Problems and interpretation of COCORP deep seismic reflection data, Wind River range, Wyoming

Geophysics ◽  
1981 ◽  
Vol 46 (12) ◽  
pp. 1684-1701 ◽  
Author(s):  
Ronald L. Zawislak ◽  
Scott B. Smithson
Keyword(s):  
Sedimentary Rocks ◽  
Problem Area ◽  
Multiple Reflections ◽  
Record Times ◽  
Seismic Reflection Data ◽  
Velocity Inversion ◽  
Wind River Range ◽  
Reflection Data ◽  
Structural Style ◽  
Crustal Reflection

Before the Consortium for Continental Reflection Profiling (COCORP) deep crustal reflection profile across the Wind River range, Wyoming, can be understood, problems involving velocity, multiple reflections, and structural style associated with thrusting must be resolved. Measurements from boreholes to maximum depths of 7.8 km show that a strong velocity inversion is associated with overpressured zones, primarily in Cretaceous shales. One‐dimensional (1-D) synthetic seismograms generated using the detailed velocity distribution closely duplicate the seismic trace on line 1 and produce multiple reflections of significant amplitude to record times of l0 sec. Other data including auto‐correlograms demonstrate presence of abundant multiple reflection energy to times of 10 to 12 sec on lines 1 and 2 and suggest that most of the deep events on these lines are multiple reflections. Because this area has not been known as a problem area for multiples in shallow (industry) reflection surveys, we conclude that multiples are a greater impediment for deep crustal reflection studies than has previously been recognized and that the sedimentary section must be treated much like the weathered zone in shallow seismic studies. Two‐dimensional (2-D) modeling and hand migration are used to determine structure in sedimentary rocks beneath the thrust Precambrian wedge. They suggest that structural as well as velocity uplift is found under the thrust, that a wedge of overturned sedimentary rocks parallels the thrust, and that the deeper sedimentary rocks bend down into the thrust.

Migration with reduced artifacts from internal multiple reflections

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. A25-A29
Author(s):  
Lele Zhang
Keyword(s):  
Seismic Reflection ◽  
Computational Cost ◽  
Data Sets ◽  
Square Root ◽  
Multiple Reflections ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Recent Developments ◽  
Multiple Elimination

Migration of seismic reflection data leads to artifacts due to the presence of internal multiple reflections. Recent developments have shown that these artifacts can be avoided using Marchenko redatuming or Marchenko multiple elimination. These are powerful concepts, but their implementation comes at a considerable computational cost. We have derived a scheme to image the subsurface of the medium with significantly reduced computational cost and artifacts. This scheme is based on the projected Marchenko equations. The measured reflection response is required as input, and a data set with primary reflections and nonphysical primary reflections is created. Original and retrieved data sets are migrated, and the migration images are multiplied with each other, after which the square root is taken to give the artifact-reduced image. We showed the underlying theory and introduced the effectiveness of this scheme with a 2D numerical example.

SEISMIC VELOCITIES FROM SURFACE MEASUREMENTS

Geophysics ◽  
1955 ◽  
Vol 20 (1) ◽  
pp. 68-86 ◽  
Author(s):  
C. Hewitt Dix
Keyword(s):  
Accurate Determination ◽  
Careful Study ◽  
Seismic Velocities ◽  
Multiple Reflections ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Surface Measurements ◽  
Secondary Objective ◽  
Interval Velocities

The purpose of this paper is to discuss field and interpretive techniques which permit, in favorable cases, the quite accurate determination of seismic interval velocities prior to drilling. A simple but accurate formula is developed for the quick calculation of interval velocities from “average velocities” determined by the known [Formula: see text] technique. To secure accuracy a careful study of multiple reflections is necessary and this is discussed. Although the principal objective in determining velocities is to allow an accurate structural interpretation to be made from seismic reflection data, an important secondary objective is to get some lithological information. This is obtained through a correlation of velocities with rock type and depth.

Labeling long‐period multiple reflections

Geophysics ◽  
1989 ◽  
Vol 54 (1) ◽  
pp. 122-126 ◽  
Author(s):  
R. J. J. Hardy ◽  
M. R. Warner ◽  
R. W. Hobbs
Keyword(s):  
Seismic Reflection ◽  
High Amplitude ◽  
Data Sets ◽  
Multiple Reflections ◽  
Multiple Series ◽  
Seismic Reflection Data ◽  
Long Period ◽  
Reflection Data ◽  
Zero Offset ◽  
Marine Seismic

The many techniques that have been developed to remove multiple reflections from seismic data all leave remnant energy which can cause ambiguity in interpretation. The removal methods are mostly based on periodicity (e.g., Sinton et al., 1978) or the moveout difference between primary and multiple events (e.g., Schneider et al., 1965). They work on synthetic and selected field data sets but are rather unsatisfactory when applied to high‐amplitude, long‐period multiples in marine seismic reflection data acquired in moderately deep (700 m to 3 km) water. Differential moveout is often better than periodicity at discriminating between types of events because, while a multiple series may look periodic to the eye, it is only exactly so on zero‐offset reflections from horizontal layers. The technique of seismic event labeling described below works by returning offset information from CDP gathers to a stacked section by color coding, thereby discriminating between seismic reflection events by differential normal moveout. Events appear as a superposition of colors; the direction of color fringes indicates whether an event has been overcorrected or undercorrected for its hyperbolic normal moveout.

scholarly journals Target-enclosed seismic imaging

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. Q53-Q66 ◽  
Author(s):  
Joost van der Neut ◽  
Matteo Ravasi ◽  
Yi Liu ◽  
Ivan Vasconcelos
Keyword(s):  
Seismic Reflection ◽  
Target Volume ◽  
Multiple Reflections ◽  
Reflection And Transmission ◽  
Seismic Reflection Data ◽  
Computational Burden ◽  
Reflection Data ◽  
Seismic Resolution ◽  
Marchenko Equation ◽  
Deconvolution Problem

Seismic reflection data can be redatumed to a specified boundary in the subsurface by solving an inverse (or multidimensional deconvolution) problem. The redatumed data can be interpreted as an extended image of the subsurface at the redatuming boundary, depending on the subsurface offset and time. We retrieve target-enclosed extended images by using two redatuming boundaries, which are selected above and below a specified target volume. As input, we require the upgoing and downgoing wavefields at both redatuming boundaries due to impulsive sources at the earth’s surface. These wavefields can be obtained from actual measurements in the subsurface, they can be numerically modeled, or they can be retrieved by solving a multidimensional Marchenko equation. As output, we retrieved virtual reflection and transmission responses as if sources and receivers were located at the two target-enclosing boundaries. These data contain all orders of reflections inside the target volume but exclude all interactions with the part of the medium outside this volume. The retrieved reflection responses can be used to image the target volume from above or from below. We found that the images from above and below are similar (given that the Marchenko equation is used for wavefield retrieval). If a model with sharp boundaries in the target volume is available, the redatumed data can also be used for two-sided imaging, where the retrieved reflection and transmission responses are exploited. Because multiple reflections are used by this strategy, seismic resolution can be improved significantly. Because target-enclosed extended images are independent on the part of the medium outside the target volume, our methodology is also beneficial to reduce the computational burden of localized inversion, which can now be applied inside the target volume only, without suffering from interactions with other parts of the medium.

EXPLORATION HORIZONS FROM NEW SEISMIC CONCEPTS OF CDP AND DIGITAL PROCESSING

Geophysics ◽  
1967 ◽  
Vol 32 (2) ◽  
pp. 207-224 ◽  
Author(s):  
John D. Marr ◽  
Edward F. Zagst
Keyword(s):  
Data Processing ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Synthetic Data ◽  
Digital Processing ◽  
Seismic Data Processing ◽  
Multiple Reflections ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Recent Developments

The more recent developments in common‐depth‐point techniques to attenuate multiple reflections have resulted in an exploration capability comparable to the development of the seismic reflection method. The combination of new concepts in digital seismic data processing with CDP techniques is creating unforeseen exploration horizons with vastly improved seismic data. Major improvements in multiple reflection and reverberation attenuation are now attainable with appropriate CDP geometry and special CDP stacking procedures. Further major improvements are clearly evident in the very near future with the use of multichannel digital filtering‐stacking techniques and the application of deconvolution as the first step in seismic data processing. CDP techniques are briefly reviewed and evaluated with real and experimental data. Synthetic data are used to illustrate that all seismic reflection data should be deconvolved as the first processing step.

Inversion of the Proterozoic Wernecke basin during tectonic development of the Racklan Orogen, northwest Canada

1994 ◽  
Vol 31 (3) ◽  
pp. 447-457 ◽  
Author(s):  
Marlene Dredge Mitchelmore ◽  
Frederick A. Cook
Keyword(s):  
Seismic Reflection ◽  
Sedimentary Rocks ◽  
Drill Hole ◽  
Seismic Reflection Data ◽  
Potential Field Data ◽  
Eastern Front ◽  
Reflection Data ◽  
Tectonic Development ◽  
Mackenzie Mountains ◽  
Middle Proterozoic

New deep seismic reflection data coupled with regional stratigraphic correlations, drill-hole information, and potential field data are interpreted to provide images of Middle Proterozoic Wernecke Supergroup (meta-)sedimentary layers that were uplifted during tectonic development of the ca. 0.9–1.3 Ga Racklan Orogen in Canada's western Northwest Territories. The reflection data are located at the eastern front of the Mackenzie Mountains portion of the Canadian Cordillera and on the western flank of the Fort Simpson structural trend that is a prominent Proterozoic structure in the subsurface throughout the region. Along three parallel profiles, layers that are correlated with thick Wernecke Supergroup sedimentary rocks produce prominent reflections between about 3.0 and 9.0 s (about 7.5 and 23 km) that were arched prior to deposition of younger Proterozoic (probably Mackenzie Mountains Supergroup) and Phanerozoic sedimentary rocks. The strata are considered to be Wernecke basin sedimentary rocks that were uplifted during deformation associated with the development of the Racklan Orogen.

Deformation styles at the Appalachian structural front, western Newfoundland: implications of new industry seismic reflection data

1998 ◽  
Vol 35 (11) ◽  
pp. 1288-1306 ◽  
Author(s):  
Glen S Stockmal ◽  
Art Slingsby ◽  
John WF Waldron
Keyword(s):  
Seismic Reflection ◽  
Hydrocarbon Exploration ◽  
Canadian Cordillera ◽  
Seismic Reflection Data ◽  
Middle Ordovician ◽  
Reflection Data ◽  
Triangle Zone ◽  
Structural Style ◽  
Southeastern Margin ◽  
New Industry

New seismic reflection data gathered during hydrocarbon exploration in and adjacent to the external Humber zone, western Newfoundland, have important implications for the interpretation of structural style at the Appalachian front. These new data indicate that the structural front is influenced by both thin-skinned and thick-skinned structures. Where the structural front is thin skinned, it is characterized by a triangle zone, or tectonic wedge, similar to structures observed at the southeastern margin of the Canadian Cordillera, and at other orogenic fronts. The thin-skinned tectonic wedge is overridden locally by thick-skinned thrusts, which are generally emergent but are locally blind, forming a thick-skinned tectonic wedge. Timing relationships indicate that, although initial motion occurred during the Early to Middle Ordovician Taconian orogeny, the thin-skinned allochthonous slices in western Newfoundland were not emplaced until Devonian time (the Acadian orogeny). Thick-skinned deformation, which postdates thin-skinned thrusting, probably occurred between Middle Devonian and earliest Carboniferous time.

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