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1.
基于精细积分法的三维弹性波数值模拟(英文) 总被引：1，自引：0，他引：1
波动方程有限差分法是地震数值模拟中的一种重要的方法,对理解和分析地震传播规律、分析地震属性和解释地震资料有着非常重要的意义。但是有限差分法由于其离散化的思想,产生了不稳定性。精细积分法在有限差分法的基础上,在时间域采用解析解的表达形式,在空间域保留任意差分格式,发展成为半解析的数值方法。本文结合并发展了以往学者的成果,推导了任意精细积分法的三维弹性波正演模拟计算公式,并对其稳定性进行了数值分析。在计算实例中,实现了精细积分法二维和三维弹性波模型的地震正演模拟,对计算结果的分析表明,精细积分法反射信号走时准确,稳定性好,弹性波场相较于声波波场,弹性波波场成分更为丰富,包含了更多波型成分(PP-和PS-反射波、透射波和绕射波),这对实际地震资料的解释和储层分析有重要的意义。实践证明,该方法可直接应用到弹性波的地质模型的数值模拟中。 相似文献
2.
ABSTRACTTurbulence is considered to generate and drive most geophysical processes. The simplest case is isotropic turbulence. In this paper, the most common three-dimensional power-spectrum-based models of isotropic turbulence are studied in terms of their stochastic properties. Such models often have a high order of complexity, lack stochastic interpretation and violate basic stochastic asymptotic properties, such as the theoretical limits of the Hurst coefficient, when Hurst-Kolmogorov behaviour is observed. A simpler and robust model (which incorporates self-similarity structures, e.g. fractal dimension and Hurst coefficient) is proposed using a climacogram-based stochastic framework and tested over high-resolution observational data of laboratory scale as well as hydro-meteorological observations of wind speed and precipitation intensities. Expressions of other stochastic tools such as the autocovariance and power spectrum are also produced from the model and show agreement with data. Finally, uncertainty, discretization and bias related errors are estimated for each stochastic tool, showing lower errors for the climacogram-based ones and larger for power spectrum ones. 相似文献
3.
交叉梯度联合反演方法通过对多种地球物理模型实现结构耦合,在岩石物性关系不确定的情况下,既能提高反演结果的可靠性,又能减少反演的多解性,还能减少不同方法解释结果之间的矛盾.当不同的模型观测数据覆盖范围不一致时,交叉梯度联合反演通常需要取出重叠区域数据进行联合反演,并且建模时还要扩展一些模型范围.本文首先提出并实现了部分区域约束下的交叉梯度多重地球物理数据联合反演算法;接着进行了算法的模型试算;最后,我们将该反演算法用于本溪—集安深部地质调查重磁电综合地质地球物理解释中.结果表明:该算法不但能在重叠区域内很好地恢复结构相似的模型,而且在非重叠区域与重叠区域的边界处仍然可以得到平滑变化的模型;在本溪—集安10号剖面所获得的结构上相似的电阻率、密度及磁化率模型较好地反映了该区的深部地质结构,对于确定深部地质体的性质提供了有力的证据. 相似文献
4.
对常用的Waples、Middleton及Easy%Ro模型,通过蒙特卡罗方法,得到了相应的简化模型.所有简化模型均表明镜质体反射率(Ro)主要受控于最高温度(Tmax),并且与最高温度附近的温度变化率(Hr)有关.通过对简化模型的比较发现：(1)相对于Easy%Ro模型而言,Waples、Middleton模型对Hr的变化更为敏感;(2)总的来讲,达到相同的Ro值Middleton模型需要的温度最高,Easy%Ro模型其次,Waples模型需要的温度最低.在一定条件下,根据简化模型,利用实测的lnRo-H数据可以求取地层经历的最高温度及相应的地温梯度、热流和时间.实例分析表明岩石热导率等数据的准确性直接影响Ro解释的结果,但这种影响容易分析,而Hr的不确定性则导致多解性. 相似文献
5.
Mrta Kis 《Journal of Applied Geophysics》2002,50(4)
Horizontally layered (1D) earth models are often assumed as a model estimate for the interpretation of geophysical data measured along 2D geological structures. In this process, the individual data sets are usually inverted independently, and it is considered only in a later phase of interpretation that these local (1D) models have common characteristic features. Taking account of these common attributes, instead of the successive independent interpretations, the lateral variations of geometrical and petrophysical parameters can be efficiently determined for the whole 2D structure by applying a series expansion. Using global basis functions, two advantages can be achieved: (i) choosing an appropriate number of basis functions helps us to restrict the complexity of the model; (ii) the integration of all the data sets measured along the profile gives rise to the application of simultaneous or joint inversion methods. This results in a decrease of the number of independent unknowns, a higher stability during the inversion and a more accurate and reliable parameter estimation.In this paper, a joint inversion algorithm is presented using DC geoelectric apparent resistivities and refraction seismic travel times measured along various layouts above a 2D geological model. To describe lateral variations series, expansions are used, and furthermore, to improve the often used approximation of a (locally) 1D forward modelling, the integral mean value of the horizontally changing model parameters (calculated along an appropriately defined interval) is introduced. We call the inversion procedure that combines series expansions and the concept of integral mean Generalised Series Expansion (GSE) inversion. The method was developed and tested for both the simultaneous (integrating data sets of one method or methods on the same physical basis) and the joint inversion (where data sets of methods on different physical bases are joined together), using synthetic and field data sets. It is also demonstrated that the equivalence problem inherent in the independent inversion of DC geoelectric data can efficiently be resolved by the use of the joint GSE inversion method in the cases of conductive and resistive equivalent geological models. 相似文献
6.
L. E. Sobisevich E. A. Rogozhin A. L. Sobisevich To Shen Ziao Liu 《Seismic Instruments》2017,53(1):28-45
The paper presents results of instrumental observations of seismic processes and variations in the Earth’s magnetic field at the stages of nucleation and development of earthquakes in the Chinese provinces of Qinghai, Sichuan and Yunnan. Data on manifestations of all these strong seismic events are indicated. Monitoring of the changes in the magnetic field is based on data obtained at the Northern Caucasus Geophysical Observatory, IPE RAS and integrated observation points of the Institute of Terrestrial Magnetism, the Ionosphere and Radio Wave Propagation, RAS (IZMIRAN). The experimental results have allowed us to represent the structure of induced anomalous geomagnetic disturbances, which can be associated with the development of related geodynamic processes in the geological medium of the seismic source zone. 相似文献
7.
AJIT K. SINHA 《Geophysical Prospecting》1983,31(4):627-648
Airborne electromagnetic methods are most commonly used in mineral exploration. However, new developments, such as multifrequency capability and digital on-board field recording, as well as improvements in instrumentation resulting in high signal-to-noise ratios in recorded data, have made their application in geological mapping possible. A three-frequency airborne EM survey carried out over an area northwest of Timmins, Ontario, was interpreted in terms of thickness and resistivity of the layers of a two-layer earth section. Since both in-phase and quadrature components are measured, this provides six independent parameters at each point in space. Based on prior geological information and a preliminary interpretation of the field records, two two-layer models of the subsurface seemed to be appropriate for most of the survey area. An automatic computerized interpretation procedure was devised to interpret the field data at each point in terms of thickness and resistivity parameters of those two models. When the geology is more complex, the data do not fit the models and no interpretations are made. Two maps illustrating the variation of the resistivity and the thicknesses of the layers were constructed from the interpreted data. These maps agree with the known geological information about the distribution of glacial clay in the area. Areas where the layered models do not fit are known to be areas where the geology is complex with a large number of dykes and other lateral inhomogeneities. The study shows that multifrequency airborne EM surveys can be very useful in geological mapping over inaccessible terrain and can significantly help the mapping geologist where outcrops are scarce. 相似文献
8.
A pseudo-seismic interpretation method is an alternative way to process and explain transient electromagnetic (TEM) data, and has become a popular research field in recent years. TEM signals which satisfy the diffusion equation can be converted by means of a mathematical transformation into ones which obey the wave equation. For an ill-posed problem of this kind of transformation, a sub-regularization algorithm is developed in this paper to extract a virtual wavelet of the TEM field. According to the conventional designation of TEM recordings, the entire integration period is divided into seven time intervals. In order to avoid low accuracy in the calculations, high-density wavefield data has been calculated based on the former sub-division. Therefore, the virtual wavelet can be extracted successfully by using an optimized algorithm to obtain high-density integral coefficients for all time windows, and a satisfactory condition number of the coefficient matrix while taking a different channel number in each time period. The Tikhonov regularization inversion scheme is used to determine the optimal parameters based on minimizing a least squares misfit, and the Newton iterative formula is used to obtain optimal regularization parameters. Both synthetic model simulations and a real data interpretation example indicate that the proposed pseudo-seismic wavefield method is a suitable alternative way to interpret TEM data. 相似文献
9.
Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions 总被引：5，自引：1，他引：4
Measurements of the splitting or birefringence of seismic shear waves that have passed through the Earth’s mantle yield constraints on the strength and geometry of elastic anisotropy in various regions, including the upper mantle, the transition zone, and the D″ layer. In turn, information about the occurrence and character of seismic anisotropy allows us to make inferences about the style and geometry of mantle flow because anisotropy is a direct consequence of deformational processes. While shear wave splitting is an unambiguous indicator of anisotropy, the fact that it is typically a near-vertical path-integrated measurement means that splitting measurements generally lack depth resolution. Because shear wave splitting yields some of the most direct constraints we have on mantle flow, however, understanding how to make and interpret splitting measurements correctly and how to relate them properly to mantle flow is of paramount importance to the study of mantle dynamics. In this paper, we review the state of the art and recent developments in the measurement and interpretation of shear wave splitting—including new measurement methodologies and forward and inverse modeling techniques,—provide an overview of data sets from different tectonic settings, show how they help us relate mantle flow to surface tectonics, and discuss new directions that should help to advance the shear wave splitting field. 相似文献
10.
11.
《Marine pollution bulletin》2008,56(10-12):407-414
The EU Water Framework Directive demands the protection of the functioning and the structure of our aquatic ecosystems. The defined means to realize this goal are: (1) optimization of the habitat providing conditions and (2) optimizing the water quality. The effects of the measures on the structure and functioning of the aquatic ecosystems then has to be assessed and judged. The available tool to do this is ‘monitoring’. The present monitoring activities in The Netherlands cover target monitoring and trend monitoring. This is insufficient to meet the requirements of the EU. It is, given the EU demands, the ongoing budget reductions in The Netherlands and an increasing flow of unused new ecological concepts and theories (e.g. new theoretical insights related to resource competition theory, intermediate disturbance hypothesis and tools to judge the system quality like ecological network analysis) suggested to reconsider the present monitoring tasks among governmental services (final responsibility for the program and logistic support) and the academia (data analyses, data interpretation and development of concepts suitable for ecosystem modelling and tools to judge the quality of our ecosystems). This will lead to intensified co-operation between both arena’s and consequently increased exchange of knowledge and ideas. Suggestions are done to extend the Dutch monitoring by surveillance monitoring and to change the focus from ‘station oriented’ to ‘area oriented’ without changing the operational aspects and its costs. The extended data sets will allow proper calibration and validation of developed dynamic ecosystem models which is not possible now. The described ‘cost-effective’ change in the environmental monitoring will also let biological and ecological theories play the pivotal role they should play in future integrated environmental management. 相似文献
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13.
Zhang Yanling Yang Changchun Jia Shuguang Gao Xiaohui 《应用地球物理》2006,3(1):55-61
It is very important to comprehensively interpret areal seismic data with geological data in a research area. For the structural interpretations in the middle depression of the eastern basin of Liaohe oilfield, we first analyze and study geological phenomena on outcrop pictures collected in the field and establish geological outcrop models. Second, we make fault and structural interpretations based on the structural characteristics of the outcrop pictures. Third, we analyze the migration, accumulation, and formation of oil and gas using characteristics of seismic profiles. By geologic and geophysical comprehensive interpretation, it is inferred that, in the research area, the dominant factor controlling oil and gas accumulation is strike-slip faults. Structural modes and the relationship of the oil and gas in the Huangshatuo and Oulituozi oil fields are also analyzed and investigated. 相似文献
14.
—Different techniques in Geophysics and Geology are used to derive the structure of the subsurface. They are based on different data sets, i.e., seismic and geological data, and a combination of these techniques should produce better earth models. The case study presented in this paper is based on data of the German Continental Reflection program (DEKORP) collected in the Münsterland basin and the Rhenish Massif located at the northern border of the Rhenohercynian fold and thrust belt of the Mid-European Variscides. In this study we present an attempt to integrate balanced profiles, i.e., structural geology, and reflection seismics. The integration is performed by synthetically modelling seismic waves according to the acquisition of the field data, where the velocity model is based on the balanced profile. The synthetic data are compared with the field observations. Differences between observed data and field data are either caused by velocity errors in the model or by errors in the balanced profile. Criteria are developed to interpret these differences in order to improve the joint model of geologists and geophysicists. The case study presented in this paper shows that the combination of balanced profiles and reflection seismics may lead to shortcuts in the determination of seismic velocities of the subsurface. These shortcuts can reduce processing times and processing costs of reflection seismic data. 相似文献
15.
Temperature profiles in the earth of importance to deep electrical conductivity models 总被引：3，自引：0，他引：3
Deep in the Earth, the electrical conductivity of geological material is extremely dependent on temperature. The knowledge of temperature is thus essential for any interpretation of magnetotelluric data in projecting lithospheric structural models. The measured values of the terrestrial heat flow, radiogenic heat production and thermal conductivity of rocks allow the extrapolation of surface observations to a greater depth and the calculation of the temperature field within the lithosphere. Various methods of deep temperature calculations are presented and discussed. Characteristic geotherms are proposed for major tectonic provinces of Europe and it is shown that the existing temperatures on the crust-upper mantle boundary may vary in a broad interval of 350–1,000°C. The present work is completed with a survey of the temperature dependence of electrical conductivity for selected crustal and upper mantle rocks within the interval 200–1,000°C. It is shown how the knowledge of the temperature field can be used in the evaluation of the deep electrical conductivity pattern by converting the conductivity-versustemperature data into the conductivity-versus-depth data. 相似文献
16.
MT+, Integrating Magnetotellurics to Determine Earth Structure, Physical State, and Processes 总被引：1，自引：0，他引：1
Paul A. Bedrosian 《Surveys in Geophysics》2007,28(2-3):121-167
As one of the few deep-earth imaging techniques, magnetotellurics provides information on both the structure and physical state of the crust and upper mantle. Magnetotellurics is sensitive to electrical conductivity, which varies within the earth by many orders of magnitude and is modified by a range of earth processes. As with all geophysical techniques, magnetotellurics has a non-unique inverse problem and has limitations in resolution and sensitivity. As such, an integrated approach, either via the joint interpretation of independent geophysical models, or through the simultaneous inversion of independent data sets is valuable, and at times essential to an accurate interpretation. Magnetotelluric data and models are increasingly integrated with geological, geophysical and geochemical information. This review considers recent studies that illustrate the ways in which such information is combined, from qualitative comparisons to statistical correlation studies to multi-property inversions. Also emphasized are the range of problems addressed by these integrated approaches, and their value in elucidating earth structure, physical state, and processes. 相似文献
17.
— Simulation of the complete earthquake generation process requires assimilation of observational data on long-term behavior of faults over multiple rupture cycles. Paleoseismology, the study of pre-instrumental earthquakes from geological field investigations, provides the only observations of long-term fault behavior. Paleoseismic data present challenges for assimilation into models because data sets are small, sparse, analog, and contain qualitative uncertainties. Observations can be categorized as primary measurements from field data, or non-primary extrapolations or interpretations of primary data. Assimilation of non-primary data could yield biased simulation results. We present a primary data set for the San Andreas and Imperial faults for comparison with non-primary data in existing databases, and propose standard formats and structure for paleoseismic data assimilation into numerical simulation models . 相似文献
18.
淮北某煤矿采区三维地震勘探地质条件极为复杂,区内褶皱、断层构造发育,常规叠后时间偏移处理很难准确成像,给后期资料解释工作带来不利影响.针对这一问题,采用叠前时间偏移技术,结合煤田地震勘探特点,对影响叠前偏移处理质量的关键步骤（预处理、静校正、叠前去噪、时间域速度模型建立）进行了研究,取得了显著效果.利用叠前偏移数据体解释,最终圆满完成了地质任务.本文通过应用实例,说明了煤田地震勘探资料处理利用叠前时间偏移技术对复杂构造成像效果较好,信噪比提高,断点解释更可靠. 相似文献
19.
Fracture systems can significantly influence productivity in tight sandstone reservoirs. Understanding the in situ fracture network is of importance in exploration and development of such reservoirs. This paper illustrates that stress-strain analysis, based on geological processes, is a credible prediction method for fracture networks and enables an estimation of which fractures are likely to contribute most to flow based on fracture orientation. This study shows the workflow for fracture modelling and its application in a sandstone reservoir using structural validation tools and interactive fracture simulations constrained with lithology, well log and core data. The fracture network model can help us understand not only what a fractured reservoir looks like but also how the existing fracture network behaves. An important consideration is that we need to understand and constrain the geological history to assess the fracture network properly. 相似文献
20.
—?The estimation of realistic seismic input can be obtained from the computation of a wide set of time histories and spectral information, corresponding to possible seismotectonic scenarios for different source and structural models. Such a data set can be very constructively used by civil engineers in the design of new seismo-resistant structures and in the reinforcement of the existing built environment, therefore supplying a particularly powerful tool to the prevention efforts of Civil Defense. The availability of realistic numerical simulations enables us to estimate the amplification effects in complex geological structures exploiting the available geotechnical, lithological, geophysical parameters, topography of the medium, tectonic, historical, paleoseismological data, and seismotectonic models. The realistic modeling of the ground motion is a very important source of knowledge for the preparation of groundshaking scenarios which represent a valid and economical tool in seismic microzonation. 相似文献