Download or read book Acoustic Full waveform to Elastic Pre stack Seismic Inversion of the Yakutat Terrane Gulf of Alaska written by Hala Alqatari and published by . This book was released on 2018 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Yakutat-North American collision in the Gulf of Alaska has developed a complex subduction zone followed by major deformations such as the Chugach-St Elias mountain range creation, intensified exhumation, fold and thrust-fault formation. I generate a compressional velocity model of the Yakutat microplate using two-dimensional acoustic and isotropic time-domain full waveform inversion (FWI) of marine seismic reflection and refraction data from the STEEP project (ST. Elias Erosion/tectonics Project). FWI is a non-linear data-fitting algorithm that aims to recover subsurface parameters from the recorded seismic wavefield. Seismic wave propagation along the Yakutat terrane is simulated using a staggered-grid finite difference modeling scheme. Drawbacks associated with FWI is cycle skipping during the minimization process, which results in converging to the wrong velocity model. Starting with a good initial model that contains the low-frequency information can help mitigate this issue. The starting velocity model input to FWI in this case is generated by a traveltime tomographic inversion of ocean-bottom seismometer and streamer seismic data. Data preconditioning includes muting, filtering, noise removal and amplitude rescaling of the field seismic data to match the corresponding amplitudes of the synthetic traces. The forward model is able to produce a good match between the observed and the modeled wavefield within half the propagated wavelength. I use the FWI result, which shows good correlation with the industry well, as an input to two additional seismic inversion methods: acoustic post-stack and elastic pre-stack seismic inversion in order to recover shear impedance and density models along the seismic line. Extending the problem to the elastic medium is important to support more advanced seismic interpretation. Both techniques were able to produce higher-resolution images of the Yakutat terrane that are well correlated with the well response. Structural complexities identified in the generated models include the northwest-dipping Pamplona fault system, the offshore folding zone, thickening of the Yakutat basement and, lastly, significantly lower velocities in the Poul Creek formation compared to the younger Yakataga formation, which may be attributed to high-fluid pressure within that formation.
Download or read book Robust Pre stack Seismic Waveform Inversion for Acoustic Elastic Isotropic and Anisotropic Media Parameters written by Amit Padhi and published by . This book was released on 2006 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic prestack waveform inversion is an ill posed, nonlinear inverse problem with nonunique solutions. Additionally the problem suffers from the existence of multiple local optima in the topography of the data misfit measure and high computational cost. These problems get aggravated as the number of model parameters to be estimated per layer or grid point increase. The number of parameters per layer or grid point depends on the assumptions necessary for modeling the seismic data. Hence it is necessary to investigate the physical processes affecting the observed data significantly in specific situations and then develop appropriate inversion methodologies. In this dissertation I apply a local inversion scheme based on nonlinear least squares (NLS) approach to invert one dimensional synthetic and one and two dimensional field seismic prestack waveform data in an area with sparse direct measurements to estimate sound speed in the oceanic water column. This is because seismic propagation is acoustic and isotropic in water and density does not change significantly. The two dimensional results are further compared to that obtained using a completely global approach. I also develop an adjoint state method based Jacobian computation for the NLS scheme to be applied to the problem of acoustic seismic inversion. Next, I investigate and propose an efficient method to monitor CO2 sequestrated reservoirs by combining multiphase flow simulation results with seismic modeling. Finding that such a monitoring scheme would require multicomponent seismic waveform data inversion under elastic anisotropic assumptions, I cast the inverse problem as a multiobjective optimization problem and solve it using a nondominated sorting genetic algorithm. Synthetic and real data tests show that while local inversion schemes work reasonably well for acoustic inversion, elastic anisotropic inversion requires a global approach utilizing multicomponent data. Hence monitoring CO2 sequestrated reservoirs efficiently using proxy stack of anisotropic layers requires the second approach. I also show that the NLS approach can be made efficient using the adjoint state method if the number of model parameters to be estimated is large enough. In the other case, computing the Jacobian using the traditional method and parallelization is preferable and can be implemented easily.
Download or read book Multi component Seismic Modeling and Robust Pre stack Seismic Waveform Inversion for Elastic Anisotropic Media Parameters written by Tao Li and published by . This book was released on 2016 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Consideration of azimuthal anisotropy, at least to an orthorhombic symmetry is important in exploring the naturally fractured and unconventional hydrocarbon reservoirs. Full waveform inversion of multicomponent seismic data can, in principle, provide more robust estimates of subsurface elastic parameters and density than the inversion of single component (P wave) seismic data. In addition, azimuthally dependent anisotropy can only be resolved by carefully studying the multicomponent seismic displacement data acquired and processed along different azimuths. Such an analysis needs an inversion algorithm capable of simultaneously optimizing multiple objectives, one for each data component along each azimuth. In this dissertation, I propose a novel multiobjective methodology using a parallelized version of NSGA II for waveform inversion of multicomponent seismic data along two azimuths. The proposed methodology is also an improvement of the original NSGA II in overall computational efficiency, preservation of population diversity, and rapid sampling of the model space. Next, the proposed methodology is applied on wide azimuth and multicomponent vertical seismic profile (VSP) data to provide reliable estimation of subsurface anisotropy at and near the well location. Prestack waveform inversion was applied to the wide-azimuth multicomponent VSP data acquired at the Wattenberg Field, located in Denver Basin of northeastern Colorado, USA, to characterize the Niobrara formation for azimuthal anisotropy. By comparing the waveform inversion results with an independent study that used a joint slowness-polarization approach to invert the same data, we conclude that the waveform inversion is a reliable tool for inverting the wide-azimuth multicomponent VSP data for anisotropy estimation. Last but not least, an anisotropic elastic three-dimensional scheme for modeling the elastodynamic wavefield is developed in order to go beyond the 1D layering assumption being used in previous studies. The method uses quadratic tetrahedral elements to discretize the model in space, Newmark family of time integration scheme to discretize in time, and a perfectly matched layer as the absorbing boundary condition. Various preconditioned conjugate gradient approaches were tested and implemented in the algorithm to improve the numerical efficiency of the finite element solver and the entire methodology was optimized to run efficiently in a parallel computing architecture. By computing synthetic seismic responses for a homogeneous medium and for a layered anisotropic medium and comparing results with other analytical and numerical solutions, the validity of the methodology was also verified for numerical accuracy.
Download or read book Wave Interactions As a Seismo acoustic Source written by Alick C. Kibblewhite and published by Springer. This book was released on 2006-04-10 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a comprehensive, theoretical account of the wave-wave interaction process responsible for high acoustic noise levels, including: a geometric description of the interaction mechanism, which provides the basis for a full-wave analysis of the source process, the inclusion of both the monogeneous and inhomogeneous components of the wave-induced pressure field in the analytical description of the source, an examination of the relative contributions of the sum and difference-frequency components of the wave interaction process, the removal of the deep-water assumption of earlier analyses, and the development of an "exact" analytical expression which allows the source function of the wave-induced pressure field to be calculated over the whole frequency-wave number domain.
Download or read book Seismic Migration written by A. J. Berkhout and published by . This book was released on 1982 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acoustic Full Waveform Inversion of Marine Reflection Seismic Data written by Anna Przebindowska and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Elastic Full Waveform Inversion of Multi component Ocean bottom Cable Seismic Data written by Timothy John Sears and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic and Morphologic Analysis of the Gulf of Alaska Yakutat Margin written by John Marshall Swartz and published by . This book was released on 2014 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: The active St. Elias Orogen in southern Alaska was created by collision of the offshore Yakutat Terrane with North America. These mountains exhibit the highest coastal relief in the world and also are home to temperate tidewater glaciers, one of the most powerful erosive agents known. Glaciation in Southern Alaska has occurred since the Miocene, but climatic shifts associated with the intensification of Northern Hemisphere glaciation at ~2.5 Ma and the mid-Pleistocene transition at ~1 Ma have led to drastic increases in glacial erosion and associated offshore sediment transport and deposition. The Yakutat continental shelf has hosted ice streams during glacial advances since the mid-Pleistocene, but it is only recently that ice has reached the continental shelf edge itself. Quantitative morphologic analysis finds significant variability along the slope, with an relatively gentle gradient trough mouth fan building off the Yakutat Sea Valley, a shelf-crossing glacial trough, due to massive sediment supply from the heart of the St. Elias Orogen, while farther to the east the extremely steep continental margin is heavily gullied and sediment bypasses the slope reaching the offshore Surveyor fan. Seismic stratigraphy indicates that ice streams first reached the shelf edge with the mid-Pleistocene climate transition, a shift from 41 ka to 100 ka glacial-interglacial climate cycles. This increase in glacial durations allowed not only the ice to sustain advances to the shelf edge, but led to amplified erosion and climate-tectonic feedback effects.
Download or read book Elastic Full Waveform Inversion of Near Surface Seismic Data Incorporating Topography written by André Marc Nuber and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Processing and Interpretation of Seismic Data in the Northern Gulf of Alaska Offshore Yakutat written by Julie K. Zweig and published by . This book was released on 1985 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modeling of Seismic Wave Propagation written by Johan O. A. Robertsson and published by SEG Books. This book was released on 2012 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: The decades following SEG's 1990 volume on numerical modeling showed a step change in the application and use of full wave equation modeling methods enabled by the increase in computational power. Full waveform inversion, reverse time migration, and 3D elastic finite-difference synthetic data generation are examples. A searchable CD is included.
Download or read book Full Waveform Seismic Inversion Using Adjoint Methods for the Japanese Region written by and published by . This book was released on 2014 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Resolution written by A. J. Berkhout and published by . This book was released on 1984 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Rupture Process of Large Earthquakes Along Convergent Margins written by Charles Hershey Estabrook and published by . This book was released on 1992 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Pre stack Migration of Profiles written by Allan Jacobs and published by . This book was released on 1982 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Space Time Methods for Acoustic Waves with Applications to Full Waveform Inversion written by Johannes Ernesti and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Full Waveform Inversion in an Anisotropic World written by Tariq A. Alkhalifah and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
