Browsing Earth Resources Laboratory by Title
Now showing items 301-320 of 456
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Nonlinear Semblance Processing For The Evaluation Of An Acoustic Altered Zone Around The Borehole
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)This paper describes a simple method to evaluate an acoustic altered zone around the borehole using an array of sonic waveforms. The method is based on a semblance velocity analysis and a nonlinear travel time window is ... -
Nonlinear Soil Response in the Near-Field of a Vibrator Truck: Application to Land Seismic Surveys
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2007)The nonlinear behavior of soils can significantly modify the wavelet radiated from vibrator trucks. In this paper, we describe a field experiment designed to measure the nonlinear response of a natural soil formation in ... -
A Novel Application of Time Reversed Acoustics: Salt Dome Flank Imaging Using Walk Away VSP Surveys
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2005)In the past few years, there has been considerable research and interest in a topic known by various names, such as Time Reverse Acoustics (TRA), Time Reverse Mirrors (TRM), and Time Reverse Cavities (TRC), which exploits ... -
A Novel Application of Time Reversed Acoustics: Salt Dome Flank Imaging Using Walkaway VSP surveys
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2006-03-01)In this paper we present initial results of applying Time-Reversed Acoustics (TRA) technology to saltdome flank, seismic imaging. We created a set of synthetic traces representing a multilevel, walkaway VSP for a model ... -
Nullerical Studies of Body Wave Amplitudes in Full Waveform Acoustic Logs
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)The amplitudes of P and S head waves in a full waveform acoustic log microseismogram are studied numerically as a function of borehole and formation parameters. The technique used is contour integration around the respective ... -
A Numerical Investigation of Head Waves and Leaky Modes in Fluid-Filled Boreholes
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1985)Although synthetic borehole seismograms routinely can be computed for a wide range of borehole conditions, the physical nature of shear and compressional head waves in fluid-filled boreholes is poorly understood. This ... -
Numerical modeling of elastic wave scattering by near-surface heterogeneities
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2013)A perturbation method for elastic waves and numerical forward modeling are used to calculate the effects of seismic wave scattering from arbitrary shape shallow subsurface heterogeneities. Wave propagation is simulated ... -
Numerical Modeling of Seismic Wave Propagation at the Micro-Scale in Digitized Sandstone
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2007)In this paper, we first examine the relationship between the relative particle motions of fluids and solids and the seismic signal received when compressional waves propagate through saturated porous materials. We use a ... -
Numerical Modeling of Transport Properties and Comparison to Laboratory Measurements
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2008-06-10)Transport properties, such as permeability and electrical conductivity, are important in many geophysical and petroleum applications. The microstructure of a porous medium and physical characteristics of the solid and ... -
Numerical Simulation Of The Acoustic And Elastic Wavefields Radiated By A Source In A Fluid-Filled Borehole Embedded In A Layered Medium
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)We present a method of calculation to simulate the propagation of acoustic and elastic waves generated by a borehole source embedded in a layered medium. The method is formulated as a boundary element technique where the ... -
Numerical simulation of wave-induced fluid flow in digitized porous media using a coupled model with Level Set
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2008)In this paper, we develop a unified mathematical model with velocity as the primary variable for modeling the interaction between incompressible fluid and compressible solid. We numerically solve this problem ... -
A Numerical Study of the Effects of Wave-Induced Fluid Flow in Porous Media: Linear Solver
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2009)In this paper, we present a computational method to simulate wave propagation in porous rocks saturated with Newtonian fluids over a range of frequencies of interest. The method can use a digital representation of a rock ... -
An Object-Oriented System for Full Waveform Data Processing
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1987)A new approach to the processing of sequences of full waveform acoustic logs is investigated. The rationale for this approach is primarily based on the observation that processing and interpretation tasks strongly depend ... -
Off-Center Monopole And Dipole Sources In Fluid-Filled Boreholes
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1996)A variety of seismic testing techniques rely on the use of seismic sources, detectors, or both, placed at some depth below the ground surface; these are often installed within fluid-filled boreholes. The interpretation ... -
One-Way Wave Propagators For Velocity Analysis On Curvilinear Coordinates
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2008)Due to present computational limitations, migration by the one-way wave equation remains an integral tool in seismic exploration. For the realistic interpretation of common image point gathers, it is necessary that migration ... -
Optimal Absorbing Boundary Conditions For Finite Difference Modeling Of Acoustic And Elastic Wave Propagation
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1993)An optimal absorbing boundary condition is designed to model acoustic and elastic wave propagation in 2D and 3D media using the finite difference method. In our method, extrapolation on the artificial boundaries of a ... -
Optimal Experiment Design for Timelapse Tomography: Customizing Crosswell Micro-Arrays for Monitoring Applications
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2007-05-07)Geophysical monitoring techniques offer the only approach capable of assessing both the spatial and temporal dynamics of subsurface fluid processes. Historically, monitoring datasets have consisted of surveys sequentially ... -
Orientation Estimation for Multiple Large Fractures by Scattering Energy
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2006)We have done the numerical modeling of seismic response to multiple sets of vertical large fractures by using finite-difference method (FD), which can easily handle media with monoclinic anisotropy. We consider three types ... -
P And S Wave Velocity Determination
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)There are three general methods that can be used to determine formation velocities from full waveform logs. The first approach is to make use of the data from the entire waveform. This type of velocity analysis is performed ... -
P and SV waves 3-D Numerical Modeling of AVOA from Heterogeneous Fractured Reservoirs
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1997)We study the effects of fracture-induced anisotropy and lateral fracture density heterogeneity on the reflected P and SV wave amplitude variation with offset and azimuth (AVOA), using 3-D finite-difference simulations. The ...
