Special section on azimuthal dependence of P-wave seismic signatures—Introduction

Geophysics ◽  
1999 ◽  
Vol 64 (4) ◽  
pp. 1139-1142 ◽  
Author(s):  
Ilya Tsvankin, ◽  
Heloise B. Lynn,
Keyword(s):  
Special Section ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Special Issue ◽  
Azimuthal Dependence ◽  
Azimuthal Variation ◽  
Main Motivation ◽  
Development Scenarios ◽  
The Right ◽  
Lateral Heterogeneities

This special issue is based on papers presented at the post‐convention SEG workshop on azimuthal dependence of P-wave signatures held in Dallas in 1997. The main motivation for analyzing the azimuthal variation of seismic traveltimes, amplitudes, attenuation, etc. is to obtain reliable information about azimuthal anisotropy in the subsurface. Another potential application of multiazimuth techniques is in finding and mapping desirable lateral heterogeneities that could “masquerade” as azimuthal anisotropy. The last topic has not yet been fully discussed (and is not addressed in the special issue), but several exploration and development scenarios contain oriented lateral heterogeneities (sand channels, etc.) that at the right scale length could be highly visible in properly processed wide‐azimuth 3-D data.

Seismic critical-angle reflectometry: A method to characterize azimuthal anisotropy?

Geophysics ◽  
2007 ◽  
Vol 72 (3) ◽  
pp. D41-D50 ◽  
Author(s):  
Martin Landrø ◽  
Ilya Tsvankin
Keyword(s):  
Critical Angle ◽  
Transverse Isotropy ◽  
Symmetry Plane ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Head Wave ◽  
Orthorhombic Symmetry ◽  
Amplitude Curve ◽  
Diagnostic Features ◽  
Azimuthal Variation

Existing anisotropic parameter-estimation algorithms that operate with long-offset data are based on the inversion of either nonhyperbolic moveout or wide-angle amplitude-variation-with-offset (AVO) response. We show that valuable information about anisotropic reservoirs can also be obtained from the critical angle of reflected waves. To explain the behavior of the critical angle, we develop weak-anisotropy approximations for vertical transverse isotropy and then use Tsvankin’s notation to extend them to azimuthally anisotropic models of orthorhombic symmetry. The P-wave critical-angle reflection in orthorhombic media is particularly sensitive to the parameters [Formula: see text] and [Formula: see text] responsible for the symmetry-plane horizontal velocity in the high-velocity layer. The azimuthal variation of the critical angle for typical orthorhombic models can reach [Formula: see text], which translates into substantial changes in the critical offset of the reflected P-wave. The main diagnostic features of the critical-angle reflection employed in our method include the rapid amplitude increase at the critical angle and the subsequent separation of the head wave. Analysis of exact synthetic seismograms, generated with the reflectivity method, confirms that the azimuthal variation of the critical offset is detectable on wide-azimuth, long-spread data and can be qualitatively described by our linearized equations. Estimation of the critical offset from the amplitude curve of the reflected wave, however, is not straightforward. Additional complications may be caused by the overburden noise train and by the influence of errors in the overburden velocity model on the computation of the critical angle. Still, critical-angle reflectometry should help to constrain the dominant fracture directions and can be combined with other methods to reduce the uncertainty in the estimated anisotropy parameters.

Relationship of P-wave seismic attributes, azimuthal anisotropy, and commercial gas pay in 3-D P-wave multiazimuth data, Rulison Field, Piceance Basin, Colorado

Geophysics ◽  
1999 ◽  
Vol 64 (4) ◽  
pp. 1293-1311 ◽  
Author(s):  
Heloise B. Lynn ◽  
David Campagna ◽  
K. Michele Simon ◽  
Wallace E. Beckham
Keyword(s):  
Seismic Attributes ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Seismic Survey ◽  
Target Interval ◽  
Azimuthal Variation ◽  
Interval Velocity ◽  
Principal Axes ◽  
Naturally Fractured ◽  
Relationship Of

This case history is one of three field projects funded by the US Department of Energy as part of its ongoing research effort aimed to expand current levels of drilling and production efficiency in naturally‐fractured tight‐gas reservoirs. The original stated goal for the 3-D P-wave seismic survey was to evaluate and map fracture azimuth and relative fracture density throughout a naturally‐fractured gas reservoir interval. At Rulison field, this interval is the Cretaceous Mesaverde, approximately 2500 ft (760 m) of lenticular sands, silts, and shales. Three‐dimensional full‐azimuth P-wave data were acquired for the evaluation of azimuthal anisotropy and the relationship of the anisotropy to commercial pay in the target interval. The methodology is based on the evaluation of two restricted‐azimuth orthogonal (source‐receiver azimuth) 3-D P-wave volumes aligned with the natural principal axes of the azimuthal anisotropy, as estimated from velocity analysis of multiazimuth prestack gathers. The Dix interval velocity, as well as the interval amplitude variation with offset (AVO) gradient, was calculated for both azimuths for the gas‐saturated Mesaverde interval. The two seismic attributes best correlated with commercial gas pay (at a 21-well control set) were (1) values greater than 4% azimuthal variation in the interval velocity ratio (source‐receiver azimuth N60E/N30W) of the target interval (the gas‐saturated Mesaverde), and (2) the sum of the interval AVO gradients (N60E + N30W). The sum of the interval AVO gradients is an attribute sensitive to the presence of gas, but not diagnostic of an azimuthal variation in the amplitude. The two‐azimuth interval velocity anisotropy mapped over the survey area suggests spatial variations in the orientation of the maximum horizontal stress field and the open (to flow) fracture system.

scholarly journals Coughing as a potentially effective induction method of atrial tachycardia: a case report

2020 ◽  
Author(s):  
Reina Tonegawa-Kuji ◽  
Kenichiro Yamagata ◽  
Kengo Kusano
Keyword(s):  
Pulmonary Vein ◽  
Atrial Tachycardia ◽  
Superior Vena ◽  
Vena Cava ◽  
P Wave ◽  
Induction Method ◽  
Voluntary Cough ◽  
Wave Morphology ◽  
The Right

Abstract Background  Cough-induced atrial tachycardia (AT) is extremely rare and its electrical origin remains largely unknown. Atrial tachycardias triggered by pharyngeal stimulation, such as swallowing or speech, appears to be more common and the majority of them originate from the superior vena cava or right superior pulmonary vein (PV). Only one case of swallow-triggered AT with right inferior pulmonary vein (RIPV) origin has been reported to date. Case summary  We present a case of a 41-year-old man with recurring episodes of AT in the daytime. He underwent electrophysiology study without sedation. Atrial tachycardia was not observed when the patient entered the examination room and could not be induced with conventional induction procedures. By having the patient cough periodically on purpose, transient AT with P-wave morphology similar to the clinical AT was consistently induced. Activation mapping of the AT revealed a centrifugal pattern with the earliest activity localized inside the RIPV. After successful radiofrequency isolation of the right PV, AT was no longer inducible. Discussion  In the rare case of cough-induced AT originating from the RIPV, the proximity of the inferior right ganglionated plexi (GP) suggests the role of GP in triggering tachycardia. This is the first report that demonstrates voluntary cough was used to induce AT. In such cases that induction of AT is difficult using conventional methods, having the patient cough may be an effective induction method that is easy to attempt.

scholarly journals 2021 Special Issue on Software Tools and Resources: Finding the Right Tools for the Job

2021 ◽  
Vol 20 (4) ◽  
pp. 1819-1820
Author(s):  
Susan T. Weintraub ◽  
Michael R. Hoopmann ◽  
Magnus Palmblad
Keyword(s):  
Software Tools ◽  
Special Issue ◽  
The Right

scholarly journals Exploring Gender Differences in Support for Rightist Parties: The Role of Party and Gender Ideology

2018 ◽  
Vol 14 (01) ◽  
pp. 80-105 ◽  
Author(s):  
Rosie Campbell ◽  
Silvia Erzeel
Keyword(s):  
Gender Differences ◽  
Western Europe ◽  
Gender Ideology ◽  
Radical Right ◽  
Special Issue ◽  
Gender Ideologies ◽  
Populist Radical Right ◽  
And Gender ◽  
The Right

This contribution to the Special Issue on Gender and Conservatism uses expert and election surveys to explore the extent to which the feminist or traditional gender ideology of parties of the right relates to their economic and liberal/authoritarian ideology. We show that although parties of the left generally espouse more feminist ideologies than parties of the right, there are a significant number of rightist parties in Western Europe that combine laissez-faire economic values with liberal feminist ideals. That said, there is more homogeneity among parties of the populist radical right than rightist parties more generally. We find that despite some variation in their gender ideology, parties of the populist radical right overwhelmingly—with the exception of one party in the Netherlands—continue to adopt traditional or antifeminist gender ideologies. In terms of attracting women voters, we find that rightist parties who adopt a feminist gender ideology are able to attract more women voters than other parties of the right. We detect several examples of center-right parties that include feminist elements in their gender ideologies and are able to win over larger proportions of women voters than rightist parties that fail to adopt feminist positions.

scholarly journals Special Section on Rural and Remote ICT: Broadband Rural, Regional and National Impacts

2016 ◽  
Vol 20 ◽  
Author(s):  
Michael Steven Lane ◽  
Catherine Middleton ◽  
Ruediger Zarnekow ◽  
Khorshed Alam
Keyword(s):  
Special Section ◽  
Special Issue ◽  
Rural And Remote

Editorial for the Special Issue on Rural and Remote ICT: Broadband Rural, Regional and National Impacts

Anisotropic geometrical-spreading correction for wide-azimuth P-wave reflections

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. D161-D170 ◽  
Author(s):  
Xiaoxia Xu ◽  
Ilya Tsvankin
Keyword(s):  
Transversely Isotropic ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Fractured Reservoir ◽  
Geometrical Spreading ◽  
Spreading Factor ◽  
Velocity Anisotropy ◽  
Reflection Data ◽  
Fitting Procedure ◽  
Avo Attributes

Compensation for geometrical spreading along a raypath is one of the key steps in AVO (amplitude-variation-with-offset) analysis, in particular, for wide-azimuth surveys. Here, we propose an efficient methodology to correct long-spread, wide-azimuth reflection data for geometrical spreading in stratified azimuthally anisotropic media. The P-wave geometrical-spreading factor is expressed through the reflection traveltime described by a nonhyperbolic moveout equation that has the same form as in VTI (transversely isotropic with a vertical symmetry axis) media. The adapted VTI equation is parameterized by the normal-moveout (NMO) ellipse and the azimuthally varying anellipticity parameter [Formula: see text]. To estimate the moveout parameters, we apply a 3D nonhyperbolic semblance algorithm of Vasconcelos and Tsvankin that operates simultaneously with traces at all offsets andazimuths. The estimated moveout parameters are used as the input in our geometrical-spreading computation. Numerical tests for models composed of orthorhombic layers with strong, depth-varying velocity anisotropy confirm the high accuracy of our travetime-fitting procedure and, therefore, of the geometrical-spreading correction. Because our algorithm is based entirely on the kinematics of reflection arrivals, it can be incorporated readily into the processing flow of azimuthal AVO analysis. In combination with the nonhyperbolic moveout inversion, we apply our method to wide-azimuth P-wave data collected at the Weyburn field in Canada. The geometrical-spreading factor for the reflection from the top of the fractured reservoir is clearly influenced by azimuthal anisotropy in the overburden, which should cause distortions in the azimuthal AVO attributes. This case study confirms that the azimuthal variation of the geometrical-spreading factor often is comparable to or exceeds that of the reflection coefficient.

scholarly journals The Horizontal Effects of Charter Rights Given Expression to in EU Legislation, from Mangold to Bauer

2019 ◽  
Vol 12 (2) ◽  
pp. 185-215
Author(s):  
Elise Muir
Keyword(s):  
Case Law ◽  
Fundamental Rights ◽  
Special Issue ◽  
Max Planck ◽  
Eu Legislation ◽  
Scope Of Application ◽  
Effective Remedy ◽  
The Right ◽  
The Relationship ◽  
Eu Fundamental Rights

This paper investigates the relationship between legislative provisions and fundamental rights by analyzing the Egenberger, IR, Bauer, Max-Planck and Cresco cases. This paper understands these cases as an invitation to reflect on whether, and if so, to what extent, EU fundamental rights' legislation, read in conjunction with the Charter, could have an impact on the scope of application, substance and/or legal effects of the Charter. This paper argues that the Court of Justice's recent case law can be understood as allowing for EU legislative guidance on fundamental rights to interact in an upward process with the rights enshrined in norms with the same rank as EU primary law. This paper sheds light on the constitutional implications of the overlaps between legislation and constitutional norms on fundamental norms while other contributions in this special issue address effectiveness and the right to an effective remedy in a broader sense.

scholarly journals Prolonged Sinus Pauses upon Termination of Paroxysmal Atrial Fibrillation: Abnormal Right Atrial Electrophysiologic and Electroanatomic Findings

2017 ◽  
Vol 44 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Zhengyu Bao ◽  
Hongwu Chen ◽  
Bing Yang ◽  
Michael Shehata ◽  
Weizhu Ju ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Sinus Node ◽  
P Wave ◽  
Right Atrial ◽  
Control Group ◽  
Paroxysmal Supraventricular Tachycardia ◽  
Group A ◽  
Group B ◽  
Activation Times ◽  
The Right

The efficacy of pulmonary vein antral isolation for patients with prolonged sinus pauses (PSP) on termination of atrial fibrillation has been reported. We studied the right atrial (RA) electrophysiologic and electroanatomic characteristics in such patients. Forty patients underwent electroanatomic mapping of the RA: 13 had PSP (group A), 13 had no PSP (group B), and 14 had paroxysmal supraventricular tachycardia (control group C). Group A had longer P-wave durations in lead II than did groups B and C (115.5 ± 15.4 vs 99.5 ± 10.9 vs 96.5 ± 10.4 ms; P=0.001), and RA activation times (106.8 ± 13.8 vs 99 ± 8.7 vs 94.5 ± 9.1 s; P=0.02). Group A's PP intervals were longer during adenosine triphosphate testing before ablation (4.6 ± 2.3 vs 1.7 ± 0.6 vs 1.5 ± 1 s; P <0.001) and after ablation (4.7 ± 2.5 vs 2.2 ± 1.4 vs 1.6 ± 0.8 s; P <0.001), and group A had more complex electrograms (11.4% ± 5.4% vs 9.3% ± 1.6% vs 5.8% ± 1.6%; P <0.001). Compared with group C, group A had significantly longer corrected sinus node recovery times at a 400-ms pacing cycle length after ablation, larger RA volumes (100.1 ± 23.1 vs 83 ± 22.1 mL; P=0.04), and lower conduction velocities in the high posterior (0.87 ± 0.13 vs 1.02 ± 0.21 mm/ms; P=0.02) and high lateral RA (0.89 ± 0.2 vs 1.1 ± 0.35 mm/ms; P=0.04). We found that patients with PSP upon termination of atrial fibrillation have RA electrophysiologic and electroanatomic abnormalities that warrant post-ablation monitoring.

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