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Browsing Earth Resources Laboratory by Title

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  • Cheng, C. H.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
    Direct determination of formation shear wave travel time is impossible in "slow" formations where the shear wave velocity is lower than the borehole fluid (mud) velocity. However, the Stoneley waves in these formations are ...
  • Toksoz, M. Nafi; Wilkens, R. H.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
    In boreholes where formation shear velocity is lower than borehole fluid velocity neither refracted shear waves nor pseudo-Rayleigh waves can propagate. When frequency response of the sonde does not extend to low frequencies ...
  • Lee, Jung Mo; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1995)
    Open fractures are of interest in many areas such as ground water contamination, hazardous waste disposal, oil and gas recovery, and geothermal energy extraction. In borehole geophysics and engineering, fractures are ...
  • Meredith, J . A.; Cheng, C. H.; Wilkens, R. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1987)
    The inversion technique presented in this volume (Cheng, 1987) that simultaneously inverts full waveform acoustic logs for shear wave velocity (V[subscript 3]) and compressional wave attenuation (Q[subscript p]) was applied ...
  • Sen, Pabitra; Liu, Yun; Leu, Gabriela; Cory, David G. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2001)
    NMR methods are widely used to probe the structure and fluid dynamics of porous materials including such diverse materials as cheese and chocolate, cosmetics and pharmaceuticals, solvents in resins and soft matter, biological ...
  • Huang, Xiaojun; Burns, Daniel R.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1998)
    In this paper, we demonstrate that dispersion analysis of cross-dipole data has promising potential not only for differentiating stress-induced anisotropy from intrinsic anisotropy, but also for providing information on ...
  • Nolte, Bertram; Rao, Rama; Huang, Xiaojun (Massachusetts Institute of Technology. Earth Resources Laboratory, 1997)
    In this paper we first present a technique for measuring dispersion curves from array data, that is both simple and efficient. We demonstrate its performance on both synthetic and field data. We then use the technique to ...
  • Tubman, Kenneth M.; Cole, Stephen P.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
    The dispersion relations and impulse response. are calculated for a geometry consisting of an arbitrary number of coaxial annuli surrounding a central cylinder. The annuli may be either solid or fluid. The formulation ...
  • Rao, Rama V. N.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 2005)
    A technique for estimating the dispersion characteristics of propagating waves as measured by an array is detailed. The technique consists of bandpass filtering the data through a filterbank and then processing the filtered ...
  • Song, Fuxian; Toksoz, M. Nafi; Li, Junlun (Massachusetts Institute of Technology. Earth Resources Laboratory, 2010)
    Downhole microseismics has gained in popularity in recent years as a way to characterize hydraulic fracturing sources and to estimate in-situ stress state. Conventional approaches only utilize part of the information ...
  • Dong, Wenjie; Schmitt, Denis P. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1993)
    Concise and numerically feasible dynamic and static Green's functions are obtained in dyadic form by solving the wave equation and the equilibrium equation with general source distribution in transversely isotropic (TI) ...
  • Zhao, Xiaomin; Cheng, C. H.; Tang, Xiaoming; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)
    This study investigates the frequency-dependence of fluid flow in heterogeneous porous media using the theory of dynamic permeability and a finite-difference method. Given a permeability distribution, the dynamic ...
  • Tang, X. M.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1988)
    The attenuation of Stoneley waves by a borehole fracture are closely related to fluid flow in the fracture. We consider the dynamic response of a viscous fluid in a horizontal fracture to the oscillating pressure excitation ...
  • Tang, X. M.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1990)
    Stoneley waves in permeable boreholes are diagnostic of formation permeability because their propagation is affected by the dynamic fluid flow at the borehole wall. We characterize this flow using the concept of dynamic ...
  • Haartsen, Matthijs W.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1996)
    In a porous medium saturated with a fluid electrolyte, mechanical and electromagnetic disturbances are coupled. The coupling is electrokinetic in nature since it is due to an excess of electrolyte ions that exist in an ...
  • Zhan, Xin; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 2007-05-27)
    The microstructure of a porous medium and physical characteristics of the solid and the fluids that occupy the pore space determine the macroscopic transport properties of the medium. The computation of macroscopic ...
  • Edie, Margaret S.; Olson, John F.; Burns, Daniel R.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 2000)
    Realistic simulations of flow in porous media are dependent upon having a three-dimensional, high resolution image of pore structure which is difficult to obtain. So, we ask the question, "How fine a resolution is necessary ...
  • Huang, Xiaojun; Burns, Daniel R.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 2001)
    The theory of acoustoelasticity provides direct link between the change of elastic wave velocities and residual stresses in solids. The general theory of acoustoelasticity is reviewed. A number of experimental measurements ...
  • Tao, Guo; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1996)
    In recent years, borehole Stoneley wave amplitude and reflectivity have been used for estimating formation permeability based on the strong correlation between Stoneley wave attenuation, reflectivity and formation fluid ...
  • Tang, X. M.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1991)
    A detailed study is carried out to investigate the effects of an acoustic logging tool on the propagation characteristics of Stoneley waves in both elastic and porous formations. In an elastic formation, the presence of ...
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