基于波动方程的叠前地震反演          下载免费PDF全文

孙成禹  姚振岸  伍敦仕  喻志超 《地球物理学报》2019,62(2):604-618

随着地震勘探和开发的不断深入,面向地质目标的精细储层预测技术变得越来越重要.由于透射损失、层间多次波、波模式转换以及随机噪声等的影响,观测地震数据和待反演的地下介质属性之间呈现出很强的非线性.考虑到这些非线性,本文基于积分波动方程开展叠前地震反演,从观测地震数据中恢复出介质属性和整体波场,其中反演参数是波动方程中的压缩系数、剪切柔度和密度的对比度,相比于常规线性AVO反演的波阻抗弹性参数,它们对流体指示有更强的敏感性.在反演过程中,从平滑的低频背景场出发,交替迭代求解数据方程和目标方程.采用乘性正则化方法于共轭梯度框架下求解反演参数,采用优化的散射级数Neumann序列获得整体波场,这种方法不易陷入局部极值,能收敛到正确解.测井资料和典型山前带模型测试表明,利用上述反演方法能获得高分辨率的深度域地下介质属性,可直接进行储层预测和解释.  相似文献   

Effective application of automated digital photogrammetry for geomorphological research     

Jim Chandler 《地球表面变化过程与地形》1999,24(1):51-63

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Soil redistribution and pedologic transformations in coastal plain croplands     

Jonathan D. Phillips  Heather Golden  Karen Cappiella  Bain Andrews  Tamara Middleton  David Downer  Deonna Kelli  Lee Padrick 《地球表面变化过程与地形》1999,24(1):23-39

In agricultural basins of the southeastern coastal plain there are typically large disparities between upland soil erosion and sediment delivered to streams. This suggests that colluvial storage and redistribution of eroded soil within croplands is occurring, and/or that processes other than fluvial erosion are at work. This study used soil morphology and stratigraphy as an indicator of erosion and deposition processes in a watershed at Littlefield, North Carolina. Soil stratigraphy and morphology reflect the ways in which mass fluxes associated with cultivation transform the local soils. Fluvial, aeolian and tillage processes were all found to be active in the redistribution of soil. The soil transformations are of five general types. First, erosion and compaction in the cultivated area as a whole result in the thinning of Arenic and Grossarenic Paleudults and Paleaquults to form Arenic, Typic and Aquic Paleudults and Paleaquults. Second, redistribution of surficial material within the fields results in transitions between Arenic and Typic or Aquic subgroups as loamy sand A and E horizons are truncated or accreted. Third, aeolian deposition at forested field boundaries leads to the formation of compound soils with podzolized features. Fourth, sandy rill fan deposits at slope bases create cumulic soils distinct from the loamy sands of the source area or the darker, finer terrace soils buried by the fan deposits. Finally, tillage and fluvial deposition in upland depressions results in the gradual burial of Rains (poorly drained Typic Paleaquults) soils. Results confirm the importance of upland sediment storage and redistribution, and the role of tillage and aeolian processes as well as fluvial processes in the region. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

层状介质高频电磁场计算方法及结果分析   总被引：1，自引：1，他引：0       下载免费PDF全文

郑圣谈  曾昭发  张代国  王者江  姚健 《地球物理学进展》2007,22(6):1772-1776

本文在研究了高密度采样线性滤波算法计算层状介质高频电磁场的电磁响应的基础上,系统比较了Anderson等数值计算方法的速度和精度,给出了不同的地电参数和接收距对该计算方法精度的影响.通过比较表明,高密度采样算法不仅速度快,而且精度高.本文还对水平回线源层状介质当发射线圈位于地面时的表达式的第二项积分进行了公式推导,为电磁场的计算提供了清晰的思路.  相似文献   

加权总体最小二乘和RBF神经网络的三维坐标转换     

赵辉  郭春喜  孟静娟  耿晓燕  王文超 《大地测量与地球动力学》2023,43(1):29-33

分析部分变量误差加权总体最小二乘法（PWTLS）、加权总体最小二乘法（WTLS）和最小二乘法（LS）在三维坐标转换模型参数求解中的应用与影响,提出PWTLS与RBF神经网络组合的坐标转换方法。结果表明,当三维坐标转换模型系数矩阵中同时存在常数元素和重复元素时,PWTLS方法计算的单位权中误差和内符合精度均优于LS方法,且源坐标改正数较WTLS方法更加合理。PWTLS+RBF组合方法能够使PWTLS的求解参数得到有效使用,提高坐标转换精度。  相似文献   

Nonlinear Capillary-Gravity Waves Produced by a Vertically Oscillating Plate     

Philip L.-F.LIU 《中国海洋工程》1998,(2)

The nonlinear capillary-gravity wave produced by a vertically oscillating plate,in which thecontact-angle model is considered,is studied by use of the Boundary Integral Equation Method(BIEM).The present numerical experiment shows that the code is robust and efficient for modeling the generationand propagation of capillary-gravity waves.It is found that the wave heights of stationary periodicnonlinear waves radiated away from the plate are dependent on the parameters involved in the contact-an-gle model.The effect of the contact-angle hysteresis and the nonlinearity of capillary-gravity waves on thewave profile is discussed in the paper.  相似文献   

整体桥高性能混凝土桩−土相互作用试验研究     

黄福云  周志明  庄一舟  刘帆  刘名琦 《岩土力学》2022,43(3):591-601

高性能混凝土（高性能复合水泥基材料engineered cementitious composite,简称ECC与超高性能混凝土ultra-high performance concrete pile,简称UHPC）桩基具有良好的抗开裂性能和较高的承载能力,能较好地满足整体桥纵桥向变形。开展了砂土中高性能混凝土桩低周往复拟静力试验,得到了桩基的破坏特点、抗开裂能力以及极限承载力,分析了其桩身变形、桩侧土抗力以及桩身应变等分布规律,并与钢筋混凝土（RC）桩进行了比较。在此基础上,讨论了几种常用规范的适用性。试验结果表明,ECC、UHPC材料能有效减轻桩基的破坏程度、提高桩基的抗开裂能力以及水平承载力;相比RC桩基,高性能混凝土桩基的破坏位置更深,桩基的有效桩长更大,抗震性能更好;其中,ECC桩基的抗开裂能力最强,开裂荷载可达5.8 kN,开裂位移可达15 mm。试验结果还表明,高性能混凝土桩基的变形沿埋深方向不断的减小,埋深1.5 m以下位置基本为0;桩侧土抗力先增大后减小,桩底土抗力和变形量为0;桩身应变分布较为对称,且呈“橄榄”形,在埋深4D～6D（D为桩径）区间内桩身应变较大。分析计算表明,当桩顶位移在10 mm以内时,“m”法与API新规范法均能较好地计算高性能混凝土桩的桩身变形;当位移超过10 mm后,“m”法与实际数值相差较大。“m”法与API新规范法均不能较好地计算桩身弯矩,适用性不高;桩侧土抗力建议采用API新规范法。  相似文献   

祁连山西段党河流域地貌特征及其构造指示意义   总被引：1，自引：0，他引：1  

苏琦  袁道阳  谢虹  邵延秀 《第四纪研究》2015,35(1)

党河流域位于祁连山西段,流域内发育有三危山断裂、阿尔金断裂、野马河断裂和党河南山断裂等.这些断裂晚第四纪新活动性明显,控制着区内的构造变形、山体隆升与河流水系地貌发育.流域地貌参数指标能够很好地反映区域构造变形特征,因而党河流域地貌的发育和演化过程也记录了该区构造活动的重要信息.本文基于GIS空间分析技术,利用SRTM-DEM数据,系统提取了研究区内水系网络并对其进行Strahler分级后,获取党河流域各级亚流域盆地共计554个,进而计算了各亚流域盆地的面积-高程积分(HI)值,并对HI值进行空间插值,获取党河流域HI值空间分布特征.通过对比区内各个地貌参数指标,发现其与构造活动具有很好的相关性和同步性,表明构造活动对于流域地形地貌发育具有强烈的控制作用.区内亚流域盆地的面积-高程积分值分布特征表明,HI低值区与第四纪断陷盆地的范围相一致,而HI高值区则与晚更新世以来主干断裂的逆冲活动山体隆升范围相一致,反映了该区山体隆升和盆地沉降作用的总体面貌.  相似文献   

Slow Diffusion and Effective Stability of Dust Particles Orbiting Asteroids     

Harry Dankowicz 《Celestial Mechanics and Dynamical Astronomy》2002,84(1):1-25

This paper presents quantitative estimates of orbital lifetimes for small dust particles in the vicinity of a spherical asteroid orbiting the Sun on a circular orbit. In particular, the modeling accounts for gravitational interactions with the asteroid and the Sun and radiation pressure from the Sun. The analysis focuses on slow drift of particles in a state-space neighborhood of weakly unstable periodic orbits corresponding to the most tightly bound orbits about the asteroid. Through a Hamiltonian normal-form computation, Nekhoroshev-type estimates are derived that yield regions in state space of effective stability, that is, regions in which the grains would remain over significant periods of time in the absence of other depletion and replenishment mechanisms.  相似文献   

Studies of pre-main-sequence stars with integral field spectrographs     

Paulo J.V. Garcia 《New Astronomy Reviews》2006,49(10-12):590

We review the contribution of integral field spectroscopy (IFS) to pre-main-sequence star studies. These studies are mostly synoptic in nature reflecting the use of this technique in addressing difficult and complex objects. Physical diagnostics were derived from IFS data such as (atomic, molecular) gas excitation and pre-shock densities, gas morphology and spectra from close binaries. Models for the sources are directly tested: shock models (planar, bow-shock) and magneto-hydrodynamics jet models.Future contributions to the field are addressed. Surveys of mass loss across age and mass spectrum and in the nearby Orion Nebula cluster emerge as the most scientifically promising.  相似文献