波形反演遗传算法及其在地震测深数据解释中的应用

为了更好地利用地震测深波形数据,提出了地震体波波形反演的遗传算法. 正演使用能精确快速计算互层结构响应的广义反、透射系数理论地震图算法;反演采用遗传算法,实现了地震体波波形反演的遗传算法. 数值试验表明,该算法具有分辨壳内低速层、高低速薄互层结构和一定的抗噪能力. 青藏高原东北缘泽库、夏河、临洮3炮地震测深P波波形反演,得到了上地壳底部低速层和中、下地壳,以及上地幔顶部薄互层的细结构图象.      

基于高分辨率瞬时信息与相干算法的低幅度构造识别

随着勘探程度的深入,隐蔽圈闭,尤其是低幅度构造油气藏逐渐受到关注,其在地震资料上表现为反射同相轴平直且变化幅度很小,不易识别.利用相干算法识别低幅度构造,确定出了薄互层低幅度构造的空间展布;经过高分辨率复数道分析处理,提高了剖面分辨率,利用高分辨率瞬时振幅、相位、频率剖面的各自特性识别出了薄互层低幅度构造的构造异常点,此基础上再结合相干算法识别低幅度构造,精度更高.     

基于同步挤压小波变换的煤层强振幅抑制

在油气地震勘探中,有些含油气目标层临近煤层,会受到煤层强振幅的影响,导致储层在地震剖面的响应难以识别,地球物理参数计算不准确.为此,本文设计了基于同步挤压小波变换(Synchrosqueezed Wavelet Transform,SWT)的煤层强振幅抑制方法.利用SWT高分辨率、高精确度的时频特性准确地筛选出煤层强振幅部分,根据能量关系进行抑制,并保留其他信息,最后通过重构实现煤层强振幅抑制算法.通过对模型数据和苏里格地区实际地震数据的处理,结果表明该方法不仅能够有效地抑制煤层强振幅,且在精细程度和准确度上优于基于经验模态分解的煤层强振幅抑制方法.     

煤层冲刷带地震响应特征及其与煤层瓦斯突出的相关性分析

阳泉新景煤矿生产实践发现3#煤层发生的煤与瓦斯突出事故大部分位于煤层冲刷带.三维地震勘探记录地层连续性好、控制精度高,是识别煤层冲刷带最常用的技术手段.本文以新景矿芦南二区为研究区,建立二维正演模型,研究煤层的地震响应规律,发现其振幅和相位属性对煤层冲刷带响应明显.利用该区现有的三维地震资料,综合瞬时振幅属性特征、地震相分类特征及声波阻抗响应特征,圈定冲刷带平面位置及分布范围.运用有限元分析软件对煤层冲刷带应力分布进行三维正演模拟,结合煤样测试结果,对区内应力异常带的煤层瓦斯和煤体结构等进行分析.研究发现煤层冲刷带过渡区段突出危险性最大,是圈定冲刷带的关键部位,研究成果与实际突(喷)出点位置吻合度较高.总之:1)煤层冲刷作用是导致瓦斯地质条件差异性的主要因素之一,过渡区段为重点防突区域;2)综合多种地震岩性信息响应特征在准确识别煤层冲刷带位置及分布范围方面效果显著.     

基于地震属性的煤层厚度预测模型及其应用

地震属性技术在岩性和构造解释等方面得到了越来越广泛的应用,特别是在煤、油气资源勘探中具有重要的作用.基于淮南矿区谢桥1区13 1煤层地震勘探资料,提取了28种地震属性数据;通过地震属性的分析,优选出平均峰值振幅、振幅的峰态、最大绝对振幅、瞬时频率斜率等4种地震属性作为煤层厚度预测模型基本参数,结合已知钻孔资料,利用多元多项式回归以及BP人工神经网络方法,求出了各属性与煤厚之间的多元多项式回归模型及人工神经网络模型,并对模型进行了误差分析和应用结果对比分析,反映出人工神经网络模型在煤厚预测中具有好的应用效果.     

宽频地震数据瞬时振幅属性优势分析及在南海深水区的应用

在过去十几年时间里,海洋宽频地震采集和配套处理技术取得了长足进展,在我国南海深水区已采集地震资料的频带宽度已达5个倍频程,低频信息可拓展至3 Hz,高频信息可达120 Hz.与常规地震数据相比,宽频地震数据中子波的波形特征有了明显变化,除了可以大幅提升地震资料的信噪比和改善中深层地震成像精度外,在地震属性计算过程中还有很多明显的优势.本文从瞬时振幅属性计算原理出发,通过模型对比分析了常规子波与宽频子波在瞬时振幅属性计算方面的差异及产生原因.分析表明,宽频地震数据可以有效降低瞬时振幅属性计算结果的误差,有效提高基于振幅属性进行储层刻画和储层物性参数预测的精度.最后,将该方法应用于南海深水区实际数据的对比中,进一步阐明了宽频地震数据在瞬时振幅属性计算方面的优势,有效支持了深水区勘探进程,取得了良好的应用效果.     

在煤矿区用三分量地震和地电勘探进行参数估计和断层探测

为测定本地岩石物性参数的分布并探测煤层中的不均一性,在匈牙利米什科尔茨附近的Lyukobanya煤矿采用了三分量地震和地电勘探方法。地震测量包括地下体波垂直地震剖面法,以及用槽波技术探测煤层中的地震波振幅—深度分布和传输特性。地电探测采用地电漂测和煤层测深法。     

HTI煤层方位AVO响应与裂隙识别

煤层在顶板压实作用下水平裂隙近乎闭合,多垂向裂隙发育,因此将该类煤层等效为HTI介质,研究裂隙密度和填充物类型对方位AVO的影响,可以为预测裂隙提供理论依据,对煤田勘探有重要意义.本文基于Thomsen各向异性理论和模型等效理论建立上层为各向同性介质而下层为垂向裂隙发育的HTI煤层的正演模型,推导出适用于所建模型的更高精度反射系数近似公式对不同裂隙密度、不同填充物类型的模型进行方位AVO数值模拟,并利用反射系数进行地震记录合成;从反射系数空间曲面和地震记录两方面分析不同模型随着入射角、方位角、裂隙密度、裂隙填充物的改变而产生的不同地震响应.结果表明:裂隙密度的增大导致反射系数空间曲面波幅增大,地震记录波振幅增大;裂隙密度相同时,饱和水裂隙模型和干裂隙模型的反射系数空间曲面和合成地震记录存在显著差异;方位角为0°时,饱和水裂隙模型和干裂隙模型的反射系数差值达到0.2,分辨性较强;在方位角为0.时,入射角大于45.时地震记录差异最显著.测试数据中,含饱和水裂隙煤层的反射系数绝对值低于干裂隙煤层,地震记录的振幅也低于干裂隙煤层.     

地震信号的复地震道分析及应用

复地震道分析又称三瞬分析,该分析方法可将反映地震信号局部变化情况的地震波的瞬时振幅、瞬时相位和瞬时频率等信息分离开.本文应用Hilbert变换求解虚地震记录,用复地震道分析方法求取"三瞬"信息,并用该方法计算了理论合成地震记录的瞬时振幅、瞬时相位和瞬时频率,获得了较好的效果.同时,本文也利用该方法对某区块实际地震资料进行了处理,结果表明,复地震道分析方法获得的"三瞬"信息可反映地震信号的局部变化,有助于进行地震薄互层分析,并能提高数据的解释精度.     

地震波形反演技术在砂泥岩薄互层结构表征中的应用

基于传播矩阵理论开发砂泥岩薄互层地震合成记录算法,与褶积算法、基于界面模型的Zoeppritz方法以及波动方程等方法相比,该方法更适用于具有复杂结构的薄互层模型,能够在充分考虑地震反射波动力学因素的同时不受网格间距的限制.基于正演算法开发了基于波形对比的砂泥岩薄互层地震反演技术,由地震反射波形特征的变化反演薄地层单元中砂体含量与空间位置等参数,进而确定薄互层段砂泥岩组合结构以及砂体的空间展布.理论模型验证了反演方法的有效性.通过测井分析建立薄互层地震地质模型,并将该技术应用于研究区实际地震数据,反演的砂体空间分布与测井资料进行对比分析,验证了反演方法的实用性.     

Windowless Q-factor tomography by the instantaneous frequency

The estimation of the Q factor of rocks by seismic surveys is a powerful tool for reservoir characterization, as it helps detecting possible fractures and saturating fluids. Seismic tomography allows building 3D macro-models for the Q factor, using methods as the spectral ratio and the frequency shift. Both these algorithms require windowing the seismic signal accurately in the time domain; however, this process can hardly follow the continuous variations of the wavelet length as a function of offset and propagation effects, and it is biased by the interpreter choice. In this paper, we highlight some drawback of signal windowing in the frequency-shift method, and introduce a tomographic approach to estimate the Q factor using the complex attributes of the seismic trace. We show that such approach is particularly needed when the dispersion is broadening the waveforms of signals with a long wave-path. Our method still requires an interpretative event picking, but no other parameters as the time window length and its possible smoothing options. We validate the new method with synthetic and real data examples, involving the joint tomographic inversion of direct and reflected signals. We show that a calibration of the frequency-shift method is needed to improve the estimation of the absolute Q factor, otherwise only relative contrasts are obtained.     

Asymptotic Rayleigh instantaneous unit hydrograph

The instantaneous unit hydrograph for a channel network under general linear routing and conditioned on the network magnitude,N, tends asymptotically, asN grows large, to a Rayleigh probability density function. This behavior is identical to that of the width function of the network, and is proven under the assumption that the network link configuration is topologically random and the link hydraulic and geometric properties are independent and identically distributed random variables. The asymptotic distribution depends only on a scale factor, , where is a mean link wave travel time.     

Asymptotic Rayleigh instantaneous unit hydrograph

The instantaneous unit hydrograph for a channel network under general linear routing and conditioned on the network magnitude,N, tends asymptotically, asN grows large, to a Rayleigh probability density function. This behavior is identical to that of the width function of the network, and is proven under the assumption that the network link configuration is topologically random and the link hydraulic and geometric properties are independent and identically distributed random variables. The asymptotic distribution depends only on a scale factor, , where is a mean link wave travel time.     

Development of the instantaneous unit hydrograph using stochastic differential equations

Recognizing that simple watershed conceptual models such as the Nash cascade ofn equal linear reservoirs continue to be reasonable means to approximate the Instantaneous Unit Hydrograph (IUH), it is natural to accept that random errors generated by climatological variability of data used in fitting an imprecise conceptual model will produce an IUH which is random itself. It is desirable to define the random properties of the IUH in a watershed in order to have a more realistic hydrologic application of this important function. Since in this case the IUH results from a series of differential equations where one or more of the uncertain parameters is treated in stochastic terms, then the statistical properties of the IUH are best described by the solution of the corresponding Stochastic Differential Equations (SDE's). This article attempts to present a methodology to derive the IUH in a small watershed by combining a classical conceptual model with the theory of SDE's. The procedure is illustrated with the application to the Middle Thames River, Ontario, Canada, and the model is verified by the comparison of the simulated statistical measures of the IUH with the corresponding observed ones with good agreement.     

Development of the instantaneous unit hydrograph using stochastic differential equations

Recognizing that simple watershed conceptual models such as the Nash cascade ofn equal linear reservoirs continue to be reasonable means to approximate the Instantaneous Unit Hydrograph (IUH), it is natural to accept that random errors generated by climatological variability of data used in fitting an imprecise conceptual model will produce an IUH which is random itself. It is desirable to define the random properties of the IUH in a watershed in order to have a more realistic hydrologic application of this important function. Since in this case the IUH results from a series of differential equations where one or more of the uncertain parameters is treated in stochastic terms, then the statistical properties of the IUH are best described by the solution of the corresponding Stochastic Differential Equations (SDE's). This article attempts to present a methodology to derive the IUH in a small watershed by combining a classical conceptual model with the theory of SDE's. The procedure is illustrated with the application to the Middle Thames River, Ontario, Canada, and the model is verified by the comparison of the simulated statistical measures of the IUH with the corresponding observed ones with good agreement.     

地震信号瞬时频率的估算

本文比较了四类计算瞬时频率的方法.基于相位差分的方法对噪声敏感;基于零交叉点的方法是针对周期信号提出的,对非周期信号效果不理想,通过插值改善估算结果;基于FIR微分器的方法有三种,基于两点的FIR方法与标准公式较为接近,但会引入半个采样间隔的时移;基于三点的FIR方法可以消除时移,但计算结果会出现负频尖峰;Claerbout方法不仅会引入半个采样间隔的时移,而且估算的频率值可能超过Nyqusit频率.本文在Claerbout公式的基础上导出了一种估算瞬时频率的公式,该公式消除了时移,且负频尖峰也得到抑制;基于时频表示一阶矩的方法的计算结果较为平滑,同时具有一定的抗噪能力.最后用本文导出的公式和时频表示一阶矩两种方法计算了南海东北部一条地震剖面的瞬时频率,并将其结果与Seismic Unix中相关函数的计算结果做了比较,表明本文导出公式的计算结果较为理想.     

The use of instantaneous velocity in uplift investigations

Uplift and the accompanying reduction in overburden result in anomalously high velocity in the uplifted rock unit relative to its current depth. The present work utilizes the non‐uniqueness of the parameters of instantaneous velocity versus depth functions as an effective tool for uplift studies. The linear function with its two parameters, V₀ and k, is a very simple function and is used as the illustrative vehicle. In the parameter space, i.e. in a plot where one axis represents V₀ and the other axis represents k, non‐uniqueness can be represented by contours of equal goodness‐of‐fit values between the observed data and the fitted function. The contour delimiting a region of equivalent solutions in the parameter space is called a ‘solution trough’. Uplift corresponds to a rotation of the solution trough in the parameter space. It is shown that, in terms of relative depth changes, there are five possible configurations (five cases) of uplift in a given area (the mobile location) relative to another area (the reference location). The cases depend on whether the uplifted location had attained a (pre‐uplift) maximum depth of burial that was greater than, similar to, or smaller than the maximum depth of burial at the reference location. Interpretation of the relationships between the solution troughs corresponding to the different locations makes it possible to establish which of the five cases applies to the uplifted location and to estimate the amount of uplift that the unit had undergone at that location. The difficulty in determining the reduction in velocity due to decompaction resulting from uplift is a main source of uncertainty in the estimate of the amount of uplift. This is a common problem with all velocity‐based methods of uplift estimation. To help around this difficulty, the present work proposes a first‐order approximation method for estimating the effect of decompaction on velocity in an uplifted area.     

结构瞬时最优控制参数影响的数值分析

在瞬时最优控制算法理论分析的基础上，分别以单自由度和三自由度结构模型为例，研究了时间间隔和权矩阵对结构控制反应的影响。首先，进行了瞬时最优控制算法的理论分析，提出了控制算法的影响参数；其次，分别对单自由度和三自由度结构在无控、LQR和瞬时最优三种方法控制下，分析了时间间隔和权矩阵对结构反应的影响。结果表明：时间间隔和权矩阵对结构瞬时最优控制效果影响很大。     

Correlation of the velocity parameter of three geomorphological instantaneous unit hydrograph models

Three geomorphological instantaneous unit hydrograph (GIUH) models are investigated. These GIUHs were derived as a function of watershed geomorphological characteristics. The geomorphological input parameters of the models were determined for 10 basins in Indiana, USA. The three GIUH models were used to simulate 187 observed runoff hydrographs of these basins. The non-measurable velocity parameters of the GIUH models were optimized and the relationships between them were investigated. The results of the investigation show that the velocity parameters of the three models are correlated. © 1998 John Wiley & Sons, Ltd.