波形选通器

一、引言在进行海洋爆炸声传播信号分析时,需要同时分析直达波和反射波。我们希望:在分析直达波时,需把反射波去掉;反之,分析反射波时需把直达波去掉。去掉反射波,可直接调整频谱分析仪的采样时间。(因反射波在后)而想去掉直达波,保留反射波,依靠调整采样时间就无能为力了。为此,研制了波形选通器,可方便地达到上述目的。二、方案的考虑1.输入门限电平的选择:由于声源距离及传播条件的影响,海上     

海洋水文多参数测量仪确定主波向的方法和应用

海洋水文多参数测量仪是南海海洋研究所新研制的一种可以同步测量海流、波浪、潮位、水温、电导率的仪器,利用同步观测压力和矢量流速估计海面方向谱的方法（PUV方法）可以计算得到海面方向谱,进而求得主波向。利用该仪器现场实测数据与荷兰MARKⅡ型“波浪骑士”方向浮标观测资料进行对比分析,表明两者的主波向吻合性好。     

挪威海畸形波波形特征研究

畸形波波形与其所处海况特征密切相关。在线性、窄谱假定下,最可能出现的畸形波波形服从“新波”理论,即最大波位于波群中间且其前后相邻波浪对称。然而,实际海浪谱通常是包含多种频率成分的宽谱。目前对实测畸形波及其附近波面形态特征仍缺乏系统认知,对其影响因素尚不明确。本文基于挪威海气象观测站共112个畸形波序列,分析实测畸形波波形及影响因素。研究表明,只有52%的畸形波在波群中间,其余畸形波在波群前侧的概率更高。此外,畸形波前后相邻波浪并不完全对称,其中位于后侧的波幅普遍更大。通过定量分析实测畸形波的平均波形与“新波”理论结果,发现谱宽是影响畸形波波形的关键参数。随谱宽增加,畸形波的平均波形与“新波”理论得到的波面序列误差呈指数增加。     

套管短口袋技术的应用探讨

介绍了短口袋技术可以提高固井质量及避免钻井掉块等优点,阐述了保证井身质量优良、井底少沉沙、套管长度与井眼深度的一致和套管居中等使用短口袋的技术要求.通过该技术在埕北古A井的应用,说明优选钻具组合和钻进参数,使用优质钻井液、通井和套管居中等技术措施可以满足要求,并成功地实现套管短口袋.     

套管井井间电阻率测井的原理及数值计算

本文以电磁场理论为基础 ,导出了过套管进行井间地层电阻率测井问题的理论公式 ,并用低频电磁波进行了数值计算 ,分析了套管对井间电阻率测井的影响。结果表明 :用低频电磁波过套管测量地层电阻率的井间测井方法是可行的。该理论可为套管井井间地层电阻率测井仪器的研制、测井解释及井间电阻率层析成像技术提供重要的理论依据。     

深水破碎波判据的研究──Ⅱ．一种风浪破碎判据的模式及实测结果分析

本文在讨论破碎波判据研究的基础上(文献[1]),根据前人的破碎波研究结果,以及海浪的随机性,建立了一个包含摩擦风速和波浪要素的破碎波判据计算模式,报告了在海上和实验室进行验证的实测结果.其特点是利用良好的现场观测条件和先进的实验设备,对破碎波进行了测量,首次通过划分破碎波的状态,合理地给出了破碎波判据的实测结果,并比较分析了其他几种波浪破碎判据的实测结果及使用范围.本文的计算风浪破碎判据的模式与外海实测结果比较接近,但与实验室测量结果相差较大.     

南黄海横波测井曲线预测在叠前反演中的应用

南黄海中—古生界发育大套碳酸盐岩和碎屑岩的互层沉积。为了满足油气地质勘探的需求,地球物理储层预测技术方法需要从叠后走向叠前阻抗反演,而横波速度是储层特征评价和流体识别的重要参数,因此,对该研究区进行横波测井曲线分析值得探索。基于实测的岩石物理弹性模量,通过Biot-Gassmann方程引进固结系数,将据此计算的纵波速度与实测的纵波速度进行对比,最终以其相对误差最小时的固结系数代入Biot-Gassmann方程求得横波速度,其预测结果符合地层速度的分布规律,并为叠前储层描述提供了可靠的基础资料。通过横波预测,石炭系灰岩段的纵波速度为5 500~6 500m/s,横波速度为3 000~3 200m/s,溶孔发育的白云质灰岩段纵横波速度比变化幅度大,碎屑岩孔隙发育地层横波速度变化幅度比纵波速度大。     

国产微电阻率扫描成像测井仪ERMI开发与应用效果

中海油新研制成功的增强型微电阻率扫描成像测井仪（ERMI）凭借独特的电路与机械技术优势能够适应各种不同复杂条件下的井眼环境,测得高质量的井壁电阻率图像。同时,ERMI配备了功能强大的地质解释软件,能够进行各种精细的数据处理,提供多种地质解释成果。通过在各种不同井况条件下的井眼测试,表明了ERMI具有良好的技术性能,且测得的图像清晰度与国际同类先进仪器的效果基本相当。自2011年12月以来,ERMI已经陆续投入到国内外的多个油田进行现场作业。     

反演一维声阻抗的Sondhi-Gopinath 法

作者从一维波动方程反问题的数学模型出发,经拉氏变换,根据Sondhi-Gopinath法,导出了分布参数系统一维声阻抗反问题的解析式.该解是一个称为脉冲响应参量的函数,它可由地面观测波场和位移速度来确定.     

汕头近岸区的台风波浪(三)各种重现期台风波浪要素的确定

本文以现场的实测资料和４４年间台风波浪后报结果为基础,考虑到各种重现期波浪出现时伴随着台风增水对计算点各种累积率波高的影响,通过对复合极值分布法,皮尔逊Ⅲ型曲线法和短期资料外推法的比较,给出进行波和破碎波条件下的各种重现期台风波浪要素。     

The role of the gravity-wave dispersion relation in HF radar measurements of the sea surface

Recent experimental and theoretical findings raise interesting questions about the applicability of the normal gravity-wave dispersion relation at wave frequencies that exceed the spectral peak frequency. The use of the dispersion relation in analysis of HF radar Doppler sea echo is examined in this paper. Drawing on the results of perturbation theory for wave-wave nonlinear interactions, we show that this relation, so essential to echo interpretation in terms of current and wave information, can be employed with no degradation in accuracy for current measurement when the dominant wave frequency is considerably less (by as much as 10) than the radar Bragg resonance frequency. This finding is supported by comparisons of currents measured by HF radar with "surface truth;" the first-order echo must only be identifiable in order to be used accurately. Wave-height directional spectral information can be extracted from the second-order echo at a given radar frequency up to the point (in wave height) where the perturbation solution employed in the inversion process fails; then a lower radar frequency must be used. On the other hand, most conventional wave measuring instruments should not use the dispersion relation for interpretation of data well beyond the spectral peak, because they do not observe wave height as a function of both space and time independently, as does HF radar.     

深水波中进动共振的数值模拟研究

进动(precession)共振是一种非线性共振相互作用,2016年才有学者对这一现象进行研究。采用非静压二维自由表面流模型模拟了深水条件下重力波的进动共振现象。通过边界造波的方法产生双色波,分析了触发进动共振的初始条件;探讨了进动共振在小振幅前提条件下发生的简化初始条件。数值模拟分析两组对称测点,对不同测点的波面、能量谱进行对比分析。数值结果表明:非静压二维自由表面流模型可以模拟进动共振现象,并且可以采用双色波作为条件来研究深水五波进动共振现象,进动共振需要一定的能量转化时间,进动共振发生的条件是三波组合的进动频率等于一个系统存在的非线性频率。     

Studies of backscattered sea return with a CW, dual-frequency,X-band radar

A coherent, CW, dual-frequency,X-band radar was used to study microwave sea return from the Chesapeake Bay. It is shown that the product of the backseattered fields depends strongly on long surface wave properties. In particular, a sharp line is found in the product power spectrum whose frequency is that of the water wave whose wavelength is in resonance with the spatial period of the beat frequency between the two transmitted signals and whose wave vector is parallel to the horizontal line of sight. Thus, gravity wave dispersion relations can be obtained with the system. Furthermore, the degree of modulation of short waves by long ones is given by the intensity of the line. A broad background corresponding to the convolution of the single-frequency Doppler spectra is also seen in the product power spectrum. These results are shown to be interpretable by composite surface scattering theory.     

X-波段雷达近海海浪频谱反演的神经网络模型

X-波段雷达作为国内海浪观测的一种新工具,在海浪频谱获取和有效波高反演方面仍存在较多问题.本文利用非线性回归方法,将现场实测浮标数据频谱和雷达一维图像谱分别与标准频谱模型进行拟合,发现浮标频谱和一维图像谱具有标准频谱的特征,能够较准确地获取相应的谱参数.提出了建立由雷达一维图像谱参数反演海浪频谱参数的神经网络模型,同时在模型中加入影像序列信噪比,进而反演有效波高,并将反演结果与现场实测数据和传统算法(建立影像序列信噪比与有效波高之间的线性回归方程)进行了对比,结果表明,获取谱参数的误差和反演有效波高的平均误差在20％以内,而传统算法计算有效波高平均误差在20％以上.     

Directional energy distribution of wind waves

Two-dimensional ocean wave spectrum developing under the atmospheric surface pressure fluctuations is linearly correlated with that of wind pressure itself, so that angular distribution of energy of ocean surface waves can be determined by directional properties of surface pressure fluctuations with the same frequency to the surface wave.From empirically determined spectral formula of the atmospheric surface pressure fluctuations the coefficients of Fourier series expanded around mean direction of wind are analytically integrated, from which r.m.s. angular distribution, spectral peakedness and long-crestedness are calculated, compared with previously proposed empirical formulae and observations carried out by ultrasonic current meter.     

Response-based estimation of sea state parameters — influence of filtering

Reliable estimation of the on-site sea state parameters is essential to decision support systems for safe navigation of ships. The wave spectrum can be estimated from procedures based on measured ship responses. The paper deals with two procedures—Bayesian Modelling and Parametric Modelling—which both use complex-valued frequency response functions (FRF) to estimate the wave spectrum. It is therefore interesting to investigate how the filtering aspect, introduced by FRF, affects the final outcome of the estimation procedures. In order to do this, extensive numerical simulations—with known wave parameters—are carried out for a large container vessel. The study shows that filtering has an influence on the estimations, since high-frequency components of the wave excitations are not estimated as accurately as lower frequency components.     

The form of the asymptotic depth-limited wind-wave spectrum: Part II — The wavenumber spectrum

Data from a spatial array of wave gauges is analysed using the Wavelet Directional Method (WDM) to directly determine the wavenumber spectrum. The data shows that the asymptotic depth-limited wavenumber spectrum can be represented as a two-parameter form, which is far simpler than the corresponding frequency spectrum. The WDM analysis shows that there are significant nonlinear processes active in the finite depth water, which results in energy being “smeared” across a range of wavenumbers and frequencies around the standard dispersion shell. As a result, the wavenumber spectrum has much less peak enhancement than seen in the frequency spectrum obtained with standard Fourier analysis. In addition, the wavenumber spectrum does not have the clear harmonic previously observed in the finite depth frequency spectrum. This result demonstrates that the harmonic is nonlinearly phase-locked to the spectral peak.     

地震反演和分频技术在深水油气勘探中的应用

对于深水沉积盆地,由于高投入、高风险、高技术因素,有些区域内勘探程度低或无钻井,在此条件下如何更好地寻找有利区带,提高勘探成功率是最迫切的问题。为此,运用无井反演和地震分频技术对西非某深水盆地进行了研究。地震分频技术实现了在频率域内通过调谐振幅属性的对应关系来研究储层横向变化规律,经分频处理后的地震数据其解释分辨率高于常规地震主频所能达到的分辨能力,有利于确定含油气储集层边界、估算地层厚度。在无井地区开展波阻抗反演,和地震分频技术结果进行相互印证,预测了西非某深水盆地有利相带和储层的发育区带。     

海浪外观统计与内部结构关系的数值研究

基于数值模拟的三维随机海面,从时间域和空间域两个角度对海浪的外观特征和内部结构间的关系进行了研究,得出了一些在工程应用上有参考价值的结果.文章认为,将波面看作是若干随机正弦波叠加的海浪结构模型,用于描述平稳、均匀和窄谱的海况时,其频谱分析结果与外观统计结果基本上是一致的;但是,当海面处于谱宽度较大的风浪或混合浪状态时,一些频谱分析结果必须经过修正才能应用.同一海况下,海面波动的时间过程和沿主波向的空间分布是明显不同的.当海面有突发性大浪时,外频谱能够很好地反映不平稳海况,而频谱则把这种不平稳性平滑了.文章着重讨论了波长和波陡的计算、频谱和外频谱的差异.