Now showing items 73-92 of 456

    • Detecting medium changes from coda by interferometry 

      Poliannikov, Oleg V.; Malcolm, Alison E. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2010)
      In many applications, sequestering CO[subscript 2] underground for example, determining whether or not the medium has changed is of primary importance, with secondary goals of locating and quantifying that change. We ...
    • Detection and Characterization of Fractures from Generation of Tube Waves 

      Hardin, Ernest; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1985)
      Field testing has been conducted to evaluate a model which predicts the permeability and orientation of a permeable zone, in a deep water well in crystalline rock. Tube waves are generated by seismic P-waves incident on ...
    • Detection Of Fracture Orientation Using Azimuthal Variation Of P-Wave Avo Responses 

      Perez, Maria Auxiliadora; Gibson, Richard L., Jr. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1997)
      Azimuthally-dependent P-wave AVO (amplitude variation with offset) responses can be related to open fracture orientation and have been suggested as a geophysical tool to identify fracture orientation in fractured oil and ...
    • Detection of Open Fractures with Vertical Seismic Profiling 

      Beydoun, W. B.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984-01-01)
      In Vertical Seismic Profiling surveys tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The problem of generation of these waves by a non-normal incident P wave for an ...
    • Detection Of Subsurface Fractures And Permeable Zones By The Analysis Of Tube Waves 

      Beydoun, W. B.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      In Vertical Seismic Profiling tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The amplitude of tube waves is dependent upon the formation permeability, the length of ...
    • Determination of Formation Properties in Cased Boreholes Using Full Waveform Acoustic Logs 

      Tubman, Kenneth M.; Cheng, C. H.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Wave propagation in bonded and unbonded cased boreholes is examined through the calculation cif synthetic full waveform acoustic logs. The models consist of a central fluid borehole surrounded by a number of fluid and solid ...
    • Determination Of In-Situ Permeability From Tube Wave Velocity And Attenuation 

      Burns, D. R.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1986)
      Recent investigations by a number of different authors have shown that the phase velocity and attenuation of the tube (Stoneley) wave in the borehole is correlated with in situ permeability. Specifically, velocity decreases ...
    • Determination of Near-Surface Anisotropy From Surface Electromagnetic Data 

      Al-Dajani, AbdulFattah; Morgan, Frank Dale; Toksoz, M. Nafi; Repperty, Philip (Massachusetts Institute of Technology. Earth Resources Laboratory, 2001)
      Ground penetrating radar (GPR) signatures, such as reflection moveout, are sensitive to the presence of azimuthal anisotropy. Azimuthal anisotropy can occur as an intrinsic property of the medium and/or due to the presence ...
    • Determination of Shear Wave Velocities in "Slow" Formations 

      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 ...
    • Determination of Shear Wave Velocity and Attenuation From Waveforms in Low Velocity Formations 

      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 ...
    • Determination Of The Orientation Of Open Fractures From Hydrophone VSP 

      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 ...
    • Determining Shear Wave Velocities in Soft Marine Sediments 

      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 ...
    • Diffusive MASS NMR Studies of Transport in Porous Materials 

      Liu, Yun; Leu, Gabriela; Cory, David G.; Sen, Pabitra (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 ...
    • Dispersion Analysis Of Cross-Dipole Data 

      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 ...
    • Dispersion Analysis Of Split Flexural Waves 

      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 ...
    • Dispersion Curves and Synthetic Microseismograms in Unbonded Cased Boreholes 

      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 ...
    • Dispersive Wave Analysis – Method and Applications 

      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 ...
    • Double-beam stacking to infer seismic properties of fractured reservoirs 

      Zheng, Yingcai; Fang, Xinding; Fehler, Michael; Burns, Daniel R. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2011)
      We develop a theory for using 3D beam interference to infer scattering properties of a fractured reservoir using reflected seismic P data. For the sake of simplicity, we use Gaussian beams. The scattering properties are ...
    • Double-Difference Waveform Inversion of 4D Ocean Bottom Cable Data: Application to Valhall, North Sea 

      Yang, Di; Fehler, Michael; Malcolm, Alison E.; Liu, Faqi; Morton, Scott (Massachusetts Institute of Technology. Earth Resources Laboratory, 2013)
      Changes in reservoir properties resulting from extracting hydrocarbons and injecting fluid are critical to optimize production. These properties can be characterized using waveform inversions of time-lapse seismic data. ...
    • Downhole microseismic monitoring of hydraulic fracturing: a full-waveform approach for complete moment tensor inversion and stress estimation 

      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 ...