scholarly journals Q FACTOR ESTIMATION FROM SURFACE AND VSP SEISMIC DATA: A NUMERICAL MODELING STUDY

2013 ◽  
Vol 31 (4) ◽  
pp. 683 ◽  
Author(s):  
Adalto Oliveira Da Silva ◽  
Roseane Marchezi Misságia ◽  
Marco Antonio Rodrigues Ceia
Keyword(s):  
Numerical Modeling ◽  
Seismic Data ◽  
Seismic Waves ◽  
Numerical Models ◽  
Petroleum Industry ◽  
Seismic Signal ◽  
Petroleum Reservoir ◽  
Seismic Characterization ◽  
Vsp Data ◽  
Saturation Effects

ABSTRACT. Seismic acquisition is used by the petroleum industry to identify subsurface structures that meet pre-established requirements for hydrocarbon accumulation. In mature fields, such surveys are important to monitor the reserves, the producing wells and to aid the development of projects for new wells location. This work proposes a processing workflow that seeks to improve the high frequency content of the seismic signal, which is the most attenuated part of the frequency spectrum of such kind of signal, especially in surface seismic data. The method is based on the calculation ofQ factor from VSP data which allows defining an inverse Qef filter to be applied in surface seismic data. This processing flow was tested in two datasets derived from numerical models: one with plain-parallel layers and another representing the wedge type reservoir. Such numerical modeling aimed to simulate the attenuation of the seismic signal concerning the geometry and saturation effects in those two reservoir models, which allows testing the efficiency of the inverse Qef filter that was designed to mitigate energy loss effects in seismic waves used for reservoir characterization.Keywords: attenuation coefficient, quality factor, seismic characterization, petroleum reservoir. RESUMO. A aquisição sísmica é utilizada pela indústria do petróleo com a finalidade de identificar em subsuperfície estruturas que satisfaçam os requisitos pré estabelecidos para acumulação de hidrocarbonetos. Em campos maduros, tais levantamentos são importantes para monitorar reservas, poços produtores e desenvolver novos projetos de poço. Nesse artigo propõe-se um fluxo de processamento voltado para o melhoramento das altas frequências atenuadas nos dados sísmicos de superfície. Isto será feito a partir do cálculo do fator Q utilizando dados sísmicos de poço para definir um filtro inverso Qef e realizar a filtragem de dados sísmicos de superfície. Este fluxo foi testado em dois conjuntos de dados provenientes de simulações numéricas: com camadas planas e paralelas, e outro com camadas inclinadas simulando a borda acunhada (wedge) de um reservatório delgado. A modelagem numérica teve como propósito simular a atenuação do sinal sísmico associado aos efeitos da geometria e saturação nos dois tipos de reservatórios, possibilitando testar a eficácia do filtro inverso Qef proposto para mitigar os efeitos da perda de energia da onda sísmica na caracterização de reservatórios de hidrocarbonetos.Palavras-chave: coeficiente de atenuação, fator de qualidade, caracterização sísmica, reservatório de petróleo.

Integrating multigeophysical data to improve structural imaging in the Dayangshu Basin

2020 ◽  
Vol 8 (4) ◽  
pp. SS87-SS96
Author(s):  
Bo Yang ◽  
Zhan Liu ◽  
Kaijun Xu
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Volcanic Rocks ◽  
Seismic Signal ◽  
Gravity Inversion ◽  
Structural Constraints ◽  
Structural Imaging ◽  
Geophysical Model ◽  
Resistivity Model ◽  
Geologic Model

We have used the integrated interpretation of gravity, magnetotelluric (MT) data, and seismic data to improve the structural imaging of the Dayangshu Basin. The Dayangshu Basin is mainly composed of clastic and volcanic rocks. The logging data in the basin show different degrees of direct hydrocarbon indication, suggesting that the Dayangshu Basin has good potential for exploration. However, the widely distributed volcanic rocks attenuate seismic waves and lead to poor seismic imaging. Thus, the seismic signal is weak in the Ganhe Formation (K1g) and reliable seismic images cannot be obtained below that formation. MT data can accurately obtain images of deep structures because the resistivity of volcanic rocks is significantly higher than that of sedimentary rocks. Therefore, to obtain a more reliable geologic model, we combine the traditional 3D MT inversion result with logging and seismic data to establish an initial model. The 3D MT fuzzy constrained inversion (FCI) produces a more reliable geophysical model and geologically meaningful results. The resistivity model inverted from FCI shows that volcanic rocks are widely distributed in the Ganhe Formation, and the resistivity value of the lower section of the Longjiang Formation is greater than that of the upper section of the Longjiang Formation. Finally, the 3D gravity inversion with structural constraints from 3D MT FCI method was performed to improve the model resolution in depth and to highlight the density variations within the Jiufengshan Formation, which can further optimize the geologic model. We have determined how the effective integration of gravity, MT, and seismic data can improve the structural imaging of the Dayangshu Basin.

Simulation Research on Synthesis Algorithm of Directional Illumination Data

2011 ◽  
Vol 403-408 ◽  
pp. 2337-2340
Author(s):  
Shu Cong Liu ◽  
Yan Xing Song ◽  
Jing Song Yang
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Seismic Analysis ◽  
Signal To Noise Ratio ◽  
A Priori ◽  
Effective Means ◽  
Seismic Signal ◽  
Geological Structure ◽  
Seismic Exploration ◽  
The Impact

Seismic illumination analysis was an effective means of recognizing and studying the energy distributions in the underground geological structure in seismic data acquisition. Effective seismic illumination analysis to a priori targeted-geological model to identify the energy distribution of seismic waves, can apply to seismic analysis and amplitude compensation analysis. To increase the signal to noise ratio and resolution of seismic data when vibrator seismic exploration, it was necessary to strengthen the energy of a certain direction to get the High-Precision imaging and the best illumination of the target areas.Simulation research were done on single source directional illumination seismic technology, with seismic illumination analysis, and the impact of source number, spacing change on directional illumination seismic technology were also analyzed. Simulation results showed that the directional seismic technology could improved SNR of seismic data, and could be used for seismic signal processing.

Investigating the seismic imaging of faults using PS data from the Snøhvit field, Barents Sea, and forward seismic modelling 

2021 ◽  
Author(s):  
Jennifer Cunningham ◽  
Wiktor Weibull ◽  
Nestor Cardozo ◽  
David Iacopini
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Seismic Waves ◽  
Barents Sea ◽  
Incidence Angle ◽  
Seismic Signal ◽  
Fault Zones ◽  
Seismic Modelling ◽  
Systematic Improvement

<p>PS seismic data from the Snøhvit field are compared with forward seismic modelling to understand the effect of azimuthal separation and incidence angle on the imaging of faults. Two faults, one oriented oblique to the survey and one approximately parallel to the survey were chosen. Azimuthally separated W (source is W relative to receivers) and E (source E relative to receivers) data demonstrate that fault imaging is more affected by azimuth when the faults are oblique to the survey orientation, and W data image the faults better. Partial stack data show that with increasing incidence angle there is a systematic improvement in the quality of fault imaging in both the E and W data. In addition, the frequency content of seismic waves back-scattered from within and around fault zones is analysed in the Snøhvit data. Low-medium frequencies are dominant within fault zones, compared with higher frequencies in adjacent areas and haloes of medium frequencies surrounding the faults. Two synthetic experiments support the azimuth, incidence angle and frequency observations. In the first experiment, the fault is modelled as a planar discontinuity and the data were processed in the same way as the Snøhvit data (into separate azimuths and incidence angle stacks). The first experiment confirms a strengthening in the seismic signal from faults in the W data. This is due to the interaction of specular waves and diffractions which are more abundant in the W data. The second experiment had three parts modelling the fault zone with different layering complexity. It proved that frequencies in the fault and adjacent areas increase with fault zone complexity, and that the internal architecture of faults can impact the frequencies in the data adjacent to faults. </p>

ESTIMATION OF QUALITY FACTOR Q FROM THE INSTANTANEOUS FREQUENCY AT THE ENVELOPE PEAK OF A SEISMIC SIGNAL

2011 ◽  
Vol 19 (02) ◽  
pp. 155-179 ◽  
Author(s):  
JINGHUAI GAO ◽  
SENLIN YANG ◽  
DAXING WANG ◽  
RUSHAN WU
Keyword(s):  
Travel Time ◽  
Quality Factor ◽  
Instantaneous Frequency ◽  
Seismic Data ◽  
Approximate Equation ◽  
Spectral Ratio ◽  
Seismic Signal ◽  
Vsp Data ◽  
Zero Offset ◽  
Quality Factor Q

In this paper, we derive an approximate equation combining the quality factor Q, the travel time of a wave, and the variation of the instantaneous frequency (IF) at the envelope peaks of two successive seismic wavelets, along the wave-propagating direction, based on the theory of one-way wave propagation in a 1D viscoelastic medium. We then propose a method (called the WEPIF method) to estimate Q by measuring the variations of the wavelet envelope peak IF (WEPIF) with the travel time of seismic wavelet. For zero-offset VSP data and poststack seismic data, we describe how to implement the WEPIF method in detail. A test on synthetic VSP data shows that the WEPIF method is less sensitive to interference from the reflector than the logarithm spectral ratio and the centroid frequency shift methods. Applied to field VSP data, the WEPIF method gives a Q-curve with nearly the same distribution as the results from a known well. Applied to poststack seismic data, it produces a Q-profile that indicates an intense absorption zone corresponding to the excellent gas-bearing reservoir. This allows us to predict a potential high-productivity gas well. Drilling confirmed this prediction. The WEPIF method can be applied to poststack seismic data and zero-offset VSP data.

Seismic inversions of large, rapid landslides: what they can and cannot tell us about event dynamics

2021 ◽  
Author(s):  
Kate Allstadt ◽  
Andrew Mitchell ◽  
Liam Toney ◽  
David George ◽  
Scott McDougall
Keyword(s):  
Seismic Data ◽  
Seismic Waves ◽  
Numerical Models ◽  
Seismic Inversion ◽  
Two Phase ◽  
Flow Equations ◽  
Long Period ◽  
Wide Range ◽  
Regularization Techniques ◽  
Event Dynamics

<p>Researchers are increasingly incorporating force histories derived from long-period seismic waves into multidisciplinary studies of large, rapid landslides. The force history can provide important information about what happened during failure — information that complements data available from field investigations and remote sensing analyses. It can also provide additional constraints on the dynamics of landslide motion than can be used to validate and/or calibrate numerical landslide models. However, the inversions need to be of high quality and must be interpreted properly. Because this technique is relatively new, we are still discovering how to best conduct inversions to obtain robust results and how to appropriately interpret these results. In this study, we run numerical models of landslides with idealized source and path geometries using two different modeling packages, DAN3D and D-Claw, and we use the model outputs to generate synthetic long-period seismic data. Both models use depth-averaged flow equations over 3D topography, with DAN3D using semi-empirical material rheologies and D-Claw using a two-phase granular and fluid flow approach. To examine the influence of station azimuthal coverage and distance, we synthesize seismic data for a wide range of possible station configurations. We then use these synthetic seismic data to conduct seismic inversions using the recently released open-source Python-based software package, lsforce (https://code.usgs.gov/ghsc/lhp/lsforce). In doing these inversions, we add differing levels and types of noise, vary the inversion options (e.g., frequency range, regularization techniques) and then compare the results to the “known” dynamics of the modeled idealized landslides. We aim to understand common artefacts, limitations, and other potential pitfalls in interpretation, to guide the inversion process in future studies. We repeat this process for idealized landslides of increasing complexity, including multi-part failures, sinuous paths, and gradual versus sudden initiations, to simulate how these characteristics are reflected in the force history and to better understand what level of detail can be constrained from the seismic inversion. This work will help guide researchers to obtain more reliable information about landslide dynamics from seismic inversions in future landslide studies.</p>

scholarly journals Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 458
Author(s):  
Drew C. Baird ◽  
Benjamin Abban ◽  
S. Michael Scurlock ◽  
Steven B. Abt ◽  
Christopher I. Thornton
Keyword(s):  
Numerical Modeling ◽  
Physical Model ◽  
Numerical Models ◽  
Hydraulic Performance ◽  
Physical Models ◽  
Protection Measures ◽  
Design Engineers ◽  
Model Study ◽  
Study Results ◽  
Wide Range

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

Reconstruction of the Reservoir Fine Structure by Using Scattering Attributes

2021 ◽  
Author(s):  
Vladimir Cheverda ◽  
Vadim Lisitsa ◽  
Maksim Protasov ◽  
Galina Reshetova ◽  
Andrey Ledyaev ◽  
...  
Keyword(s):  
Seismic Data ◽  
Numerical Experiments ◽  
Seismic Waves ◽  
Fractured Reservoirs ◽  
Three Dimensional ◽  
Geological Structure ◽  
Discrete Elements ◽  
Digital Twin ◽  
The North ◽  
Slip Surfaces

Abstract To develop the optimal strategy for developing a hydrocarbon field, one should know in fine detail its geological structure. More and more attention has been paid to cavernous-fractured reservoirs within the carbonate environment in the last decades. This article presents a technology for three-dimensional computing images of such reservoirs using scattered seismic waves. To verify it, we built a particular synthetic model, a digital twin of one of the licensed objects in the north of Eastern Siberia. One distinctive feature of this digital twin is the representation of faults not as some ideal slip surfaces but as three-dimensional geological bodies filled with tectonic breccias. To simulate such breccias and the geometry of these bodies, we performed a series of numerical experiments based on the discrete elements technique. The purpose of these experiments is the simulation of the geomechanical processes of fault formation. For the digital twin constructed, we performed full-scale 3D seismic modeling, which made it possible to conduct fully controlled numerical experiments on the construction of wave images and, on this basis, to propose an optimal seismic data processing graph.

About this title - Seismic Characterization of Carbonate Platforms and Reservoirs

10.1144/sp509 ◽  
2021 ◽  
Vol 509 (1) ◽  
pp. NP-NP
Author(s):  
J. Hendry ◽  
P. Burgess ◽  
D. Hunt ◽  
X. Janson ◽  
V. Zampetti
Keyword(s):  
Seismic Data ◽  
Oil And Gas ◽  
Carbonate Platform ◽  
Carbonate Platforms ◽  
Oil And Gas Exploration ◽  
Seismic Modelling ◽  
Flow Units ◽  
Development Data ◽  
Seismic Characterization

Modern seismic data have become an essential toolkit for studying carbonate platforms and reservoirs in impressive detail. Whilst driven primarily by oil and gas exploration and development, data sharing and collaboration are delivering fundamental geological knowledge on carbonate systems, revealing platform geomorphologies and how their evolution on millennial time scales, as well as kilometric length scales, was forced by long-term eustatic, oceanographic or tectonic factors. Quantitative interrogation of modern seismic attributes in carbonate reservoirs permits flow units and barriers arising from depositional and diagenetic processes to be imaged and extrapolated between wells.This volume reviews the variety of carbonate platform and reservoir characteristics that can be interpreted from modern seismic data, illustrating the benefits of creative interaction between geophysical and carbonate geological experts at all stages of a seismic campaign. Papers cover carbonate exploration, including the uniquely challenging South Atlantic pre-salt reservoirs, seismic modelling of carbonates, and seismic indicators of fluid flow and diagenesis.

scholarly journals Numerical modeling of seismic waves by discontinuous spectral element methods

2018 ◽  
Vol 61 ◽  
pp. 1-37 ◽  
Author(s):  
Paola F. Antonietti ◽  
Alberto Ferroni ◽  
Ilario Mazzieri ◽  
Roberto Paolucci ◽  
Alfio Quarteroni ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Discontinuous Galerkin ◽  
Large Scale ◽  
Seismic Waves ◽  
Spectral Element ◽  
Fully Discrete ◽  
Time Marching ◽  
Space Discretization ◽  
Large Earthquakes

We present a comprehensive review of Discontinuous Galerkin Spectral Element (DGSE) methods on hybrid hexahedral/tetrahedral grids for the numerical modeling of the ground motion induced by large earthquakes. DGSE methods combine the exibility of discontinuous Galerkin meth-ods to patch together, through a domain decomposition paradigm, Spectral Element blocks where high-order polynomials are used for the space discretization. This approach allows local adaptivity on discretization parameters, thus improving the quality of the solution without affecting the compu-tational costs. The theoretical properties of the semidiscrete formulation are also revised, including well-posedness, stability and error estimates. A discussion on the dissipation, dispersion and stability properties of the fully-discrete (in space and time) formulation is also presented. Here space dis-cretization is obtained based on employing the leap-frog time marching scheme. The capabilities of the present approach are demonstrated through a set of computations of realistic earthquake scenar-ios obtained using the code SPEED (http://speed.mox.polimi.it), an open-source code specifically designed for the numerical modeling of large-scale seismic events jointly developed at Politecnico di Milano by The Laboratory for Modeling and Scientific Computing MOX and by the Department of Civil and Environmental Engineering.

scholarly journals Numerical modeling of the hydraulic impact of riparian vegetation

2018 ◽  
Vol 44 ◽  
pp. 00194
Author(s):  
Krzysztof Wolski ◽  
Tomasz Tymiński ◽  
Grzegorz Chrobak
Keyword(s):  
Numerical Modeling ◽  
Riparian Vegetation ◽  
Water Surface ◽  
Numerical Models ◽  
Three Dimensional ◽  
Careful Examination ◽  
Impact Structure ◽  
Hydraulic Impact ◽  
Vegetation Zones ◽  
Maximal Shear Stress

This paper presents results of numerical modelling of riverbed segment with riparian vegetation performed with use of CCHE2 software. Vegetation zones are places where dynamic of water flow increases. Therefore, there is a need of careful examination of hydraulic impact structure of such zones. Accurate research is necessary and should be performed with use of physical or numerical models, two or three dimensional. Paper presents distribution of velocity and area of water surface for two variants of vegetation deposition acquired in CCHE2D software and modelled for riverbed with distinctive riparian vegetation. Results point to significant (30–40%) increase of maximal velocities in riverbed with riparian vegetation, while directly near the vegetation there were zones with very low velocities. Local damming occurs before vegetal zone. Maximal shear stress in zones with increased velocity is significantly augmented compared to conditions with no vegetation, which can cause more intensive erosion in those zones

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