Flexural Wave Dispersion Analysis for Reservoir Characterization with a Small Diameter Cross Dipole Tool

2011 ◽  
Author(s):  
David Eccles ◽  
Terry Mayor ◽  
Yibing Zheng ◽  
Peter A.S. Elkington
Keyword(s):  
Reservoir Characterization ◽  
Small Diameter ◽  
Wave Dispersion ◽  
Dispersion Analysis ◽  
Flexural Wave

scholarly journals Study of Abnormal Group Velocities in Flexural Metamaterials

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hong Woo Park ◽  
Joo Hwan Oh
Keyword(s):  
Group Velocity ◽  
Periodic Structure ◽  
Three Dimensional ◽  
Wave Dispersion ◽  
Abnormal Behavior ◽  
Flexural Wave ◽  
Negative Group ◽  
One Dimensional ◽  
Optical Branch ◽  
Negative Group Velocity

Abstract Generally, it has been known that the optical branch of a simple one-dimensional periodic structure has a negative group velocity at the first Brillouin zone due to the band-folding effect. However, the optical branch of the flexural wave in one-dimensional periodic structure doesn’t always have negative group velocity. The problem is that the condition whether the group velocity of the flexural optical branch is negative, positive or positive-negative has not been studied yet. In consequence, who try to achieve negative group velocity has suffered from trial-error process without an analytic guideline. In this paper, the analytic investigation for this abnormal behavior is carried out. In particular, we discovered that the group velocity of the optical branch in flexural metamaterials is determined by a simple condition expressed in terms of a stiffness ratio and inertia ratio of the metamaterial. To derive the analytic condition, an extended mass-spring system is used to calculate the wave dispersion relationship in flexural metamaterials. For the validation, various numerical simulations are carried out, including a dispersion curve calculation and three-dimensional wave simulation. The results studied in this paper are expected to provide new guidelines in designing flexural metamaterials to have desired wave dispersion curves.

A History of Nuclear Spectroscopy in Well Logging

2020 ◽  
Vol 61 (6) ◽  
pp. 523-548
Author(s):  
Richard Pemper ◽  
Keyword(s):  
Reservoir Characterization ◽  
Gamma Ray ◽  
Technological Development ◽  
Small Diameter ◽  
Well Logging ◽  
Nuclear Spectroscopy ◽  
History Of ◽  
The Rich ◽  
Natural Gas Reservoirs ◽  
Pulsed Neutron

This paper provides a history of nuclear spectroscopy in well logging from its beginnings in 1939 up until the present day. After the invention and implementation of gamma ray logging, this paper traces the technological development of the pulsed-neutron capture (sigma) log, the spectral gamma ray log, the carbon-oxygen log, tracer identification logs, small-diameter reservoir characterization tools, and finally the geochemical log. The key to the science of nuclear spectroscopy has been the detection of gamma rays, their energies, and the identity of their parent atomic nuclei. From this, the properties of the formation can be better understood. There have been many advances in technology that have led to the current state of nuclear spectroscopy tools. The most notable has been the ability to detect the presence of a gamma ray. After this came numerous advances in scintillator crystal detector technology, the pulsed-neutron generator, the energy digitization of gamma ray pulses, fast-timing electronics, and powerful computers. These advances have made possible the complex, gamma ray-centric logging tools that we have today that have helped petroleum engineers in the energy industry locate and produce hydrocarbon, kerogen, and natural gas reservoirs for the benefit of each individual in the world. This paper discusses the rich history of these historic developments.

An Error Indicator Based on a Wave Dispersion Analysis for the Vibration Modes of Isotropic Elastic Solids Discretized by Energy-Orthogonal Finite Elements

2019 ◽  
Author(s):  
Francisco José Brito
Keyword(s):  
Finite Element ◽  
Elastic Energy ◽  
Wave Dispersion ◽  
Dispersion Analysis ◽  
Higher Order ◽  
Elastic Solids ◽  
Error Indicator ◽  
Energy Error ◽  
Isotropic Media ◽  
Order Components

This paper studies the dispersion of elastic waves in isotropic media discretized by the finite element method. The element stiffness matrix is split into basic and higher order components which are respectively related to the mean and deviatoric components of the element strain field. This decomposition is applied to the elastic energy of the finite element assemblage. By a dispersion analysis the higher order elastic energy is related to the elastic energy error for the propagating waves. An averaged correlation is proposed and successfully tested as an error indicator for finite element vibration eigenmodes.

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