• Login
    View Item 
    •   Home
    • Theses & Dissertations
    • 2015 - Mines Theses & Dissertations
    • View Item
    •   Home
    • Theses & Dissertations
    • 2015 - Mines Theses & Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Mines RepositoryCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    Login

    Mines Links

    Arthur Lakes LibraryColorado School of Mines

    Statistics

    Display Statistics

    Estimation of microseismic source parameters by anisotropic waveform inversion

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    JarilloMichel_mines_0052N_10680.pdf
    Size:
    1.071Mb
    Format:
    PDF
    Description:
    Estimation of microseismic source ...
    Download
    Author
    Jarillo Michel, Oscar
    Advisor
    TSvankin, I. D.
    Date issued
    2015
    Keywords
    waveform inversion
    microseismic
    anisotropy
    adjoint
    Microseisms
    Waves
    Inversion (Geophysics)
    Anisotropy
    
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/11124/17091
    Abstract
    In microseismic data processing, source locations and origin times are usually obtained using kinematic techniques, whereas moment-tensor estimates are typically based on linear inversion of P- and S-wave amplitudes. Waveform inversion (WI), which has been used primarily for high-resolution velocity analysis, has the potential to provide more accurate source parameters along with an improved velocity model by incorporating both phase and amplitude information. The first issue addressed in the thesis is efficient calculation of the gradient of the WI objective function with respect to the model parameters. Application of the adjoint-state method helps obtain closed-form expressions for the gradient with respect to the source location, origin time, and moment tensor. Computation of the forward and adjoint wavefields is performed with a finite-difference algorithm that handles elastic VTI (transversely isotropic with a vertical symmetry axis) models. Numerical examples illustrate the properties of the gradient for multicomponent data recorded by a vertical receiver array placed in homogeneous and horizontally layered VTI media. Then WI is implemented to estimate the location, origin time, and seismic moment tensor of microseismic sources embedded in 2D VTI media. Both a constant and variable step-length computed by line-search followed by the nonlinear conjugate method (NCG) are used for model updating. Although in the current algorithm the interval VTI parameters are assumed to be known, they can be included in WI at almost no additional cost. Velocity estimation, however, is likely to make the objective function more complicated and increase ambiguity of the inversion. Synthetic tests for data recorded by vertical receiver arrays show that it is possible to tightly constrain all source parameters, if a sufficiently accurate initial model is available. In particular, the source location in layered VTI media can be estimated simultaneously with the moment tensor. The resolution of event location, however, somewhat decreases when the origin time is unknown or there is an error in one of the VTI parameters.
    Rights
    Copyright of the original work is retained by the author.
    Collections
    2015 - Mines Theses & Dissertations

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Contact Us
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.