Download or read book Observations Amd Modeling of Fracture related Seismic Velocity and Attenuation Anisotropy from Multiazimuthal Reverse VSPs written by E. Liu and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismology of Azimuthally Anisotropic Media and Seismic Fracture Characterization written by I. D. T︠S︡vankin and published by SEG Books. This book was released on 2011 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents an analysis of seismic signatures for azimuthally anisotropic media and shows anisotropic inversion/processing methods for wide-azimuth reflection data and VSP surveys. The focus is kinematic parameter-estimation techniques; the prestack amplitudes section includes AVO and attenuation coefficients; field examples are included.

Download or read book Multi component VSP Analysis for Applied Seismic Anisotropy written by Colin MacBeth and published by Elsevier. This book was released on 2002 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vertical seismic profile, acquired with an array of 3C receivers and either a single source or several arranged in a multi-component configuration, provides an ideal high fidelity calibration tool for seismic projects involved in the application of seismic anisotropy. This book catalogues the majority of specialized tools necessary to work with P-P, P-S and S-S data from such VSP surveys at the acquisition design, processing and interpretation stages. In particular, it discusses 3C, 4C, 6C and 9C VSP, marine and land surveys with near and multiple offsets (walkways), azimuths (walkarounds) or a combination of both. These are considered for TIH or TIV flavours of seismic anisotropy arising from cracks, fractures, sedimentary layering, and shales. The anisotropic adaptation of familiar seismic methods for velocity analysis and inversion, reflected amplitude interpretation, are given together with more multi-component specific algorithms based upon the principles dictated by the vector convolutional model. Thus, multi-component methods are described that provide tests and compensation for source or receiver vector fidelity, tool rotation correction, layer stripping, near-surface correction, wavefield separation, and the Alford rotation with its variants. The work will be of interest to geophysicists involved in research or the application of seismic anisotropy using multi-component seismic.

Download or read book Multi Attribute Seismic Rock Physics Approach to Characterizing Fractured Reservoirs written by Gary Mavko and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that fracturing is likely to be more intense near faults--sometimes referred to as the damaged zone. Yet another constraint, based on world-wide observations, is that the maximum likely fracture density increases with depth in a well-defined way. Defining these prior constrains has several benefits: they lead to a priori probability distributions of fractures, that are important for objective statistical integration; they limit the number of geologic hypotheses that need to be theoretically modeled; they provide plausible models for fracture distributions below the seismic resolution. The second element was theoretical rock physics modeling of optimal seismic attributes, including offset and azimuth dependence of traveltime, amplitude, and impedance signatures of anisotropic fractured rocks. The suggested workflow is to begin with an elastic earth model, based on well logs, theoretically add fractures to the likely facies as defined by the geologic prior information, and then compute synthetic seismic traces and attributes, including variations in P and S-wave velocities, Poisson's ratio, reflectivity, travel time, attenuation, and anisotropies of these parameters. This workflow is done in a Monte-Carlo fashion, yielding ranges of expected fracture signatures, and allowing realistic assessments of uncertainty to be honored. The third element was statistical integration of the geophysical data and prior constraints to map fracture intensity and orientations, along with uncertainties. A Bayesian framework was developed that allowed systematic integration of the prior constraints, the theoretical relations between fractures and their seismic signatures, and the various observed seismic observations. The integration scheme was successfully applied on an East Texas field site. The primary benefit from the study was the optimization and refinement of practical workflows for improved geophysical characterization of natural fractures and for quantifying the uncertainty of these interpretations. By presenting a methodology for integrating various types of information, the workflow will help to reduce the risk (and therefore the cost) of exploring for and recovering natural gas and oil reserves in fractured reservoirs.

Download or read book Reservoir Geophysics written by Robert E. Sheriff and published by . This book was released on 1993 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Keys of Egypt written by Lesley Adkins and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Keys of Egypt reveals the story of the scramble to decipher hieroglyphics, and the rediscovery of the Nile Valley after it had been closed to Europeans for nearly 2000 years.