横波测井技术在海洋工程中的应用     

白大鹏  赵铁虎  顾雪晴  宋宝顺 《物探与化探》2011,35(3):409-413

单孔波速测试的传统做法是在地面激振,在孔中接收,但该方法测试深度受限,测试精度较低,且对于海上钻孔来说,根本无法实现激振,故对于海洋工程钻孔的波速测试,则需要新技术来实现横波波速的获取。笔者介绍的悬挂式波速测井法将震源和检波器同时放入井孔中,摆脱了笨重的地面敲击震源,实现了波速测井设备的轻便化,由相距1 m的两个检波器接收S波的传播信号,为一发双收装置,利用传感器接收到震源传来的S波信号到达时间(初至)差,来确定钻孔所在处地层波速的一种新技术。该方法在南堡油田平台场址调查中发挥了重要作用,对120 m深的钻孔进行了横波测井,取得了良好的测试成果,为该工程项目提供了准确的剪切波速,为划分该场址的场地土类别发挥了重要作用。  相似文献   

基于大炮初至的近地表层析反演方法研究及应用   总被引：1，自引：0，他引：1  

杨晶  徐维秀  宋建国 《物探与化探》2011,35(4):499-504

详细研究了射线追踪、层析反演方法原理以及层析反演数值求解算法,提出了利用大炮初至直接建立初始地震模型,由小折射和微测井进行约束的层析反演近地表速度模型的处理流程,提出了基于多次回溯的高精度快速射线追踪算法和层析反演数值求解算法。采用双重网格技术提高正演模拟计算精度和层析反演的成像质量,另外,充分考虑多种质量控制方案,确保最终的反演速度模型精确。设计了10种不同地表地质条件的理论模型,进行模型试算,并在实际生产中应用,理论模型试算和实际资料反演结果证明了本文方法的正确性。  相似文献   

非对称走时克希霍夫叠前时间偏移方法在塔河地区的应用     

姜大建  宇俊瑞  张改兰  李燕 《物探与化探》2011,35(5):643-647

针对塔河油田"复式"成藏组合所具有的油气圈闭类型复杂、储层厚度薄、构造幅度小、岩性横向变化大和非均质性强等特点,采用非对称走时克希霍夫叠前时间偏移方法进行数据处理。与常规叠后时间偏移和弯曲射线克希霍夫叠前时间偏移相比,非对称走时克希霍夫叠前时间偏移成果剖面绕射波归位合理,断层、断点清晰,不整合面成像及奥陶系内幕碳酸盐缝洞体反射结构更加清楚,横向分辨率进一步提高。  相似文献   

A Kinematic Thermal Model for Descending Slabs with Velocity Boundary Layers: A Case Study for the Tonga Subducting Slab   总被引：3，自引：0，他引：3  

ZHANG Keliang an  WEI Dongping 《《地质学报》英文版》2011,85(1):211-222

For the purpose of investigating the influence of metastable olivine (MO) phase transformations on both deep seismicity and stagnation of slabs, we constructed a 2-dimensional finite element thermal model for a 120 Ma-old 50o dipping oceanic lithosphere descending at 10 cm/yr with velocity boundary layers, which would mitigate the interference of constant velocity field for the slab. The resulting temperatures show that most of intermediate and deep earthquakes occurring within the Tonga slab are occurring inside the 800oC and 1200oC isotherm, respectively. The elevation of olivine transformation near ~410 km and respective persistence of metastable olivine and spinel within the transition zone and beneath 660 km would thus result in bimodal positive, zonal, negative density anomalies, respectively. These results together with the resulting pressure anomalies may reflect the stress pattern of the Tonga slab: (i) slab pull force exerts above a depth of ~230 km; (ii) MO existence changes the buoyancy force within the transition zone and facilitates slab stagnation at a depth of 660 km; (iii) as the subducting materials accumulated over 660 km, deepest earthquakes occur due to MO transformation; (iv) a flattened ‘slab’ may penetrate into the lower mantle due to the density increment of Sp transformation.  相似文献   

Rayleigh面波各阶模式频散曲线对横波速度和层厚的敏感性探讨   总被引：1，自引：1，他引：0  

张明财  熊章强  张大洲  刘白璐 《物探化探计算技术》2011,33(2):153-158

Rayleigh面波勘探的目的在于有效利用频散曲线反演地层厚度及横波速度,而不同模式的频散曲线对横波速度和层厚的敏感性不同。通过求取介质参数变化10%后与参数不变化时的二组频散曲线的差值,得到各阶模式的频率～相速度差曲线,分析了Rayleigh面波各模式频散曲线对横波速度、层厚的敏感性。试验结果表明,基阶模式对于浅层的横波速度和层厚比较敏感,敏感区域主要集中在较窄的频带范围内。而高阶模式对于相对较深层的横波速度和层厚比较敏感,且频率范围分布较大,敏感性强的频段分布比较分散。研究结果可以为Rayleigh面波多模式联合反演提供理论依据。  相似文献   

辽河盆地东部凸起区二叠系层速度-砂地比定量解释          下载免费PDF全文

严恒  代宗仰  王丽君 《江苏地质》2011,35(4):366-368

辽河盆地东部凸起勘探程度较低,钻井资料较缺乏,但地震资料相对较丰富。为了能在有限的资料中发掘更多能反映二叠系砂岩分布情况的信息,借助于地震处理中的速度分析资料,利用层速度-砂地比定量解释模型得到二叠系砂地比分布图,并在此基础上对二叠系的有利勘探区带进行了预测。  相似文献   

Propagation of water waves over permeable rippled beds     

Ching-Jer Huang  Chih-Hsin Chen 《Ocean Engineering》2011,38(4):579-591

Unsteady two-dimensional Navier-Stokes equations and Navier-Stokes type model equations for porous flow were solved numerically to simulate the propagation of water waves over a permeable rippled bed. A boundary-fitted coordinate system was adopted to make the computational meshes consistent with the rippled bed. The accuracy of the numerical scheme was confirmed by comparing the numerical results concerning the spatial distribution of wave amplitudes over impermeable and permeable rippled beds with the analytical solutions. For periodic incident waves, the flow field over the wavy wall is discussed in terms of the steady Eulerian streaming velocity. The trajectories of the fluid particles that are initially located close to the ripples were also determined. One of the main results herein is that under the action of periodic water waves, fluid particles on an impermeable rippled bed initially moved back and forth around the ripple crest, with increasing vertical distance from the rippled wall. After one or two wave periods, they are then lifted towards the next ripple crest. All of the marked particles on a permeable rippled bed were shifted onshore with a much larger displacement than those on an impermeable bed. Finally, the flow fields and the particle motions close to impermeable and permeable beds induced by a solitary wave are elucidated.  相似文献   

Numerical modeling of hyperpycnal flows in an idealized river mouth     

Yan Wang  Houjie Wang  Naishuang Bi  Zuosheng Yang 《Estuarine, Coastal and Shelf Science》2011

Numerical experiments in an idealized river mouth are conducted using a three-dimensional hydrodynamics model (EFDC model) to examine the impacts of suspended sediment concentration (SSC), settling velocity of sediment and tidal mixing on the formation and maintenance of estuarine hyperpycnal flows. The standard experiment presents an illustrative view of hyperpycnal flows that carry high-concentrated sediment and low-salinity water in the bottom layer (>1.0 m in thickness) along the subaqueous slope. The structure and intra-tidal variation of the simulated hyperpycnal flows are quite similar to those previously observed off the Huanghe (Yellow River) mouth. Results from the three control experiments show that SSC of river effluents is the most important parameter to the formation of hyperpycnal flows. High SSC will increase the bulk density of river effluents and thus offset the density difference between freshwater and seawater. Low SSC of river effluents will produce a surface river plume, as commonly observed in most large estuaries. Both the settling velocity of sediment particles and the tidal mixing play an important role in maintaining the hyperpycnal flows. Increasing settling velocity enhances the deposition of sediment from the hyperpycnal layer and thus accelerates the attenuation of hyperpycnal flows, whereas increasing tidal mixing destroys the stratification of water column and therefore makes the hyperpycnal flows less evident. Our results from numerical experiments are of importance to understand the initiation and maintenance of hyperpycnal flows in estuaries and provide a reference to the rapidly decaying hyperpycnal flows off the Huanghe river mouth due to climatic and anthropogenic forcing over the past several decades.  相似文献   

0903号台风“莲花”的风结构分析     

张加春  饶灶鑫  陈煜  蔡巧晖 《台湾海峡》2011,30(4):507-511

通过对0903号台风“莲花”在登陆福建晋江并沿着海岸线北上过程中的沿海自动站逐时实况风场资料的分析,研究了该台风的风结构状况,得到以下结论：（1）台风近中心最大风速预报值比实测风速偏小,台风7级风半径则比实际的偏大．（2）实测2min平均风速最大值（Vmax）总体上呈减弱趋势,与时间（t）的回归方程式为：Vmax=28．9—0．61t（n=16,r=0．78,r005=0．50）．（3）台风最大风速半径（R）呈逐渐扩大的趋势,与时间（t）的回归方程式为：R=28．28—4．98t＋0．67t。（n=16,r=0．95,r0.05=0．50）．（4）台风最大风速区位于台风后部．认识台风风结构,有助于不断地提高预报的准确性．  相似文献   

声学法深海热液速度场测量重建算法研究   总被引：1，自引：1，他引：0       下载免费PDF全文

白燕  毛洁  樊炜  潘华辰  刘云峰 《海洋科学》2011,35(3):42-49

介绍了利用声学法测量深海热液速度场的基本原理.利用往返飞渡时间差与流场速度的关系,应用反问题求解技术重建测量区域的速度场.应用最小二乘法对两种典型的热液口速度场模型进行了仿真重建,分析了换能器数量、实验测量误差以及换能器的布放对重建结果的影响,并对重建结果进行了流量分析.仿真重建的绝对误差、相对误差以及流量分析结果表明...  相似文献