APPARENT ATTENUATION DUE TO INTRABED MULTIPLES, II

Geophysics ◽  
1978 ◽  
Vol 43 (4) ◽  
pp. 730-737 ◽  
Author(s):  
M. Schoenberger ◽  
F. K. Levin
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Seismic Waves ◽  
Synthetic Seismograms ◽  
Frequency Dependent ◽  
Total Attenuation ◽  
The World ◽  
Apparent Attenuation

In a paper with the same title published in Geophysics (June 1974), we showed that synthetic seismograms from two wells gave a frequency‐dependent attenuation due to intrabed multiples of about 0.06 dB/wavelength. This loss was 1/3 to 1/2 of the total attenuation found for field data on lines near the wells. Our data sufficed to confirm the conclusion of O’Doherty and Anstey that attenuation caused by intrabed multiples may be appreciable, but the number of wells was insufficient to establish the magnitude of that attenuation in general. To get a better feel for intrabed multiple‐generated attenuation, we have computed losses for 31 additional wells from basins all over the world. Sonic and, where available, density logs were digitized every foot and converted into synthetic seismograms with 50 orders of intrabed multiples. Using the technique of the 1974 paper of extending the logs and placing an isolated reflector 2000 ft below the bottom of the wells, we computed attenuation constants for plane seismic waves that had traveled down and back through the subsurfaces defined by the logs. Computed constants varied from 0.01 dB/wavelength to 0.22 dB/wavelength. Total traveltimes ranged from 0.7 to 2.7 sec; the average was 1.9 sec. Attenuation constants computed from surface seismic data near four of the 31 wells gave values 1.3 to 7 times the corresponding intrabed constants. Thus, attenuation due to intrabed multiples accounts for an appreciable fraction of the observed attenuation but by no means all of it.

scholarly journals High-resolution coherency functionals for velocity analysis: An application for subbasalt seismic exploration

Geophysics ◽  
2013 ◽  
Vol 78 (5) ◽  
pp. U53-U63 ◽  
Author(s):  
Andrea Tognarelli ◽  
Eusebio Stucchi ◽  
Alessia Ravasio ◽  
Alfredo Mazzotti
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Field Data ◽  
Signal To Noise Ratio ◽  
Synthetic Seismograms ◽  
Seismic Exploration ◽  
Velocity Analysis ◽  
Signal To Noise ◽  
Geologic Setting ◽  
Analytic Signals

We tested the properties of three different coherency functionals for the velocity analysis of seismic data relative to subbasalt exploration. We evaluated the performance of the standard semblance algorithm and two high-resolution coherency functionals based on the use of analytic signals and of the covariance estimation along hyperbolic traveltime trajectories. Approximate knowledge of the wavelet was exploited to design appropriate filters that matched the primary reflections, thereby further improving the ability of the functionals to highlight the events of interest. The tests were carried out on two synthetic seismograms computed on models reproducing the geologic setting of basaltic intrusions and on common midpoint gathers from a 3D survey. Synthetic and field data had a very low signal-to-noise ratio, strong multiple contamination, and weak primary subbasalt signals. The results revealed that high-resolution coherency functionals were more suitable than semblance algorithms to detect primary signals and to distinguish them from multiples and other interfering events. This early discrimination between primaries and multiples could help to target specific signal enhancement and demultiple operations.

An investigation into the fundamental relationships between attenuation, phase dispersion, and frequency using seismic refraction profiles over sedimentary structures

Geophysics ◽  
1987 ◽  
Vol 52 (1) ◽  
pp. 72-87 ◽  
Author(s):  
R. S. Jacobson
Keyword(s):  
Frequency Dependence ◽  
Seismic Waves ◽  
Velocity Dispersion ◽  
Seismic Refraction ◽  
Systematic Investigation ◽  
Data Sets ◽  
Frequency Dependent ◽  
Frequency Independent ◽  
Apparent Attenuation ◽  
Seismic Refraction Data

Despite many attenuation measurements which indicate a linear functional frequency dependence of absorption or constant [Formula: see text] in sediments, several theories predict no such linear dependence. The primary justification for rejecting a first‐power frequency dependence of attenuation is that it implies that seismic waves cannot propagate causally. Seismic waves must also travel with some velocity dispersion to satisfy causality, yet there is a lack of velocity dispersion measurements in sediments. In‐situ attenuation is caused by two distinct mechanisms: anelastic heating, and scattering due to interbed multiples. Apparent, or scattering, attenuation can produce both frequency‐dependent and non‐frequency‐dependent effects. Accurate measurements of attenuation and velocity dispersion are difficult; it is not surprising that a systematic investigation into the frequency dependence of absorption and velocity has not been made. A reinvestigation into two seismic refraction data sets collected over thickly stratified deep‐sea fans indicates that [Formula: see text] should not be assumed to be independent of frequency. Further, significant frequency‐independent absorption is present, indicating a high degree of apparent attenuation. Phase, or velocity, dispersion was also measured, but the results are more ambiguous than those for attenuation, due to inherent limitations of digital signals. Nevertheless, the absorption and velocity dispersion results are largely compatible, suggesting that if apparent attenuation is observed, then the scattered waves propagate causally.

Diffraction of seismic waves by cracks with application to hydraulic fracturing

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 253-265 ◽  
Author(s):  
Enru Liu ◽  
Stuart Crampin ◽  
John A. Hudson
Keyword(s):  
Hydraulic Fracturing ◽  
Born Approximation ◽  
Field Data ◽  
Seismic Waves ◽  
Crack Size ◽  
Synthetic Seismograms ◽  
Kirchhoff Approximation ◽  
Function Representation ◽  
Fracture Length ◽  
Diffracted Waves

We describe a method of modeling seismic waves interacting with single liquid‐filled large cracks based on the Kirchhoff approximation and then apply it to field data in an attempt to estimate the size of a hydraulic fracture. We first present the theory of diffraction of seismic waves by fractures using a Green's function representation and then compute the scattered radiation patterns and synthetic seismograms for fractures with elliptical and rectangular shapes of various dimensions. It is shown that the characteristics of the diffracted wavefield from single cracks are sensitive to both crack size and crack shape. Finally, we compare synthetic waveforms to observed waveforms recorded during a hydraulic fracturing experiment and are able to predict successfully the size of a hydraulically induced fracture (length and height). In contrast to previously published work based on the Born approximation, we model both phases and amplitudes of observed diffracted waves. Our modeling has resulted in an estimation of a crack length 1.1 to 1.5 times larger than previously predicted, whereas the height remains essentially the same as that derived using other techniques. This example demonstrates that it is possible to estimate fracture dimensions by analyzing diffracted waves.

Nonlinear pairwise alignment of seismic traces

Geophysics ◽  
2004 ◽  
Vol 69 (6) ◽  
pp. 1552-1559 ◽  
Author(s):  
Christopher L. Liner ◽  
Robert G. Clapp
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Pairwise Alignment ◽  
Optimization Method ◽  
Synthetic Seismograms ◽  
Amino Acid Sequences ◽  
Global Alignment ◽  
Global Optimization Method ◽  
S Wave ◽  
Alignment Problem

Seismic trace alignment is a recurring need in seismic processing and interpretation. For global alignment via static shift, there are robust tools available, including crosscorrelation. However, another kind of alignment problem arises in applications as diverse as associating synthetic seismograms to field data, harmonizing P‐ and S‐wave data, residual NMO, and final multilevel flattening of common image gathers. These cases require combinations of trace compression, extension, and shift—all of which are time variant. The difficulty is to find a mapping between the traces that is in some senseoptimum. This problem is solved here using a modified form of the Needleman‐Wunsch algorithm, a global optimization method originally developed for aligning amino acid sequences in proteins. Applied to seismic traces, this algorithm provides a nonlinear mapping of one seismic trace onto another. The method extends to multitrace alignment since that problem can be broken down into a cascade of pairwise alignments. Seismic implementation of the Needleman‐Wunsch algorithm is a promising new tool for nonlinear alignment and flattening of seismic data.

scholarly journals Application of Frequency-Dependent Traveltime Tomography to 2D Crosswell Seismic Field Data

2017 ◽  
Vol 22 (4) ◽  
pp. 421-426 ◽  
Author(s):  
Jianping Liao ◽  
Zhenwei Guo ◽  
Hexiu Liu ◽  
Shixin Dai ◽  
Yanlin Zhao ◽  
...  
Keyword(s):  
High Resolution ◽  
Field Data ◽  
Seismic Waves ◽  
Velocity Model ◽  
Oil Field ◽  
Frequency Dependent ◽  
Traveltime Tomography ◽  
First Arrival ◽  
Forward And Inverse Modeling ◽  
High Resolution Reconstruction

We applied Zelt's new frequency-dependent traveltime tomography (FDTT) method to 2D crosswell seismic field data from an eastern oil field in China. The FDTT uses the frequency content in the seismic waves in both the forward and inverse modeling steps. Although FDTT only uses a 300 Hz frequency to invert the dataset, the degree of matching between the inverted layers from FDTT and that of a sonic well logging curve is high, which shows that FDTT provides a high resolution reconstruction of subsurface structure through the simple use of the first-arrival traveltime data. The case study demonstrates that the FDTT algorithm is practical and can stand up to the complexities of a real 2D crosswell dataset. Additionally, we show that the FDTT method can create a high resolution long wavelength velocity model.

Network analysis models – the secret for success

2004 ◽  
Vol 4 (5-6) ◽  
pp. 383-388
Author(s):  
D.M. Rogers
Keyword(s):  
Mathematical Model ◽  
Field Data ◽  
Essential Element ◽  
Distribution Networks ◽  
Automatic Calibration ◽  
Supply And Distribution ◽  
The World ◽  
Optimum Approach ◽  
Analysis Models

Water is a fundamental necessity of life. Yet water supply and distribution networks the world over are old and lacking in adequate maintenance. Consequently they often leak as much water as they deliver and provide an unacceptable quality of service to the customer. In certain parts of the world, water is available only for a few hours of the day. The solution is to build a mathematical model to simulate the operation of the real network in all of its key elements and apply it to optimise its operation. To be of value, the results of the model must be compared with field data. This process is known as calibration and is an essential element in the construction of an accurate model. This paper outlines the optimum approach to building and calibrating a mathematical model and how it can be applied to automatic calibration systems.

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.

Topographic corrections to slowness measurements in parsimonious migration of land data

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. S77-S80 ◽  
Author(s):  
Ibrahim Z. Basi ◽  
George A. McMechan
Keyword(s):  
Seismic Data ◽  
Field Data

Parsimonious migration requires that incident and emergent angles be measured, via apparent slownesses, from the seismic data being migrated. When slownesses are measured from land data, it is the apparent slowness along the topography, not the horizontal slowness that is being measured. Thus, errors are introduced into the incident and emergent angle estimates, which are defined via horizontal slownesses. These errors can be corrected using the local topographic dips. A 2D field data example shows that, after correction, a migrated image has significantly improved coherency.

Laplace-domain full-waveform inversion of seismic data lacking low-frequency information

Geophysics ◽  
2012 ◽  
Vol 77 (5) ◽  
pp. R199-R206 ◽  
Author(s):  
Wansoo Ha ◽  
Changsoo Shin
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Single Frequency ◽  
Frequency Content ◽  
Laplace Domain ◽  
Frequency Information ◽  
Velocity Models ◽  
Gaussian Source

The lack of the low-frequency information in field data prohibits the time- or frequency-domain waveform inversions from recovering large-scale background velocity models. On the other hand, Laplace-domain waveform inversion is less sensitive to the lack of the low frequencies than conventional inversions. In theory, frequency filtering of the seismic signal in the time domain is equivalent to a constant multiplication of the wavefield in the Laplace domain. Because the constant can be retrieved using the source estimation process, the frequency content of the seismic data does not affect the gradient direction of the Laplace-domain waveform inversion. We obtained inversion results of the frequency-filtered field data acquired in the Gulf of Mexico and two synthetic data sets obtained using a first-derivative Gaussian source wavelet and a single-frequency causal sine function. They demonstrated that Laplace-domain inversion yielded consistent results regardless of the frequency content within the seismic data.

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