PROBLEM AREAS FOR THE SEISMOLOGIST

Geophysics ◽  
1953 ◽  
Vol 18 (4) ◽  
pp. 827-843
Author(s):  
Glenn M. Conklin
Keyword(s):  
Cross Sections ◽  
Salt Solution ◽  
Velocity Variation ◽  
Multiple Reflections ◽  
Hancock County ◽  
Texas Panhandle ◽  
Beaver County ◽  
Southern Florida

This paper describes interpretative problems encountered in four widely scattered areas: Southern Florida; Beaver County, Oklahoma; the Plainview Basin of the Texas Panhandle; and Hancock County, Mississippi. Secondary refraction recordings offer problems, because refractions from deep beds are distorted and obscured by energy from shallow beds. The energy associated with the shallow refractors appears as multiples and is sustained for long periods of time. In Beaver County, Oklahoma, extreme variations in velocity cause distortion of reflections and introduce apparent dips which are erroneous. This velocity variation is thought to be due to differential salt solution from the Blaine‐Cimarron interval. In the Plainview Basin of the Texas Panhandle and in Hancock County, Mississippi, multiple reflections are troublesome. These reflections are discussed and records and cross‐sections illustrate these events. Some suggestions for the treatment of these problems are advanced.

OIL AND GAS EXPLORATION IN ALABAMA, GEORGIA, AND FLORIDA

Geophysics ◽  
1953 ◽  
Vol 18 (2) ◽  
pp. 340-359 ◽  
Author(s):  
Robert B. Baum
Keyword(s):  
Cross Sections ◽  
Oil And Gas ◽  
Geophysical Methods ◽  
Oil Field ◽  
Oil Fields ◽  
Seismic Events ◽  
Oil And Gas Exploration ◽  
Contour Maps ◽  
Reflection Seismic ◽  
Southern Florida

The discovery of the Pollard oil field in southern Alabama early in 1952 sparked a campaign of leasing and exploration which spread quickly into Georgia and Florida. Three fields in southwestern Alabama and one in southern Florida account for all the oil production in the three states. Some aspects of the general geology and geophysics of the area, illustrated with maps, cross sections, and correlation charts, suggest the presence of geologic conditions favorable for the possible trapping and accumulation of oil and gas. Early seismograph exploration in much of the area was not effective, but in recent months the tempo of seismic activity has been accelerating, and improvements in instrumental and interpretive techniques are being achieved through current experimental work. The use of the various geophysical methods contributed to the discovery of the four oil fields located in the area. The structural traps indicated by the contour maps of the four fields are of the type sought by the reflection seismic method. Examples of representative reflection records indicate the presence of usable and correlatable seismic events. A seismic cross section prepared from data of this type shows the fault zone associated with the Pollard field. The existence of favorable geologic conditions in the southeastern states and the recent oil field successes at Pollard and South Carlton indicate the continuing of active development and exploration throughout the area.

scholarly journals DETERMINATION OF AN OPTIMAL PROCESSING FLOW FOR THE SUPPRESSION OF FREE-SURFACE MULTIPLES IN REAL 2D MARINE DATA

2013 ◽  
Vol 31 (1) ◽  
pp. 137
Author(s):  
Andrei Gomes de Oliveira ◽  
Ellen De Nazaré Souza Gomes
Keyword(s):  
Cross Sections ◽  
Multiple Reflections ◽  
Optimal Processing ◽  
Predictive Deconvolution ◽  
Air Water Interface ◽  
P Domain ◽  
Marine Data ◽  
Multiple Elimination ◽  
Processing Flow

The presence of multiple reflections is common in marine surveys due to the air-water interface. Multiples have significant energy and can mask deep reflectors, leading to the misinterpretation of seismic cross-sections. In this study, surface-related multiple elimination (SRME), predictive deconvolution in the domain τ − p domain and Radon and f − k filtering are used to eliminate surface multiples in real 2D marine data. These methods are applied in different combinations, and the results are analyzed with the aim of determining an optimal seismic processing flow for the removal of surface multiples. RESUMO: No levantamento marinho é comum a presença de reflexões múltiplas devido à interface ar-água. Essas reflexões múltiplas possuem energia considerável e podem mascarar reflexões primárias levando a erros de interpretação da seção sísmica. Neste trabalho é determinado um fluxo ótimo de processamento sísmico para atenuação de múltiplas de superfície. Os métodos de eliminação de múltiplas de superfície (SRME), deconvolução preditiva no domínio τ − p e as filtragens Radone f − k são aplicados a um dado marinho real 2D em diferentes combinações. Os resultados são analisados com objetivo de determinar um fluxo de processamento sísmico ótimo para atenuação de múltiplas de superfície.Palavras-chave: atenuação de múltiplas de superfície; SRME; filtragem Radon; deconvolução preditiva no domínio τ − p; filtragem f − k

Preliminary Evaluation of Electrical Resistance Tomography for Imaging Palm Trunks

2016 ◽  
Vol 42 (2) ◽  
Author(s):  
Monica Elliott ◽  
Timothy Broschat ◽  
Lothar Göcke
Keyword(s):  
Electrical Resistivity ◽  
Cross Sections ◽  
Electrical Resistance ◽  
Fungal Pathogens ◽  
Wood Decay ◽  
Preliminary Evaluation ◽  
Electrical Resistance Tomography ◽  
High Electrical Resistivity ◽  
Southern Florida ◽  
Syagrus Romanzoffiana

In a preliminary study, electrical resistance tomography (ERT) was used to obtain trunk images of Syagrus romanzoffiana, a common ornamental palm grown in southern Florida, U.S. Seven palms, four healthy and three diseased, were evaluated in the middle of the dry season, with four located in an irrigated site and three in a non-irrigated site. Two healthy and three diseased palms were felled and cross sections obtained to examine their internal structure and compare to the tomograms obtained. ERT was effective in illustrating the relative electrical resistance value of healthy palms, as the tomograms obtained for palms situated in the irrigated site (low electrical resistivity) were distinctly different from the tomograms of palms situated in the non-irrigated site (high electrical resistivity). ERT was also effective in visualizing internal palm trunk areas affected by the fungal pathogens Ganoderma zonatum, a wood decay pathogen, and Fusarium oxysporum f. sp. palmarum, a vascular wilt pathogen, as these areas had a low electrical resistivity.

MULTIPLE REFLECTIONS OF SEISMIC ENERGY

Geophysics ◽  
1948 ◽  
Vol 13 (1) ◽  
pp. 58-85 ◽  
Author(s):  
Raul F. Hansen ◽  
Curtis H. Johnson
Keyword(s):  
Cross Sections ◽  
Average Velocity ◽  
Quantitative Methods ◽  
Seismic Energy ◽  
Graphical Form ◽  
Multiple Reflections ◽  
The Earth ◽  
Straight Line ◽  
Considerable Work

This paper is a report of observations of multiple reflections in seismograph work in Argentina, of successful methods of identifying them, and of unsuccessful attempts to eliminate them. The paper begins with generalizations regarding the expectancy of multiples and develops geometrically (using straight‐line paths) the relation between multiples and their primary reflections for the cases of multiple reflection between a horizon and the surface and between two horizons, as regards time of reflection, dip and average velocity. The importance of a sharp reflecting contrast at the surface is emphasized, and it is concluded that the base of weathering may be more important in the formation of multiples than the surface of the earth. Early observations of multiple reflections from a volcanic flow and from a shallow basement are described. Other areas showed discordant data on the seismograms and cross sections, which, if due to multiples, could only be caused by multiple reflections from good sedimentary reflectors. In these areas a method for identifying both types of multiple reflections by their low average velocity as obtained by shooting reflection velocity‐profiles was developed, the work being facilitated by considerable knowledge of velocity and section from previous refraction shooting. Though this reflection velocity‐profile method is considered essential to positive and detailed identification of multiples, two methods of multiple identification using ΔT variations in continuous profiling are described and the results of considerable work with one of them are reported in graphical form, showing not only a separation of multiple from real reflections but also the determination of the true velocity‐depth function by means of the real reflections so segregated. Experiments are briefly described in which variations in size or depth of shot and variations in filters were not effective in reducing the ratio of multiple reflections to real reflections. The paper closes with suggestions for identifying multiple reflections by their abnormal curvatures in discontinuous, symmetrical‐spread dip shooting, and for using primitive qualitative methods where the topography or subsurface are not suited to the quantitative methods developed here.

MULTIPLE REFLECTION PROBLEMS IN WESTERN CANADA

Geophysics ◽  
1963 ◽  
Vol 28 (5) ◽  
pp. 882-893 ◽  
Author(s):  
Stanley A. Mouritsen
Keyword(s):  
Cross Sections ◽  
Multiple Reflection ◽  
The Other ◽  
Western Canada ◽  
Multiple Reflections ◽  
Oil Companies ◽  
Reef Structure ◽  
Seismic Records

The purpose of this paper is to stimulate interest in the problems of sedimentary multiple reflections in Canada and to show examples of some of the existing types. The types considered are: Second White Specks to the Paleozoic surface, the Blairmore to the Paleozoic surface, the suspected Ireton or base of the Nisku to the Paleozoic surface, the Devonian to the Paleozoic surface, and the base‐of‐weathering to the Paleozoic surface. Record examples were contributed by oil companies in Calgary to illustrate the Cretaceous‐to‐Paleozoic surface and the base‐of‐weathering‐to‐Paleozoic‐surface types. Records showing the other types are classified as confidential and unavailable. The base‐of‐weathering‐to‐Paleozoic‐surface multiple is shown with supporting cross‐sections and record‐sections as well as the simple field procedure, based on known data, that can be used by the field interpretation staff to help confirm this type of multiple. The problem of correctly interpreting seismic records where multiple reflections are present is discussed, and the criteria for distinguishing between multiple anomalies and true structures (particularly reef structure) presented. The conclusions drawn from the discussion are that for most types of multiple reflection interference accurate interpretations can be made. However, multiple reflections in certain areas can make definite interpretive results impossible.

scholarly journals Impact of round edge on the duct fluid flow: analytical investigation

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Mehran Khaki Jamei ◽  
Mohsen Heydari Alashti ◽  
Morteza Abbasi ◽  
Aliosat EbrahimNejad ◽  
Mohammad Hasan Taheri
Keyword(s):  
Velocity Profile ◽  
Cross Section ◽  
Cross Sections ◽  
Average Velocity ◽  
Constant Pressure ◽  
Circular Cross Section ◽  
Maximum Velocity ◽  
Analytical Investigation ◽  
Velocity Variation ◽  
Cylindrical Coordinates

AbstractThe present study aims to investigate the effect of the round edge on the laminar Newtonian fluid that flows through a channel. As an innovation, the sine and cosine transform functions are employed to solve the momentum governing equation in Cartesian and Cylindrical coordinates. Owing to the duct symmetric, only the quarter of the cross-section (θ = 0 to π/2) is analyzed. The analytical correlations for velocity distribution in both coordinates are provided; afterward, the effect of the round edge on the velocity profile has been investigated. It can be concluded that if a circular cross-section is replaced with a non-circular cross-section, the velocity profile becomes more uniform and less velocity variation is observed. Further, with a constant pressure gradient, among rectangular, round edge and circular cross-sections, the maximum velocity in a circular cross-section becomes minimum. In addition, it is observed that for the same pressure difference, an increase of m value leads to the higher average velocity and mass flow.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

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