Now showing items 33-52 of 456

    • An approach for predicting stress-induced anisotropy around a borehole 

      Fang, Xinding; Fehler, Michael; Zhu, Zhenya; Chen, Tianrun; Brown, Stephen; e.a. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2012)
      Formation elastic properties near a borehole may be altered from their original state due to the stress concentration around the borehole. This could result in a biased estimation of formation properties but could provide ...
    • Approximate Effects of Off-Center Acoustic Sondes and Elliptic Boreholes Upon Full Waveform Logs 

      Willis, M. E.; Toksoz, M. N.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Full waveform acoustic well logging has become instrumental to hydrocarbon exploration because of its ability to determine in situ velocity information for P and S waves as well as the attenuation (or absorption) of seismic ...
    • Approximate inversion of the wave-equation Hessian via randomized matrix probing 

      Letourneau, Pierre-David; Demanet, Laurent; Calandra, Henri (Massachusetts Institute of Technology. Earth Resources Laboratory, 2012)
      We present a method for approximately inverting the Hessian of full waveform inversion as a dip-dependent and scale-dependent amplitude correction. The terms in the expansion of this correction are determined by least-squares ...
    • Array-conditioned deconvolution of multiple component teleseismic recordings 

      Chen, C. -W.; Rondenay, Stephane; Miller, D. E.; Djikpesse, H. A. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2010-01-01)
      We investigate the applicability of an array-conditioned deconvolution technique, developed for analyzing borehole seismic exploration data, to teleseismic receiver functions and data preprocessing steps for scattered ...
    • Asymmetric Modes of Elastic Wave Propagation in a Fluid-Filled Borehole 

      Jinzhong, Zhang; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1985)
      A numerical investigation of asymmetric modes of elastic wave propagation in a fluid-filled borehole is treated in this paper. The dispersion curves of guided waves (called flexural waves) and synthetic microseismograms ...
    • Asymmetric source acoustic LWD for the improved formation shear velocity estimation 

      Chen, Tianrun; Wang, Bing; Zhu, Zhenya; Burns, Daniel R. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2009)
      Most acoustic LWD tools generate a single pure borehole mode (e.g., dipole or quadrupole) to estimate the formation shear velocity. We propose an approach where many borehole modes are generated and all the modes are ...
    • Asymmetric source acoustic LWD for the improved formation shear velocity estimation 

      Chen, Tianrun; Wang, Bing; Zhu, Zhenya; Toksoz, Daniel R. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2010)
      Most acoustic logging while drilling (LWD) tools generate a single pure borehole mode (e.g., dipole or quadrupole) to estimate the formation shear velocity. We propose an approach where multipole modes are generated ...
    • AVO Monitoring of CO[subscript 2] Sequestration 

      Brown, Stephen; Hagin, Paul; Bussod, Gilles (Massachusetts Institute of Technology. Earth Resources Laboratory, 2011)
      Standard geophysical methods for monitoring CO[subscript 2] injection have been proposed but many have severe limitations. In particular, while they can be used to monitor the presence or absence of CO[subscript 2] during ...
    • Azimuthal Offset-Dependent Attributes (AVO And FVO) Applied To Fracture Detection 

      Shen, Feng; Sierra, Jesus; Burns, Daniel R.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1999)
      Using the amplitude versus offset (AVO) and the frequency versus offset (FVO) information, the diagnostic ability of P-wave seismic data in fracture detection is investigated. The offset-dependent attributes (AVO and FVO) ...
    • A Bayesian framework for fracture characterization from surface seismic data 

      Zamanian, S. Ahmad; Fehler, Michael; Burns, Daniel R. (Massachusetts Institute of Technology. Earth Resources Laboratory, 2012)
      We describe a methodology for quantitatively characterizing the fractured nature of a hydrocarbon or geothermal reservoir from surface seismic data under a Bayesian inference framework. Fractures provide pathways for fluid ...
    • Borehole Acoustics and Logging and Reservoir Delineation Consortia 

      Burns, Daniel R. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1997)
      Research activity in the Borehole Acoustics and Logging/Reservoir Delineation Consortia continue to focus on the development of geophysical methods to detect and characterize geological conditions which control fluid ...
    • Borehole Effects On Downhole Seismic Measurements 

      Peng, Chengbin; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)
      An exact formulation for borehole coupling, which is valid for all frequencies and all azimuthally symmetric and nonsymrnetric components, is given in this paper. The borehole effects on downhole measurements are studied ...
    • Borehole Electroseismic Measurements In Dolomite: Identifying Fractures And Permeable Zones 

      Mikhailov, Oleg V.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1998)
      Measuring the electrical field induced by a borehole Stoneley wave is a new method for characterizing a rock formation around a borehole. Our field measurements demonstrate that the Stoneley-wave-induced electrical field ...
    • Borehole Resistivity Inversion 

      Garipova, Yulia V. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1997)
      In this paper we perform the inversion of borehole resistivity data using the software package developed by Western Atlas Logging Services, Houston, TX. Direct current resistivity methods, namely lateral sounding and ...
    • Borehole Seismic Source Radiation In Layered Isotropic And Anisotropic Media: Boundary Element Modeling 

      Dong, Wenjie; Bouchon, Michel; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)
      An algorithm based on the boundary element method is established for modeling seismic source radiation from open or cased boreholes in layered transversely isotropic (TI) media. The axis of symmetry of TI layers is assumed ...
    • Borehole Stoneley Wave Propagation Across Heterogeneous And Permeable Structures 

      Tang, X. M.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1991)
      This study investigates the propagation of borehole Stoneley waves across heterogeneous and permeable structures. By modeling the structure as a zone intersecting the borehole, a simple one-dimensional theory is formulated ...
    • Borehole Stoneley Wave Propagation Across Permeable Structures: Comparison Between Theory And Experiment 

      Zhu, Zhenya; Tang, Xiaoming; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)
      The attenuation of borehole Stoneley waves across a permeable structure (e.g., fractures or fracture zone) is correlated with the permeability of the structure. Using a simplified Biot theory, the structure can be modelled ...
    • Borehole Wave Propagation In Isotropic And Anisotropic Media I: Finite Difference Method 

      Cheng, Ningya; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)
      In this paper we developed a 3-D finite difference method to simulate wave propagations in an isotropic medium. The wave equation is formulated into the first-order hyperbolic equations by using velocity and stress and ...
    • Borehole Wave Propagation In Isotropic And Anisotropic Media II: Isotropic Formation 

      Cheng, Ningya; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)
      In this paper we apply the 3-D finite difference method to simulate borehole wave propagations in an isotropic formation. The scheme is tested in a fluid-filled borehole surrounded by the homogeneous elastic formation. ...
    • Borehole Wave Propagation In Isotropic And Anisotropic Media III: Anisotropic Formation 

      Cheng, Ningya; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)
      In this paper we extend the 3-D finite difference method to simulate wave propagations in an anisotropic medium. The scheme is tested in the homogeneous medium. The finite difference results agree excellently with the ...