Browsing ERL Industry Consortia Technical Reports by Title
Now showing items 293-312 of 456
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Near-Surface Scattering From High Velocity Carbonates In West Texas
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1998)Seismic data acquired directly over near-surface limestone formations are commonly observed to be of inferior quality. A possible cause for this degradation is scattering in the near-subsurface by, e.g., the weathering ... -
New Applications In The Inversion Of Acoustic Full Waveform Logs - Relating Mode Excitation To Lithology
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1986-01-01)Existing techniques for the quantitative interpretation of waveform data have been based on one of two fundamental approaches: 1) simultaneous identification of compressional and shear wave velocities; and 2) least-squares ... -
Non-Linear Constraints with Application to Self-Potential Source Inversion
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2006-05)We investigate the use of non-linear constraints for geophysical inverse problems, with specific examples applied to source inversion of self-potential data. Typical regularization methods often produce smooth solutions ... -
Nonhyperbolic Reflection Moveout For Azimuthally Anisotropic Media
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1999)Reflection moveout in azimuthally anisotropic media is not only azimuthally dependent but it is also nonhyperbolic. As a result, the conventional hyperbolic normal moveout (NMO) equation parameterized by the exact NMO ... -
Nonhyperbolic reflection moveout for orthorhombic media
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2002)Reflection moveout in azimuthally anisotropic media is not only azimuthally dependent but it is also nonhyperbolic. As a result, the conventional hyperbolic normal moveout (NMO) equation parameterized by the exact NMO ... -
Nonlinear Conjugate Gradients Algorithm For 2-D Magnetotelluric Inversion
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2000)We investigate a new algorithm for computing regularized solutions of the two-dimensional magnetotelluric inverse problem. The algorithm employs a nonlinear conjugate gradients (NLCG) scheme to minimize an objective ... -
Nonlinear Frechet derivative and its De Wolf approximation
(Massachusetts Institute of Technology. Earth Resources Laboratory, 2012)We introduce and derive the nonlinear Frechet derivative for the acoustic wave equation. It turns out that the high order Frechet derivatives can be realized by consecutive applications of the scattering operator and a ... -
Nonlinear Refraction Traveltime Tomography
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1996)We identify a few unique issues that are important for performing a nonlinear refraction traveltime tomography effectively. These include accuracy of traveltime and raypath calculation for a turning ray and physical ... -
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 ...
