Modeling of the Changes in Flow Velocity on Seawalls under Different Conditions Using FLOW-3D Software

Seawalls are among protective structures that are constructed for decreasing the level of wave force and/or protecting from other structures. In this regard, more accurate investigation of these structures takes great importance from different perspectives. This research investigates the change of the velocity on seawall crown by considering the obstacles in different layouts and slopes. FLOW-3D has been used in this research for modeling. The results of the modeling show that the existence of obstacles has a determinative role in decreasing flow rate in the crown of seawalls. Also, as it was expected, the slope factor on upstream seawalls is very determinative in decreasing this rate such that the lowest velocity on the wall occurs in D-state layout and the slope of 45°.

Velocity and Structural Modeling of Mesozoic Chiltan Limestone and Goru Formation for Hydrocarbon Evaluation in the Bitrisim Area, Lower Indus Basin, Pakistan

The present study focuses on building a workflow for structural interpretation and velocity modeling and implementing to Jurassic-Cretaceous succession （Chiltan Limestone and Massive sand of the Lower Goru Formation）. 2D-Migrated seismic sections of the area are used as data set and in order to confirm the presence of hydrocarbons in the study area, P and S-wave seismic velocities are estimated from single-component seismic data. Some specific issues in the use of seismic data for modeling and hydrocarbon evaluation need to deal with including distinguishing the reservoir and cap rocks, and the effects of faults, folds and presence of hydrocarbons on these rocks. This study has carried out the structural interpretation and modeling of the seismic data for the identification of traps. The results demonstrate existence of appropriate structural traps in the form of horst and grabens in the area. 2D and 3D velocity modeling of the horizons indicates the presence of high velocity zones in the eastern half of the study while relatively low velocity zones are encountered in the western half of the area. Two wells were drilled in the study area （i.e. Fateh-01 and Ichhri-01） and both are dry. Immature hydrocarbons migration is considered as a failure reason for Fateh-01 and Ichhri-01 well.

Three-dimensional P-wave velocity structure of the crust beneath Hainan Island and its adjacent regions,China

Using over 3 500 first P arrival times recorded by nine digital seismic stations from Hainan Digital Seismic Net-work during 1999～2005,a 3-D P-wave velocity model of the crust under Hainan Island and adjacent regions has been determined. The results show that the pattern of velocity anomalies in the shallower upper crust is somewhat associated with the surface geological tectonics in the region. A relative low-velocity anomaly appears north of the Wangwu-Wenjiao fault zone and a relative high-velocity anomaly appears south of the Wangwu-Wenjiao fault zone,corresponding to the depressed areas in north Hainan Island,where many volcanoes are frequently active and geothermal values are relatively higher,and the uplifted and stable regions in central and south of the Hainan Is-land. In the middle and lower crust velocities are relatively lower in east Hainan than those in west Hainan,possi-bly suggesting the existence of the upwelling of hot materials from the mantle in east Hainan. The pattern of veloc-ity anomalies also indicates that NW faults,i.e.,the Puqian-Qinglan fault,may be shallower,while the E-W Wangwu-Wenjiao fault may be deeper,which perhaps extends down to Moho depth or deeper.

Sensitivity of Lagrangian Particle Tracking Based on a 3D Numerical Model

The aim of the paper is to investigate in detail the sensitivity of particles displacement based on method of Lagrangian particle tracking in combination with a 3D Eulerian numerical model that was developed by the first author, namely FSUM. The characteristic parameters used for this research include the possibilities of random movement, settling velocity of solid particle, horizontal and vertical diffusion coefficients and condition of particle fixed with a constant distance under water surface. The first part is on the fluid flow model. It includes 3D Navier-Stokes equations together with the initial and boundary conditions that were numerically solved with the finite difference method and coded with FORTRAN 90/95 using parallel technique with OpenMP. A semi-Lagrangian treatment of the advective terms was used. The second part is related to Lagrangian particle tracking model and was solved with the fourth Runge-Kutta method. Model was applied for Strait of Johor and has been calibrated by using measured data on water level and velocity at one station. Eight cases of simulations with many different options were carried out. Through computed cases it shows that random term and settling velocity are very important factors for the behavior of particle trajectory. Although the random diffusion is minor in comparison with flow velocity, but it can rearrange the initial distribution of particles then the cluster of particles become more dispersive during the process of movement. In addition, introducing settling velocity of particle makes a big change on the trajectory of particle that becomes more suitable to sediment transport. The study gave a comprehensive picture on particle movement. The model also showed its possibilities of multiform applications in simulation and prediction for the different problems in practice.

Quasi-3D Numerical Simulation of Tidal Hydrodynamic Field

Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.

SIRIUS3D叠前深度偏移软件在BZ25—1构造上的应用

介绍了SIRIUS3D叠前深度偏移软件的技术特点及工作流程,分析了该软件的优点和不足.将该软件首次应用于BZ25-1构造,通过精细的速度反演,建立了较为准确的三维速度模型,最终叠前深度偏移结果较为理想,尤其是中浅层复杂断层的成像质量得到明显提高,为BZ25-1构造评价提供了重要依据.

3D S-Wave Velocity Structure of the Crust and Upper Mantle

In this paper, 238 Rayleigh wave path data are selected and processed by the matched-filtering frequency-time analysis technique and the grid dispersion inversion method to obtain the 3D S-wave velocity structure of China mainland and its adjacent sea regions. The results show that the velocity structure relates to geotectonic division, Bouguer gravity anomaly is basically controlled by the relief of Moho discontinuity, the buried depth of LVL in upper mantle concerns the surface heat flow deeply. In this paper, authors indicate the main characteristics of the velocity structure in tectonic active and stable regions.

三维叠前时间偏移技术在江苏WZD地区的应用

当地下地质构造复杂、断裂发育,横向速度变化不是太剧烈的情况下,提高偏移成像精度,三维叠前时间偏移是一种行之有效的方法。三维叠前时间偏移取得成功的关键:一是高保真、高信噪比的叠前数据;二是建立一个合理的三维偏移速度场。随着计算机性能的不断提高,三维叠前时间偏移逐渐成为常规处理技术,该技术在江苏油田WZD地区得到了广泛的应用,实际资料处理结果及钻探效果证实了三维叠前时间偏移技术是解决WZD地区复杂构造成像精度的一种好方法。

CRUST AND UPPER STRUCTURE OF QINGHAI-TIBET PLATEAU AND ITS ADJACENT REGIONS FROM SURFACE WAVEFORM INVERSION

In this paper,218 long period Rayleigh wave records from 7 seismic station of CDSN are selected.We applied a partitioned waveform inversion to these data in order to construct a 3\|D model of shear velocity down to 400km depth in the crust and upper mantle of Qinghai\|Tibet plateau and Its Adjacent Regions (22°～44°N,70°～110°E).The first step of the waveform inversion used involved the matching of the waveforms of fundamental and highermost Ravleigh waves with waveforms synthesized from stratified models;in the second stage,the 3\|D model was constructed by solve linear constrains equation. The major structural features inferred from the surface waveform inversions can be summarized as follows:(1) There is a great contrast between surface waveform through Qinghai—Thibet plateau and the others.Main frequency of the former is lower than the latter, which indicate the crust depth of Qinghai—Tibet plateau is deeper than the others. In addition,the amplitude of about 30s period and 50s period is lower than both sides,which implied these exist lower velocity layer at about 25km depth and about 50km depth in Qinghai—Tibet plateau Crust.The former is common,the latter was argued because resolution of most method can not prove it.

Numerical Study of the Dynamic, Thermodynamic and Microstructural Parameters of Convective Clouds

On the basis of a three-dimensional non stationary model of a convective cloud with detailed description of dynamic, thermodynamic and microphysical processes, numerical experiments were conducted to study the formation of parameters of convective clouds under unstable stratification of the atmosphere. Numerical experiments have been carried out to study the formation of convective processes in the atmosphere. The thermo hydrodynamic parameters in the zone of a thunderstorm cloud are determined, and regions with a vortex motion of air are identified. The main flows feeding the convective cloud in the mature stage are determined. Due to the means of visualization, the areas of formation and growth of precipitation particles are identified. In a three-dimensional form, the interaction of dynamic and thermodynamic processes is analyzed. The interaction of fields is manifested in the form of deformation of fields of thermodynamic parameters under the influence of dynamic processes. Trajectories of air streams around a cloud and the trajectories of drops in a cloud are determined. The results of numerical experiments confirm that dynamic processes significantly influence the formation of fields of thermodynamic parameters in the cloud, which also determine the course of microphysical processes and the nature of the growth of precipitation particles.

2019年长宁M_(s)6.0地震周边区域速度与P波各向异性成像研究

利用基于程函方程求解的地震走时层析成像方法对2019年长宁M_(s)6.0地震震中及其周边区域进行反演成像,获得了该区域高分辨率三维P波、S波速度结构以及P波方位角各向异性参数分布,并对几个典型剖面的泊松比结构进行了分析。结果表明,方位角各向异性对地震波P波走时具有显著的影响;研究区域上地壳速度结构存在显著的非均匀性,且一些相对低速异常与注水采盐、天然气水力压裂开采及废水回注等工业活动区域具有明显的对应关系,显示人类的工业活动可能已经对上地壳的物质性质产生了影响。长宁地震的发生可能由注水采盐活动直接诱发,而由工业活动所造成的速度异常结构对区域内地震的发生可能产生的影响是持续性的。区域内P波方位角各向异性可能受板块运动和主压应力影响,而长宁地震序列震源区域浅层P波方位角各向异性以近EW向为主,与该区域的主压应力方向基本一致。这些结果为认识四川盆地东南缘精细地壳结构、深部物质运动和动力学机制提供了新的资料。

巴楚夏河工区的三维速度建模方法

本文结合巴楚夏河工区的实际情况,详细探讨了该区三维速度建模方法。此法以地震速度平衡建模思想为指导,以随机模拟法为基础,采用离散平滑插值技术构建三维离散空间建模。与其他建模方法相比,此法的建模步骤及应用效果具有以下优点:1采用由点到面到体的建模过程,充分细致地反映了三维空间离散结构;2在建模过程中提供了大量插值、数值模拟方法,保证了建模的可靠性;3充分利用测井与地震信息,保证了建模的准确性;4所求速度模型能准确反映速度空间变化规律。文中具体介绍了建模步骤。在巴楚夏河地区的应用结果表明,此法能够较好地解决地震资料处理与解释中的速度问题,尤其是复杂地区的速度问题,可为油气田勘探开发提供准确的速度资料。

云内大粒子对闪电活动影响的个例模拟

利用三维云起电放电模式,通过对2008年9月6日北京地区一次雷暴过程的模拟,研究了云内雨滴、冰晶、霰和雹4种粒子对云内闪电活动的直接影响。对比几种主要冰相粒子比质量浓度的分布变化与模拟闪电开始发生高度的关系,并分析几种冰相粒子所带电量变化率的时空变化特征后发现:霰和冰晶是对云内闪电发生作用最为重要的两种粒子;雹粒子对闪电发生作用有限;雨滴则对于主电荷区附近闪电发生没有直接影响。模拟结果表明:在实际观测中出现的雷达强回波达到某个高度之上可以预警闪电发生的现象,主要是由于霰粒子在一定高度之上与冰晶之间发生强烈的电荷分离,从而使云内电场迅速增强,并最终引发闪电而导致的。

南阳凹陷高精度三维地震采集观测系统设计

南阳凹陷主要勘探目的层埋藏较深,断裂发育、构造破碎,现有地震资料的信噪比和分辨率不能满足油气勘探需求。为此,针对南阳凹陷的地震地质条件,结合地震波动方程模拟、照明分析以及观测系统采集脚印分析等技术,在兼顾各项采集设计要求与工作效率的条件下,重新设计了三维地震观测系统。实际应用结果表明,采用上述观测方法获得的地震资料质量较原资料有明显的改善。新采集的资料剖面断裂系统成像清晰,目的层及其以上各反射层特征清楚,分辨率和信噪比均有较大的提高。

一种新的三维速度结构反演模型参数化方法

本文针对三维速度反演问题中的一个重要步骤——模型的参数化作了探讨和研究,提出了一种新的参数化方法.同以往采用的矩形分块或划分网格点的方法不同,将待求扰动场按其空间频率展开,反演各阶频率系数.从三维傅氏级数理论出发,导出了一个简明且便于计算的三维空间频谱展开公式,并从理论上分析了在空间域内离散模型和空间频率域内离散模型的不同之处. 理论分析表明,在空间域内采用过参数化离散模型来反演,会在所得到的解中混入人为的虚假结构,从而使反演解发生畸变.采用在频率域内离散模型的频谱参数化方法反演,可以有效地避免这一点.频谱参数化方法也使得我们可以过参数化(over-parameterization)离散模型,便于最大程度地从资料中提取正确信息,对模型的分辨程度完全取决于观测系统的分辨能力.这种方法在得到稳定的反演解的同时,还可得到观测系统在空间三个方向上的分辨率.数值模拟实验结果证实了以上结论.

水平方管内固液两相流运动特性数值模拟

将周力行建立的k-ε-kp两相湍流模型引入固液两相流的研究中,对水平方管内挟沙水流固液两相的时均特性、脉动特性以及颗粒密度分布进行了数值模拟。将计算结果与k-ε-Ap模型、动理论计算结果以及物理模型试验观测结果进行了比较,发现k-ε-kp模型数值计算和物理模型试验观测结果的一致性较好;和k-ε-Ap模型相比,由于考虑了颗粒相的湍动特性在固液两相流中的作用,k-ε-kp两相湍流模型可以得到颗粒的脉动速度分布;和动理论相比,k-ε-kp模型无法准确地预测固相的垂向脉动速度,需要引入各向异性的两相流模型。

三维叠前时间偏移技术在江苏高邮凹陷的应用

当地下地质构造复杂、断裂发育,横向速度变化不太剧烈的情况下,三维叠前时间偏移是一种提高偏移成像精度的行之有效的方法。三维叠前时间偏移取得成功除了有一套高保真、高信噪比的叠前数据之外,还须建立一个合理的三维偏移速度场。通过对江苏油田高邮地区实际三维地震资料处理,解决了叠后时间偏移无法查清的复杂断块的成像以及火成岩岩下目标层的成像问题。钻探结果与处理结果相吻合,证实了三维叠前时间偏移技术是解决高邮地区复杂构造成像的一种好方法。

先验信息约束层析成像静校正技术在柴西南地区的应用

在柴达木盆地西部南区,针对不同的地质目标采集了多块三维地震资料,对于该地区进一步的油气勘探开发,需要整体认识该区域的地质特征和沉积相,为此在该区开展了三维地震资料连片处理研究。柴西南地区近地表结构复杂,岩性多变,地表高差达600 m,低、降速层厚度变化大(4～200 m),连片处理中静校正问题突出。在对各种静校正方法适应性分析的基础上,提出了先验信息约束层析成像静校正技术,阐述了该方法的基本原理和实现步骤。在方法实现时,区块之间的初至时差采用相关法予以消除,初始速度模型采用相控处理的小折射和微测井资料来建立,并将该模型作为初至波非线性层析反演的约束条件,建立了准确的近地表速度模型,计算全区的静校正量。应用效果分析表明,先验信息约束层析成像静校正技术可以较好地解决复杂地区三维地震资料连片处理中的静校正问题。

地震物理模型中三维地质模型材料特性研究

实际地质构造具有复杂和岩层速度变化大等特点,制作相应的三维地质模型,需要有各种性质的模型材料,以满足模型与实际情况相接近的要求。为此,对几种模型材料的性质和适用范围进行了分析。一般工业材料的速度,虽然有些能与岩石速度相匹配,但却难以加工成各种各样的构造形态,而且不能满足对层与层之间胶合质量的要求。环氧树脂和合成橡胶是工业上常用的2种材料,具有液态固化特性,将两者混合在一起可得到速度连续可变的混合材料。实验表明,混合材料中硅橡胶与环氧树脂的量之比(配比ε)不同,速度可在2600～950 m/s之间变化。变化规律呈现出3种方式：配比ε在0～50%之间,混合材料的速度随硅橡胶量的增加线性降低；配比ε在60%～100%之间,速度下降的趋势变缓,速度的变化主要取决于硅橡胶的速度；配比ε在50%～60%之间,混合材料的速度范围为1350～1800 m/s,在此范围,速度受温度的影响较大,出现了不稳定现象,用柔性环氧树脂可以消除这种现象。此外,硅橡胶量多的混合材料,对横波的传播不利。利用混合材料的液态固化特性,可以根据需要,利用模具技术制作各种形态的地质构造模型,且层与层之间的胶合性质与实际地层沉积特性相似。