Widely linear denoising of multicomponent seismic data     

Breno Bahia  Mauricio D. Sacchi 《Geophysical Prospecting》2020,68(2):431-445

Seismic data processing is a challenging task, especially when dealing with vector-valued datasets. These data are characterized by correlated components, where different levels of uncorrelated random noise corrupt each one of the components. Mitigating such noise while preserving the signal of interest is a primary goal in the seismic-processing workflow. The frequency-space deconvolution is a well-known linear prediction technique, which is commonly used for random noise suppression. This paper represents vector-field seismic data through quaternion arrays and shows how to mitigate random noise by proposing the extension of the frequency-space deconvolution to its hypercomplex version, the quaternion frequency-space deconvolution. It also shows how a widely linear prediction model exploits the correlation between data components of improper signals. The widely linear scheme, named widely-linear quaternion frequency-space deconvolution, produces longer prediction filters, which have enhanced signal preservation capabilities shown through synthetic and field vector-valued data examples.  相似文献   

A numerical study on deblending of land simultaneous shooting acquisition data via rank-reduction filtering and signal enhancement applications     

Woodon Jeong  Constantinos Tsingas  Mohammed S. Almubarak 《Geophysical Prospecting》2020,68(6):1742-1757

We propose a workflow of deblending methodology comprised of rank-reduction filtering followed by a signal enhancing process. This methodology can be used to preserve coherent subsurface reflections and at the same time to remove incoherent and interference noise. In pseudo-deblended data, the blending noise exhibits coherent events, whereas in any other data domain (i.e. common receiver, common midpoint and common offset), it appears incoherent and is regarded as an outlier. In order to perform signal deblending, a robust implementation of rank-reduction filtering is employed to eliminate the blending noise and is referred to as a joint sparse and low-rank approximation. Deblending via rank-reduction filtering gives a reasonable result with a sufficient signal-to-noise ratio. However, for land data acquired using unconstrained simultaneous shooting, rank-reduction–based deblending applications alone do not completely attenuate the interference noise. A considerable amount of signal leakage is observed in the residual component, which can affect further data processing and analyses. In this study, we propose a deblending workflow via a rank-reduction filter followed by post-processing steps comprising a nonlinear masking filter and a local orthogonalization weight application. Although each application shows a few footprints of leaked signal energy, the proposed combined workflow restores the signal energy from the residual component achieving significantly signal-to-noise ratio enhancement. These hierarchical schemes are applied on land simultaneous shooting acquisition data sets and produced cleaner and reliable deblended data ready for further data processing.  相似文献   

Spatially constrained attenuation compensation in the mixed domain     

Xiong Ma  Guofa Li  Shumei He  Hao Li  Zhewu Wang 《Geophysical Prospecting》2020,68(6):1819-1833

Seismic attenuation compensation is a spectrum-broadening technique for enhancing the resolution of non-stationary seismic data. The single-trace attenuation compensation algorithms ignore the prior information that the seismic reflection events are generally continuous along seismic traces, thus, the compensated result may have poor spatial continuity and low signal-to-noise ratio. To address this problem, we extend the single-trace approaches to the multi-trace algorithms and furthermore propose a multi-trace attenuation compensation with a spatial constraint. The frequency-space prediction filters are the key to construct this spatial regularization. We test the effectiveness of the proposed spatially constrained attenuation compensation algorithm by applying both synthetic and field data examples. Synthetic data tests indicate that the proposed multi-trace attenuation compensation approach can provide a better compensated result than single-trace attenuation compensation algorithm in terms of suppressing noise amplification and guaranteeing structural continuities. Field data applications further confirm its stability and practicality to improve seismic resolution.  相似文献   

Windowless Q-factor tomography by the instantaneous frequency     

A. Vesnaver  G. Böhm  P. Cance  M. Dal Cin  D. Gei 《Geophysical Prospecting》2020,68(9):2611-2636

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.  相似文献   

Improved structural interpretation of legacy 3D seismic data from Karee platinum mine (South Africa) through the application of novel seismic attributes     

Musa S.D. Manzi  Gordon R.J. Cooper  Alireza Malehmir  Raymond J. Durrheim 《Geophysical Prospecting》2020,68(1):145-163

Seismic detection of faults, dykes, potholes and iron-rich ultramafic pegmatitic bodies is of great importance to the platinum mining industry, as these structures affect safety and efficiency. The application of conventional seismic attributes (such as instantaneous amplitude, phase and frequency) in the hard-rock environment is more challenging than in soft-rock settings because the geology is often complex, reflections disrupted and the seismic energy strongly scattered. We have developed new seismic attributes that sharpen seismic reflections, enabling additional structural information to be extracted from hard-rock seismic data. The symmetry attribute is based on the invariance of an object with respect to transformations such as rotation and reflection; it is independent of the trace reflection amplitude, and hence a better indicator of the lateral continuity of thin and weak reflections. The reflection-continuity detector attribute is based on the Hilbert transform; it enhances the visibility of the peaks and troughs of the seismic traces, and hence the continuity of weak reflections. We demonstrate the effectiveness of these new seismic attributes by applying them to a legacy 3D seismic data set from the Bushveld Complex in South Africa. These seismic attributes show good detection of deep-seated thin (∼1.5 m thick) platinum ore bodies and their associated complex geological structures (faults, dykes, potholes and iron-rich ultramafic pegmatites). They provide a fast, cost-effective and efficient interpretation tool that, when coupled with horizon-based seismic attributes, can reveal structures not seen in conventional interpretations.  相似文献   

数字天气雷达虚拟终端的硬件和软件设计     

赵坤  陈建军  方德贤  葛文忠  慕熙昱 《高原气象》2006,25(2):335-343

设计了一套基于PC机的数字天气雷达虚拟终端系统,用普通的PC机代替传统数字天气雷达信号处理分机[1,2]直接完成雷达信号处理和实时显示。该系统在硬件方面,设计了基于PCI总线的三通道高速数据接收卡,以满足大容量数据高速传输要求;在软件方面则利用高级语言(C )和虚拟设备驱动程序(WDM)技术开发了一套基于WINDOWS2000/9X操作系统的实时处理软件,以此控制数据接收卡和雷达工作,并完成信号处理和实时显示。实际应用表明,该系统结构简单、界面友好、操作方便、便于升级,完全能够实时、高效地处理常规天气雷达信号,而且处理后的雷达回波层次清楚,具有较高精度。本研究也为虚拟终端应用到多普勒天气雷达打下了一个良好的基础。  相似文献   

SSR在心肌重构过程中的表达改变     

肖杨  吴青青  唐其柱 《寒旱区科学》2017,9(5):124-127

目的 探讨SSR在心肌重构过程中的表达改变。方法 采用冠状动脉左前降支结扎术建立小鼠心肌梗死后的心肌重构模型、异丙肾上腺素（ISO）皮下注射2周建立小鼠急性心脏损伤模型;胸主动脉结扎术（aortic banding,AB）建立小鼠心肌肥厚的模型。采用RT-PCR检测各种心肌重构模型中SSR转录水平的改变。结果 SSR亚单位1（SSR1）和3（SSR3）在小鼠心肌梗死（miocardial infarction,MI）术后2周表达明显降低（P<0.05）;在ISO诱导的急性心脏损伤后2周表达降低（P<0.05）;在AB术后1周表达降低（P<0.05）。然而SSR1和SSR3的表达在AB术后2周开始增高（P<0.05）,持续到AB术后8周（P<0.05）。结论 SSR1和SSR3的表达在不同模型的心肌重构中均发生明显改变,且呈现动态变化,提示其可能参与心肌重构的发生、发展。  相似文献   

太平洋次表层海温异常年际变率的信号通道与ENSO循环   总被引：1，自引：1，他引：0  

陈永利  李琦  赵永平  王凡 《海洋与湖沼》2010,41(5):657-666

利用SODA海洋同化资料,分析了太平洋次表层海温异常(SOTA)年际信号变异特征与ENSO循环的联系。结果表明,热带太平洋的年际变率表现为以160°W为纵轴的东西向和以6°—8°N为横轴的南北向的跷跷板分布,南太平洋和北太平洋中高纬度海洋的SOTA则与热带西太平洋SOTA同号,但强度较弱,这些变化都与ENSO事件密切相关,是ENSO事件的两个主要模态,具57和44个月显著周期。ENSO循环期间,热带西太平洋SOTA强信号中心沿赤道东传,到达赤道东太平洋后加强并北扩,导致ElNi?o或LaNi?a事件,同时从热带西太平洋有较弱SOTA信号向东北和西南传播,在南、北太平洋中高纬度海域产生弱SOTA;同期位于热带东太平洋反号的SOTA强信号中心沿10°—15°N(平均12°N)西传,至热带西太平洋后加强并南扩,为下次LaNi?a或ElNi?o事件准备条件,同时在北太平洋中高纬度海洋还存在着反号弱的SOTA。如此周而复始,完成ENSO循环。太平洋次表层海温年际变化信号除在赤道及以北的热带太平洋存在一个逆时针方向的传播通道外,同时在热带西太平洋有异常信号向南、北太平洋中高纬度海域传播,并指出ENSO循环期间太平洋次表层海温异常年际变率信号传播的可能通道。  相似文献