共查询到20条相似文献，搜索用时 31 毫秒
1.
煤矿安全生产迫切需要能够对工作面进行实时探测的方法,随采地震成像方法是一个有效解决途径。基于采煤机地震信号特征的分析,研究对比了3种随采地震信号干涉方法的适用性,利用贝叶斯反演提出了工作面的随采地震槽波层析成像方法。结果表明:采用反褶积干涉或互相干干涉,皆能有效压缩震源的子波,得到比互相关干涉更宽频谱的炮集;利用二次干涉方法,有助于获得更高精度的到时与层析成像结果。该方法能够实现煤矿井下回采工作面的随采地震实时成像,及时发现速度随时间变化的危险区域,对工作面地质灾害做出预警。 相似文献
2.
Junji Koyama 《Tectonophysics》1985,118(3-4)
Theoretical study has been made investigating the seismic source spectrum generated from a coherent and incoherent rupture. An earthquake is modeled by a finite propagating rupture on a fault plane where fault heterogeneities, fault patches, are randomly distributed. The dislocation velocity of such a fracture is assumed to be approximated by a stochastic process of random impacts of particles obeying Brownian motion. The parameters of the present stochastic source are seismic moment, fault dimension, fault patch intensity, and patch fracture time. The model predicts two corner frequencies; one originates from the fault finiteness and the other from the fracturing of fault patches. The seismic source spectrum from the model consequently shows distinct frequency dependence of ω0 − ω−2 − ω−γ − ω−2 with increasing angular frequency ω, where γ is about 1.0. The seismic moment is controlled by an average dislocation on the fault and by the fault dimension. The short-period spectrum, which is much more abundant than that of the ordinary deterministic models, is controlled by the product of the fault patch intensity and the square root of their total number. The ω−2 high frequency asymptote of the theoretical spectrum is in conformity with the white acceleration spectrum usually found in the literature, and it guarantees the finite total energy of the rupture process. 相似文献
3.
地质统计学反演技术研究与应用 总被引：1，自引：0，他引：1
实现油气储层的精细描述和建模,是石油勘探和开发过程中十分重要的环节,常规的确定性反演由于受到地震频带限制,反演结果垂向分辨率低,往往难以识别单砂体厚度较小的储层分布。通过在A油田应用的实践表明,应用高密度采集的地震数据,开展基于随机建模技术的地质统计学反演方法,能够有效地综合地质、测井和三维地震数据,明显提高反演结果的垂向分辨率,可以更好地识别薄层砂体,为精细储层识别、油藏建模提供可靠依据。 相似文献
4.
阐述了有色反演的基本原理,并给出了反演流程。通过模型试算,明确有色反演关键参数的物理意义及取值范围,并在孤南洼陷实际工区应用,较好地刻画出沙三下早期低位扇体的横向展布范围。与常规地震属性相比,反演结果更加符合沉积规律,与实钻井岩性分布情况吻合程度高。表明有色反演在保留地震数据原始现象的基础上,分辨率明显提高,适合无井或少井区的地层或岩性解释。 相似文献
5.
The geoacoustic parameters form significant input for underwater acoustic propagation studies and geoacoustic modeling. Conventional
inversion techniques commonly used as indirect approach for extraction of geoacoustic parameters from acoustic or seismic
data are computationally intensive and time-consuming. In the present study, we have tried to exploit the advantage of soft
computing techniques like, reasoning ability of fuzzy logic and learning abilities of neural networks, in inversion studies.
The network model based on the combined approach called adaptive neuro-fuzzy inference system (ANFIS), is found to be very
promising in inversion of the acoustic data. The network model once built is capable of invert a few thousand data sets instantaneously,
to a reasonably good accuracy. In the case of conventional approaches, repetition of the entire inversion process with each
new data set is required. A limited number of sensor’s data are sufficient for simulation of the network model and provides
an advantage to use short hydrophone array data. Inversion results of a few hundred test data sets, representing different
geoacoustic environments, show the prediction error is much less than 0.01 g/cc, 10 m/s, 10 m and 0.1 against first layer’s
density, compressional sound speed, thickness and attenuation respectively for a three-layer geoacoustic model. However, the
error is relatively large for the second- and third-layer parameters, which need to be improved. The model is efficient, robust
and inexpensive. 相似文献
6.
Gianluca Sottili Danilo M. Palladino Biagio Giaccio Paolo Messina 《Mathematical Geosciences》2012,44(5):619-634
Benford’s analysis is applied to the recurrence times of approximately 17,000 seismic events in different geological contexts
of Italy over the last 6 years, including the Mt. Etna volcanic area and the seismic series associated with the destructive
M
w 6.3, 2009 L’Aquila earthquake. A close conformity to Benford’s law and a power-law probability distribution for the recurrence
times of consecutive events is found, as typical of random multiplicative processes. The application of Benford’s law to the
recurrence event times in seismic series of specific seismogenic regions represents a novel approach, which enlarges the occurrence
and relevance of Benford-like asymmetries, with implications on the physics of natural systems approaching a power law behaviour.
Moreover, we propose that the shift from a close conformity of Benford’s law to Brownian dynamics, observed for time separations
among non-consecutive events in the study seismic series, may be ruled by a periodical noise factor, such as the effects of
Earth tides on seismicity tuning. 相似文献
7.
井地联合提取VTI介质各向异性参数 总被引：2，自引：0，他引：2
在新疆塔里木盆地某地区的宽方位三维地震数据中,VTI介质火成岩的各向异性和垂向速度变化引起非双曲线时差。通过对实际资料的系统分析,我们不能利用DMO反演法,移动震源VSP反演法和多偏移距VSP初至旅行时反演法提取Thomsen参数用于各向异性地震资料的处理。因此本文提出一个新的方法:运用地震资料和零偏移距VSP井求取火成岩的各向异性参数δ;在比较精确确定火成岩地层深度和厚度的情况下,利用偏移距VSP井,求取了各向异性参数ε,从而获得火成岩的瞬时各向异性参数η;充分考虑VTI介质垂向速度变化对时差曲线的影响,获得了各向异性参数ηeff。最后,利用所提取的各向异性参数,进行VTI介质各向异性速度分析和成像,成像质量得到明显改善。 相似文献
8.
9.
地质统计学反演及其在吉林扶余油田储层预测中的应用 总被引：3，自引：0，他引：3
地质统计学反演方法将随机建模技术与常规地震反演相结合,有效地综合地质、测井和三维地震数据,可以更加精确地描述储层的变化.在执行地质统计学反演前,首先应用稀疏脉冲约束反演,了解储层的大致分布,以求取子波和水平变差函数.地质统计学反演从井点出发,井间以原始地震数据作为硬数据,通过随机模拟的产生井间波阻抗,然后将波阻抗转换成反射系数,并用确定性反演方法求得的子波褶积产生地震道,通过反复迭代直至合成地震道与原始地震数据达到一定程度的匹配,反演结果是多个等概率的波阻抗数据体实现.反演结果符合输入数据的地质统计学特征并受地质模型的约束,它综合了测井的垂向分辨率高和地震的横向分辨率高的优势,结果的多个实现用于不确定性评价. 相似文献
10.
YanHanjie YanHong LiYunping ZhangXiaofeng 《中国地质大学学报(英文版)》2003,14(3):227-233
As gravity field,magnetic field,electric field and seismic wave field are all physical fields,their object function,reverse function and compound function are certainly infinite contiuously differentiable func-tions which can be expanded into Taylor (Fourier) series within domain of definition and be further reduced in-to solving stochastic distribution function of series and statistic inference of optimal approximation,This is the basis of combined gravity-magnetic-electric-seismic inversion built on the basis of separation of field and source gravity-magnetic difference-value(D-value)trend surface,taking distribution-independent fault sys-tem as its unit,depths of seismic and electric interfaces of interests as its corresponding bivariate compound re-verse function of gravity-magnetic anomalies and using high order polynomial(high order trigonometric func-tion)approximating to its series distribution,The difference from current dominant inversion techniques is that,first,it does not respectively create gravity-seismic,magnetic-seismic deterministic inversion model from theoretical model,but combines gravity-magnetic-electric-seismic stochastic inversion model from stochastic model;second,after the concept of equivalent geological body being introduced,using feature of independent variable of gravity-magnetic field functions,taking density and susceptibility related to gravity-magnetic func-tion as default parameters of model,the deterministic model is established owing to better solution to the con-tradictioc of difficulty in identifying strata and less test analytical data for density and susceptibility in newly explored area;third,under assumption of independent parent distribution,a real modeling by strata,the prob-lem of difficult plane closure arising in profile modeling is avoided,This technology has richer and more detailed fault and strata information than sparse pattern seismic data in newly explored area,successfully inverses and plots structural map of Indosinian discontinuty in Hefei basin with combined gravity-magnetic-electric-seismic inversion,With development of high precision gravity-magnetic and overall geophysical technology,it is certain for introducing new methods of stochastic modeling and computational intelligence and promoting the develop-ment of combined gravity-magnetic-electric-seismic inversion to open a new substantial and promoting the develop-ment of combined gravity-magnetic-electric-seismic inversion to open a new substantial path. 相似文献
11.
The existence of gas-hydrates in marine sediments increases the seismic velocity, whereas even a small amount of underlying
free-gas reduces the velocity considerably. The change in velocities against the background (without gas-hydrates and free-gas)
velocity can be used for identification and assessment of gas-hydrates. Traveltime inversion of identifiable reflections from
large offset multi channel seismic (MCS) experiment is an effective method to derive the 2-D velocity structure in an area.
We apply this method along a seismic line in the Kerala-Konkan (KK) offshore basin for delineating the gas-hydrates and free-gas
bearing sediments across a bottom simulating reflector (BSR). The result reveals a four layer 2-D shallow velocity model with
the topmost sedimentary layer having velocity of 1,680–1,740 m/s and thickness of 140–190 m. The velocity of the second layer
of uniform thickness (110 m) varies from 1,890 to 1,950 m/s. The third layer, exhibiting higher velocity of 2,100–2,180 m/s,
is interpreted as the gas-hydrates bearing sediment, the thickness of which is estimated as 100 to 150 m. The underlying sedimentary
layer shows a reduction in seismic velocity between 1,620 to 1,720 m/s. This low-velocity layer with 160–200 m thickness may
be due to the presence of free-gas below the gas-hydrates layer. 相似文献
12.
《International Geology Review》2012,54(12):1073-1086
The geologic structure of the Earth's upper crust can be revealed by modeling variation in seismic arrival times and in potential field measurements. We demonstrate a simple method for sequentially satisfying seismic traveltime and observed gravity residuals in an iterative 3-D inversion. The algorithm is portable to any seismic analysis method that uses a gridded representation of velocity structure. Our technique calculates the gravity anomaly resulting from a velocity model by converting to density with Gardner's rule. The residual between calculated and observed gravity is minimized by weighted adjustments to the model velocity-depth gradient where the gradient is steepest and where seismic coverage is least. The adjustments are scaled by the sign and magnitude of the gravity residuals, and a smoothing step is performed to minimize vertical streaking. The adjusted model is then used as a starting model in the next seismic traveltime iteration. The process is repeated until one velocity model can simultaneously satisfy both the gravity anomaly and seismic traveltime observations within acceptable misfits. We test our algorithm with data gathered in the Puget Lowland of Washington state, USA (Seismic Hazards Investigation in Puget Sound [SHIPS] experiment). We perform resolution tests with synthetic traveltime and gravity observations calculated with a checkerboard velocity model using the SHIPS experiment geometry, and show that the addition of gravity significantly enhances resolution. We calculate a new velocity model for the region using SHIPS traveltimes and observed gravity, and show examples where correlation between surface geology and modeled subsurface velocity structure is enhanced. 相似文献
13.
14.
南极和北极地区在全球变化中的作用研究 总被引：15，自引：0，他引：15
多次波问题是海洋地震勘探中最突出的问题之一 ,如何有效地压制多次波是解决问题的关键。多次波数据处理的压制方法和技术分为运动学的滤波方法和动力学的波动方程方法两大类。波动方程方法由于几乎不需要先验信息和具有较好的压制效果 ,已经成为多次波压制方法和技术发展的主要趋势。文章首先对波动方程方法进行了较全面的综述 ;然后 ,对波动方程方法中的反馈迭代反演方法做了深入的讨论 ;最后 ,通过理论模型的正反演计算 ,验证了运用波动方程反馈迭代反演法不需要知道震源函数、地下岩层结构和岩性等先验信息。此方法适用于压制多种类型的多次波 ,具有优异的振幅保真性等独特的优点。 相似文献
15.
建立准确的低频模型是波阻抗反演中的重要环节,它直接影响着波阻抗反演结果的准确性。但是,常规模型建立方法的准确性受钻井数量影响明显,钻井数量越多,模型的准确性越高。在海洋深水油气勘探过程中,由于勘探费用昂贵,钻井数量非常少,很难通过常规方法建立准确的低频模型。特别是在沉积体横向特征变化较大时,地震反演的可靠性受到巨大影响。本文首先介绍了立体层析速度反演的基本理论和数据域、成像域立体层析速度反演的计算过程,综合数据域立体层析与成像域立体层析的优势获得了高精度速度模型;然后结合有限的钻井进行标定,构建出地震反演所需的低频模型,有效提升了低频模型的精度,使其达到可真实反映较大规模地质异常体的尺度;最后,将其应用于南海深水区W构造的勘探实践,提升了反演结果横向预测的准确性。 相似文献
16.
阻抗反演是利用波阻抗与介电常数关系开展地下介质参数估计的重要技术,在探地雷达以及叠后地震资料解释中具有广泛的应用。常规阻抗反演需要钻孔或测井曲线作为约束项,约束项信息直接影响阻抗反演的估计精度。在缺少钻孔数据的实际应用中,如何开展探地雷达阻抗反演是该方法研究的重要内容之一。基于上述问题,本文提出了基于速度分析的探地雷达阻抗反演方法。其基本思想是基于多偏移距雷达数据开展速度谱分析和Dix反演,以获得不同深度的速度信息作为阻抗反演的约束项;同时,采用K-means方法自动拾取速度谱信息,大大降低了常规人工拾取误差,提高了计算效率。通过典型随机土壤介质模型,验证了本文方法在无钻孔条件下仍然可以获得较好的介电常数估计结果,并测试噪声适应能力强。最后通过美国密歇根州Wurtsmith AFB,in Oscoda区域的探地雷达数据测试了本文提出方法在探地雷达实测数据参数估计中具有较好的应用效果。 相似文献
17.
为了适当地完成储层表征的过程,一个有效的方法就是把现场所有可以利用的信息融合成一个一致性的模型。在实际生产中实现这种融合并非简单的任务,所以有必要运用如地震反演等特殊方法。应用地震反演可以使测井数据和地震数据的有效结合成为可能,并且可以得到一个模型,该模型在预测过程中可通过流体数字模拟来验证。地震反演可以通过多种方法进行,主要分为两大类:一类是确定性方法(其代表是回归反演和约束稀疏脉冲反演),另一类是随机方法(其代表是地质统计学反演)。在本次研究中,通过随机反演结果和确定性反演结果的对比展示了随机反演是如何改进储层表征过程的。事实上,随机反演,可以运用较高的采样率(和储层模型的网格大小相接近),来产生一个更可靠的模型。随机反演的另一个好处就是随机方法可产生一些基本的统计测量值来改进解释精度,并且在储层表征过程中能生成大量的实现,从而使储层模型的不确定性研究成为可能。 相似文献
18.
Knowledge of seismic active earth pressure behind rigid retaining wall is very important. In this paper, the pseudo-dynamic
approach, which considers the effect of both compression and shear wave propagation, is adopted to calculate the seismic active
force supporting c-Φ backfill. Considering a planar rupture surface, the effect of wide range of parameters like inclination of retaining wall,
wall friction and soil friction angle, shear wave and compression wave velocity, horizontal and vertical seismic coefficients
are taken into account to evaluate the seismic active force. Results are presented in terms of seismic coefficients in tabular
form and variation of pressure with depth. 相似文献
19.
Igor Beresnev 《Natural Hazards》2013,66(2):1287-1291
The corner frequency of the spectrum of particle acceleration in a seismic wave radiated by an earthquake source marks the transition between the low-frequency band, in which the spectrum rises as frequency squared, and the high-frequency band, in which the spectrum is flat. These two distinct bands are controlled by different characteristics of faulting. The low-frequency range is governed by the value of slip alone, while the high-frequency range is controlled by both the total slip and slip velocity. This distinction explains why inversions of geodetic and shorter-period seismic data sense different characteristics of source process and are not generally comparable. Neglect of the sensitivity of seismic data to both slip and its rate may lead to false images of the inverted slip on the fault, as these characteristics trade off with each other. A recent example of the 2011 M w 9.0 Tohoku-oki, Japan, earthquake demonstrates that the observed “frequency-dependent” variations in the rupture process over the fault plane should not be considered unique to this particular event but rather a natural consequence of the frequency-dependent inversion. 相似文献
20.
Dali Zhang Michael P. Lamoureux Gary F. Margrave Elena Cherkaev 《Computational Geosciences》2011,15(1):117-133
The article presents a numerical inversion method for estimation of quality Q factor and phase velocity in linear, viscoelastic, isotropic media using reconstruction of relaxation spectrum from measured
or computed complex velocity or modulus of the medium. Mathematically, the problem is formulated as an inverse problem for
reconstruction of relaxation spectrum in the analytic Stieltjes representation of the complex modulus using rational approximation.
A rational (Padé) approximation to the relaxation spec trum is derived from a constrained least squares minimization problem
with regularization. The recovered stress-strain relaxation spectrum is applied to numerical calculation of frequency-dependent
Q factor and frequency-dependent phase velocity for known analytical models of a standard linear viscoelastic solid (Zener)
model as well as a nearly constant-Q model which has a continuous spectrum. Numerical results for these analytic models show good agreement between theoretical
and predicted values and demonstrate the validity of the algorithm. The proposed method can be used for evaluating relaxation
mechanisms in seismic wavefield simulation of viscoelastic media. The constructed lower order Padé approximation can be used
for determination of the internal memory variables in time-domain finite difference numerical simulation of viscoelastic wave
propagation. 相似文献