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Browsing Earth Resources Laboratory by Title

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  • Imhof, Matthias G.; Toksoz, M. Nafi; Burch, Charles I.; Queen, John H. (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 ...
  • AI-Dajani, AbdulFattah; Toksoz, M. Nafi (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 ...
  • Al-Dajani, A.; Toksoz, M. Nafi (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 ...
  • Rodi, William L.; Mackie, Randall L. (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 ...
  • Minsley, Burke J.; Ajo-Franklin, Jonathan B.; Dale, Frank (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 ...
  • Wu, Ru-Shan; Zheng, Yingcai (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 ...
  • Zhang, Jie; Toksoz, M. Nafi (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 ...
  • Tezuka, Kazuhiko (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 ...
  • Johnson, Paul; Pearce, Fred; Willis, Mark E.; Burns, Daniel R.; Toksoz, M. Nafi (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 ...
  • Hoop, Martijn de; Willis, Mark E.; Lu, Rongrong; Burns, Daniel R.; Toksoz, M. Nafi; Campman, Xander (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 ...
  • deHoop, Maarten V.; Willis, Mark E.; Lu, Rongrong; Campman, Xander; Toksoz, M. Nafi; Zhang, Yang (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 ...
  • Zhang, Jinzhong; Cheng, C. H. (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 ...
  • Paillet, Frederick L.; Cheng, C. H. (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 ...
  • Al Muhaidib, Abdulaziz M.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 2012)
    Direct and scattered surface waves contain almost 90% of the seismic energy. They often obscure weak primary reflections and can severely degrade the final subsurface image quality. Therefore, they present great challenges ...
  • Al Muhaidib, Abdulaziz; Toksoz, M. Nafi (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 ...
  • Zhang, Yang; Song, Fuxian; Toksoz, M. Nafi (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 ...
  • Smith, Wave; Zhan, Xin; Schwartz, Larry; Morgan, Frank Dale; Toksoz, M. Nafi (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 ...
  • Bouchon, Michel (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 ...
  • Zhang, Yang; Nave, Jean-Christophe; Toksoz, M. Nafi (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 ...
  • Song, Limin; Deffenbaugh, Max; Zhang, Yang; Toksoz, M. Nafi (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 ...
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