,表明GA-BP神经网络在近岸波浪模拟预报中有较广阔的应用前景.     

北仑河口潮流和余流特征分析

北仑河口水动力状况复杂,受入海径流、潮汐、波浪、沿岸流、风应力等多种因子的共同影响.对北仑河口S1、S2站长序列的海流剖面资料进行数学统计、潮流调和分析和数字滤波,探讨其潮流特征和余流形成机制.分析结果表明:北仑河口潮流性质主要为不规则全日潮流;观测期间S1站实测涨、落潮最大流速分别为39、83 cm/s,S2站分别为52、44 cm/s.研究海域余流流速从表层往底层逐渐减小,其中S1站余流流速主要介于5～10 cm/s之间,流向集中在S-SW向,S2站主要介于0～5 cm/s之间,表、中层以NNE-ENE向为主,底层以偏W向为主.风应力是调查区表层与近表层余流形成的主导因素;西向沿岸流对调查区的余流也有较明显的作用;径流对调查区的S1站有一定的影响,但对S2站影响很小;潮致余流对调查区的余流贡献较小.     

南堡油田保持中深层泥页岩井壁稳定钻井液研究

在南堡油田中深层钻井过程中,东二、东三、沙一段泥页岩的剥落掉块经常造成井壁坍塌掉块、钻具阻卡、电测遇阻等井下复杂情况。分析了中深层泥页岩的理化特性,研究探讨了泥页岩的坍塌机理。在此基础上,提出了选用强封堵抑制型钻井液是有效抑制中深层泥页岩剥落掉块的根本措施。这一研究成果对于在南堡油田中深层开发工程中提高钻速、减少井下复杂情况发生具有重要意义。     

鄂尔多斯盆地吴堡地区长6段浊积特征及其石油地质意义

在介绍鄂尔多斯盆地吴堡地区延长组长6段沉积特征的基础上,探讨了该储层物性特征、浊积岩特征、浊积岩分布规律及其对油藏的影响,明确了浊流沉积的石油地质意义.结果表明:鄂尔多斯盆地吴堡地区长6段以发育长石砂岩为主,填隙物成分有方解石、绿泥石、白云母以及少量的石英加大、长石加大等,砂岩储集层孔隙结构具有很强的非均质性;吴堡地区长6期湖盆沉降趋于稳定,是三角洲的高建设时期;多水系、多物源的三角洲前缘沉积为深湖浊积扇沉积提供了充足的物质基础;在吴堡地区东北部三角洲前缘水下分流河道前端发育深湖浊积扇沉积,可区分出中心微相和边缘微相两个沉积微相带,其中浊积扇中心微相以细砂岩、粉砂岩与暗色泥岩呈砂泥互层;从平面上看,浊积岩砂体非均质性在侧向上逐渐变弱,砂体底部发育厚度较大、成熟度较高的暗色湖相沉积的烃源岩,深湖相的暗色泥岩含有丰富的烃源岩,而浊积岩砂体是由深湖相的暗色泥岩构成,孔渗物性好的区域易于形成良好的上倾尖灭的透镜状岩性油藏.     

砂岩侵入体系模拟及形成机理分析

砂岩侵入体系是一种普遍的地质现象,近些年来越来越受到地学界的重视,但对其形成机理探讨较少。作者及研究团队通过设计一套室内模拟实验装置,来简化模拟3层地层结构中砂岩侵入体系的形成和演化过程。在之前模拟实验(实验变量为顶层沉积物的厚度、进水管的结构)结果的基础上,进一步考察了地形坡度对实验结果的影响,并对砂岩侵入体系的形成机理进行了分析。实验过程中,共观察到7种不同形态不同样式的管道,并对实验过程中压力变化进行了测试。对实验结果分析认为:盖层厚度越大,压力下降的速度越慢,越不利于压力的释放;随着实验的继续进行,砂岩侵入体最终会转化为砂岩喷出体并喷出地表;不稳定的地形有利于触发疏松沉积物发生变形。实验表明,超压是砂岩侵入体发生的最重要条件之一, 沉积盆地中的压实不均衡和生烃作用是可独立产生大规模超压的2种主要机制。     

Research Progress and Development Tendency About Thermal Physical Properties of Rocks

The fundamental researches about thermal physical properties of rocks have much concern in oil and gas field. They go through four stages and are applied in thermal structure of lithosphere, thermal evolution of sedimentary basins, geotechnical engineering and geothermal area. This article summarized the current research progress on the basis of thermal physical properties of rocks and proposed the development of tendency for the future. Moreover, some cylindrical heat pipe, disc heat pipe, spherical heat pipe based on in-situ measurement method and prediction model based on mathematical statistics have been developed. The scholars discuss the internal relation between thermal conductivity parameter of rocks and other physical properties by a large number of experiments. The researches show that the thermal conductivity of rocks is affected by many factors, and the petrologic characteristic is the most important factor. The porosity of rocks, filled fluid properties, acoustic characteristics are also related to thermal conductivity, which is affected by temperature, pressure and anisotropy. In consideration of the study of thermal physical properties of rocks, we proposed the following tendency for the future. First of all, shale gas is regarded as a hot spot in oil-gas exploration and the formation mechanism and the formation of shale gas reservoir are under the control of thermal physical properties of shale gas, but the relationship among thermal conductivity and organic porous, organic carbon content, gas content, fractured characteristics remains unknown. Therefore, exploring the thermal physical properties of gas-bearing shale is an important research direction in oil and gas field. Secondly, the study of big data represents the general trend. Though the database of rocks thermal parameter is continually expanding, measuring in-situ thermal conductivity continuously in well is the best method to get the accurate in-situ thermal conductivity of rocks. Hence, the development of logging method principle and logging instruments based on thermal physical properties of rocks is a necessary trend for the future.     

Experimental field assessment of suspended sediment pathways for characterizing hydraulic habitat

The distribution of particulate matter within river channels, including sediments, nutrients and pollutants, is fundamental to the survival of aquatic organisms. However, the interactions between flow and sediment transport at the patch scale of river systems represents an under‐researched component of physical habitat studies, particularly those concerning the characterization of ‘physical biotopes’ (riffles, runs, pools, glides). This paper describes a field methodology for exploring the transfer of particulate matter at small scales within river channels, which may be used to aid hydraulic habitat characterization. The field protocol combines field measurement of high frequency flow properties, to characterize hydraulic habitat units, and deployment of spatial arrays of turbidity probes, to detect the passage of artificially‐induced sediment plumes through different biotope units. Sediment plumes recorded by the probes are analysed quantitatively in the manner of the flood hydrograph, and qualitative inferences are made on the dominant mixing processes operating within different parts of the channel. Relationships between the nature of spatio‐temporal hydraulic variations within glide, riffle and pool biotopes, and the character and mixing behaviour of sediment plumes within these habitat units are identified. Results from these preliminary experiments suggest that investigating and characterizing the transfer and storage of sediments, nutrients and pollutants within and between different biotopes is a viable avenue for further research, with potential to contribute to improved physical habitat characterization for river management and habitat restoration. The experiments are also an illustration of the value of neglected synergies between process geomorphology, ecology and river hydraulics. Copyright © 2010 John Wiley & Sons, Ltd.     

地形变应变张量矩阵的不变量分析

在给出正交曲线坐标系的有关位移向量及其全微分、位移梯度矩阵、应变张量矩阵的普适表达式的基础上,又给出了任意两种正交曲线坐标系下的应变张量矩阵的普适转换表达式,并指出:由于该变换矩阵为正交矩阵,故应变张量矩阵为相似矩阵。并对应变张量矩阵的几何物理性质进行了分析,指出任何一种正交曲线坐标系的应变张量矩阵都具有唯一不变的主应变特征多项式,由该矩阵的主应变特征值方程皆可求得地壳质点处的主应变及其主方向,由主方向单位向量又可把该矩阵化为以主应变为对角元素的对角矩阵,该矩阵及其对角矩阵的迹皆为该质点处的体应变,该矩阵的行列式等于该质点处3个主应变的乘积,这些几何物理量皆为该质点处的地应变不变量。     

地域系统研究的开拓与发展

通过分析中科院地理科学与资源研究所地域系统研究的开拓与发展历程,总结了"综合自然区划-生态地理区域系统-综合区划"重要发展阶段的创新成果,介绍了重要的格局研究所取得的进展。地域系统研究与社会发展的客观需求密切相关。20世纪50年代,为了认识自然规律,为农业生产布局服务,开创了综合自然区划;20世纪90年代,从生态建设和环境保护的需求出发,将生态系统观点、生态学原理和方法引入地域系统研究,开展了生态地理地域系统研究;随着地球系统科学和可持续发展研究的深入,从20世纪末开始探索综合区划研究,自然要素和社会经济要素的有机融合成为近期格局研究的鲜明特色。在此过程中,地域系统研究的方法论和技术手段不断创新,遥感、地理信息系统和数值模型等的深入应用,极大地推进了该领域的研究。中科院地理资源所的地域系统研究,始终与国家的重大经济建设和环境保护紧密结合,成为今后自然地理学乃至地理学发展的一个重要方向。