共查询到20条相似文献，搜索用时 171 毫秒
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多种岩石的Qp,Qs,Qc 总被引：2，自引：0，他引：2
本采用脉冲传播谱振幅比法、能量法、尾波法分别测多种岩样的Ｐ波Ｑ值、Ｓ波Ｑ值及尾波Ｑ值。结果表明，能量法所得Ｑｐ、Ｑｓ较小。谱振幅比法所得Ｑｐ一般居中，Ｑｓ较大。尾波Ｑｃ有的偏大，有的偏小。 相似文献
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用能量法测定柱状样品的衰减Q值 总被引：1，自引：0，他引：1
对常用的测试衰减Ｑ值的频谱振幅比法和波形反常进行了分析,认为它们对样品几何开头和大小的严格要求是大多数实验室待测样品所不能满足的。因而,提出用波形的能量来计算衰减Ｑ值的方法,阐述了其原理、计算公式和注意事项,讨论了ＱＰ和ＱＥ之间的关系,并对多种样品进行了实验室测量,将本文方法测得的Ｑ值与其它方法测试值进行了比较。认为本方法的Ｑ值介于ＱＰ和ＱＥ之间。 相似文献
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采用脉冲传播谱振幅比法、能量法和尾波法分别测定片麻岩破裂孕育过程中的Ｑ值变化．结果表明:谱振幅比法所得Ｑ值呈现相对平稳值——升高至甚高值(极大值)——回降——破裂的变化形式；能量法所得Ｑ值变化形态与上述相反，即平稳值——低值——回升——破裂；而尾波法所得Ｑ值，主频Ｑ值呈现相对高值——下降至低值(极小)——回升——破裂，与能量法Ｑ值变化大体一致．而对于高频(大于主频)Ｑ值则呈现平稳值——升高至极大值——回降——破裂．同时尾波振幅谱还表明:应力达70％破裂应力后，首先是高频Ｓ波迅速减少(QC)变大)，临近主破裂时主频Ｓ波则大幅度减少(QC回升)，这可能是两种尾波QC变化形态不同的原因所致．而P，S波(初至波)振幅谱也表明，随着裂隙出现，Ｓ波频带变窄，高频成分迅速减少．即S波谱变化不同．这使采用不同方法所得的QS的变化特征不同． 相似文献
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京西北延庆—怀来盆地的QSH值和小震震源参数的测定 总被引：4，自引：1，他引：4
用在一个地震台接上到的同一震源区内的较小地震的振幅谱去除大地震的振幅谱，求得较大地震震源同频趋势的斜率。利用Ｑ值在０．０００１－１００Ｈｚ之间几乎是常数是特性，用网格搜寻法对较大地震的振幅谱因衰减造成的损耗进行补偿，同时确定自震源对地震吧途径上的介持的品质因数、拐角频率和补偿后的频谱的零频极限。用这种方法，利用中－欧合作北京西北怀来数字地震台网的记录，确定了延庆－怀来盆地的品质因数ＱＳＨ值并测定了 相似文献
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利用数字化地震记录进行震源参数和介质衰减特性的联合反演 总被引：1，自引：0，他引：1
利用区域台网的数字化地震记录资料，发展了一种体波谱的反演方法，以消除用波谱分析求解震源参数和介质衰减特性过程中的不确定因素的影响．经过数值实验和对实际资料的应用，初步证明了该方法的实用性。利用滦县地区流动台网中的五个台站接收的３５次地震记录的Ｐ波频谱资料，反演了滦县地区的震源动力学参数，得到了５个台站的Ｐ波表现Ｑ值和震源频谱的高频衰减率γ。Ｑ值分布在４０８－８４７之间，均值为５２０。γ值分布在１．５４－３．２２之间，均值为２．４１。利用唐山仪器台阵中的７个台站接收的９次地震记录的Ｓ波频谱资料，反演了唐山滦县地区的震源动力学参数，并得到了７个台站所在的小区域内平均的Ｓ波表观Ｑ值和震源频谱的高频衰减率γ。Ｑ值的均值为５８３。γ值均值为２．５８。 相似文献
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地层品质因子Q的可用于地震资料高分辨率处理,而从VSP资料下行直达波更容易获取准确的地层品质因子。通过对零偏移距VSP资料的监控子波和下行初至波的频谱进行综合分析,仿照Ricker子波频谱的表达式,本文提出了震源子波频谱新的表达式。在震源子波频谱新的表达式基础上,我们介绍了改进的频谱拟合法和改进的谱比法的层Q值反演方法及相应的处理流程。基于本文提出的层Q值反演方法,利用实际的零偏移距VSP资料的下行直达波,反演稳定的层Q值,并用于零偏移距VSP资料及井旁地面地震资料的反Q滤波振幅补偿处理,提高了地震资料的分辨率。 相似文献
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《应用地球物理》2019,(4)
品质因子Q是表征岩石非弹性性质的重要参数,准确的Q值是深入研究岩石动力学特征的关键。准确、稳定地获得岩石Q值参数一直是一个难点。本文利用时频谱信息进行Q值提取,提出了基于S变换的频谱比法(SR-ST)。该方法利用了S变换的变时窗特性解决常规方法中的时窗问题,并对S变换中高斯窗添加时窗因子,使得高斯窗更适合超声衰减计算。同时,通过给出频带线性回归规则,提高计算的稳定性和准确性。文中首先通过数值模拟和标准样品测量实验,研究分析了SR-ST方法的可行性行以及影响因素;其次利用不同Q值人工样品,研究该方法对不同Q值样品计算的适应性和稳定性;最后通过岩石超声衰减测量实验,将该方法与常规频谱比法进行对比分析,分析SR-ST方法的稳定性和准确性。实验结果表明:利用无时窗因子的S变换时频谱计算,会引起36%的误差,需要对S变换添加时窗因子,适当调整时窗大小随频率变化的程度;SR-ST方法能够适应不同衰减特征岩石样品Q值计算,利用给出的频带线性回归规则以及平均斜率值进行Q值计算,能够保证不同Q值(Q15)的最大误差在10%以内。 相似文献
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地形条件对局部震害分布有重要影响。本文选择地形起伏剧烈的芦山地区,采用三维谱元法模拟地震波传播。研究了该地区地震动的频谱特征。计算了测线上位于山顶和山谷的台站傅里叶频谱,并研究了各自的谱值和谱值比特征。分析结果表明:山顶包含了较高的频谱;山谷包含了较低的频谱;山顶上的频谱值高于山谷的频谱值;并且地形对水平分量的影响更大。同时,进一步从频谱中提取了峰值放大比和峰值频率2个参数,分析了其在芦山地形中的分布特征。结果显示,山顶对应了较大的峰值放大比和峰值频率,而山谷则对应了较低的峰值放大比和峰值频率。 相似文献
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We describe a new laboratory technique for measuring the compressional wave velocity and attenuation of jacketed samples of unconsolidated marine sediments within the acoustic (sonic) frequency range 1–10 kHz and at elevated differential (confining – pore) pressures up to 2.413 MPa (350 psi). The method is particularly well suited to attenuation studies because the large sample length (up to 0.6 m long, diameter 0.069 m) is equivalent to about one wavelength, thus giving representative bulk values for heterogeneous samples. Placing a sediment sample in a water‐filled, thick‐walled, stainless steel Pulse Tube causes the spectrum of a broadband acoustic pulse to be modified into a decaying series of maxima and minima, from which the Stoneley and compressional wave, velocity and attenuation of the sample can be determined. Experiments show that PVC and copper jackets have a negligible effect on the measured values of sediment velocity and attenuation, which are accurate to better than ± 1.5% for velocity and up to ± 5% for attenuation. Pulse Tube velocity and attenuation values for sand and silty‐clay samples agree well with published data for similar sediments, adjusted for pressure, temperature, salinity and frequency using standard equations. Attenuation in sand decreases with pressure to small values below Q?1 = 0.01 (Q greater than 100) for differential pressures over 1.5 MPa, equivalent to sub‐seafloor depths of about 150 m. By contrast, attenuation in silty clay shows little pressure dependence and intermediate Q?1 values between 0.0206–0.0235 (Q = 49–43). The attenuation results fill a notable gap in the grain size range of published data sets. Overall, we show that the Pulse Tube method gives reliable acoustic velocity and attenuation results for typical marine sediments. 相似文献
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目前固井质量评价主要是利用套管中模式波的幅度或衰减变化判断套管与水泥间的胶结状况.在超声测量频段（70~500 kHz）,现有声波测井仪器工作时在套管中激发的模式波类似薄板中的对称兰姆波（拉伸波）或反对称兰姆波（弯曲型兰姆波）.本文将黏弹滑移界面理论应用到套管和水泥的耦合界面,探讨了套管中的准兰姆波（包括拉伸波和弯曲型兰姆波）与套管后物质的耦合方式,拉伸波与套后物质主要以剪切刚度耦合,即便是0.01 mm的微环也会使得拉伸波的衰减明显降低,接近套后是流体时的响应特征;而弯曲型兰姆波与套管后物质主要以法向刚度耦合,这使得在套后胶结轻质水泥时弯曲型兰姆波对微环不敏感,在套后耦合常规水泥时微环的存在又会使得弯曲型兰姆波的衰减明显增强,衰减的增加说明其与套后物质的声耦合更紧密,也表明微环与常规水泥的等效声阻抗适当降低,更有利于弯曲型兰姆波传播时与套后介质实现法向刚度的匹配.拉伸波和弯曲型兰姆波对同一胶结状况的不同响应特征也为固井质量综合评价时区分不同的水泥胶结状况提供了可能. 相似文献
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This paper presents a methodology for constructing seismic design spectra in near-fault regions.By analyzing the characteristics of near-fault pulse-type ground motions,an equivalent pulse model is proposed,which can well represent the characteristics of the near-fault forward-directivity and fling-step pulse-type ground motions.The normalized horizontal seismic design spectra for near-fault regions are presented using recorded near-fault pulse-type ground motions and equivalent pulse-type ground motions,which are derived based on the equivalent pulse model coupled with ground motion parameter attenuation relations.The normalized vertical seismic design spectra for near-fault regions are obtained by scaling the corresponding horizontal spectra with the vertical-to-horizontal acceleration spectral ratios of near-fault pulse-type ground motions.The proposed seismic design spectra appear to have relatively small dispersion in a statistical sense.The seismic design spectra for both horizontal and vertical directions can provide alternative spectral shapes for seismic design codes. 相似文献
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Acoustic impedance is one of the best attributes for seismic interpretation and reservoir characterisation. We present an approach for estimating acoustic impedance accurately from a band‐limited and noisy seismic data. The approach is composed of two stages: inverting for reflectivity from seismic data and then estimating impedance from the reflectivity inverted in the first stage. For the first stage, we achieve a two‐step spectral inversion that locates the positions of reflection coefficients in the first step and determines the amplitudes of the reflection coefficients in the second step under the constraints of the positions located in the first step. For the second stage, we construct an iterative impedance estimation algorithm based on reflectivity. In each iteration, the iterative impedance estimation algorithm estimates the absolute acoustic impedance based on an initial acoustic impedance model that is given by summing the high‐frequency component of acoustic impedance estimated at the last iteration and a low‐frequency component determined in advance using other data. The known low‐frequency component is used to restrict the acoustic impedance variation tendency in each iteration. Examples using one‐ and two‐dimensional synthetic and field seismic data show that the approach is flexible and superior to the conventional spectral inversion and recursive inversion methods for generating more accurate acoustic impedance models. 相似文献
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套管井声全渡中的地层波可以检测固井第二界面的水泥胶结质量状况.地层波不仅受地层衰减、套管波干扰等因素影响,更主要受第二界面两侧的声阻抗差值的影响.为此,基于固体介质的声势函数和界面的边界条件,推导了固-固界面纵横波的反射系数和透射系数,以及第一临界角入射情况下反射系数和透射系数的近似公式,并且分析了透射系数与声阻抗之间的关系.数值计算结果发现,地层波幅度随第二界面两侧声阻抗差增大而减小,且这种关系是非线性的.基于临界入射的透射系数,对经过衰减校正和干扰校正的地层波进行声阻抗校正,消除地层声阻抗对地层波幅度影响.使用地层波幅度评价第二界面的水泥胶结状况,并在实际资料处理中见到了好的效果. 相似文献
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黏弹性衰减因子Q的可靠估计可通过Q反褶积来提高地震资料的分辨率并有助于振幅分析. 本文从小波理论出发,结合地震波在黏弹性介质中的传播方程,推导出小波尺度域地震波能量衰减公式. 能量衰减公式具有下列性质：（1）Q值越大,能量衰减得越慢;Q值越小,能量衰减越严重;（2）尺度越小,信号中保留的能量越少;（3）对于脉冲源来说在理想的无衰减介质(即Q趋近于∞)中传播时,信号在不同尺度内的能量相同. 利用尺度能量公式,可从反射地震资料中直接估计品质因子Q（即衰减因子）,也可以提取不同尺度的能量衰减剖面作为储层描述的属性参数,用来进行岩性识别和指示气藏,与经典的谱比法相比,避免了谱比法所面临的双时窗问题以及进行谱估计的窗选择问题. 理论模型试验表明了本文方法的正确性和有效性. 相似文献
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Ultrasonic cement bond logging is a widely used method for evaluating cementing quality. Conventional ultrasonic cement bond logging uses vertical incidence and cannot accurately evaluate lightweight cement bonding. Oblique incidence is a new technology for evaluating cement quality with improved accuracy for lightweight cements. In this study, we simulated models of acoustic impedance of cement and cementing quality using ultrasonic oblique incidence, and we obtained the relation between cementing quality, acoustic impedance of cement, and the acoustic attenuation coefficient of the A0-mode and S0-mode Lamb waves. Then, we simulated models of different cement thickness and we obtained the relation between cement thickness and the time difference of the arrival between the A0 and A0′ modes. 相似文献
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The significant development in acoustic full waveform logging during the last ten years has made it increasingly possible for log analysts to determine the physical properties of a rock formation in situ. Parallel to the methods applied to a single wavetrain during seismic processing, the new techniques, used for sets of wavetrains, have been successfully tested with acoustic full waveforms. Instantaneous characteristics analysis is included in this group of methods. This approach, leading to qualitative and quantitative interpretation, reveals the influence of small changes in physical properties on acoustic full wavetrains. Applications of complex acoustic waveform analysis for the determination of inhomogeneous zones are presented. Colour diagrams of instantaneous characteristics are used for the detection of fractured regions and slow formations with increased attenuation of acoustic waves. Results of the interpretation of individual acoustic full waveforms, based on cross-correlation and spectral analysis, using the IDNP and IDNS computer programs, e.g. velocities of compressional waves, shear and Stoneley waves, are presented. Since the bulk density of the rocks was known, it was possible, using the velocities of P- and S-waves obtained, to calculate the dynamic elastic moduli. We used the interpretation of acoustic full wavetrains to calculate porosity. The sonic porosity is compared to the porosity obtained from other logs and to that obtained from core sample analysis. The examples of acoustic full wavetrains were recorded in the Miocene sulphur-bearing limestones in central Poland. Field measurements were made using the domestic prototype equipment for well log recordings in shallow boreholes. 相似文献