Examinando por Materia "Seismic prospecting"

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    Analysis of the stability and dispersion for a Riemannian acoustic wave equation
    (ELSEVIER SCIENCE INC, 2019-01-15) Quiceno, H. R.; Arias, C.; Quiceno, H. R.; Arias, C.; Universidad EAFIT. Departamento de Ciencias; Matemáticas y Aplicaciones
    The construction of images of the Earth's interior using methods as reverse time migration (RTM) or full wave inversion (FWI) strongly depends on the numerical solution of the wave equation. A mathematical expression of the numerical stability and dispersion for a particular wave equation used must be known in order to avoid unbounded numbers of amplitudes. In case of the acoustic wave equation, the Courant–Friedrich–Lewy (CFL) condition is a necessary but is not a sufficient condition for convergence. Thus, we need to search other types of expression for stability condition. In seismic wave problems, the generalized Riemannian wave equation is used to model their propagation in domains with curved meshes which is suitable for zones with rugged topography. However, only a heuristic version of stability condition was reported in the literature for this equation. We derived an expression for stability condition and numerical dispersion analysis for the Riemannian acoustic wave equation in a two-dimensional medium and analyzed its implications in terms of computational cost. © 2018 Elsevier Inc.
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    Application of the continuous wavelet transform in the extraction of directional data on RTM imaging condition wavefields
    (Ecopetrol, 2018-01-01) Paniagua-Castrillón J.-G.; Quintero-Montoya O.-L.; Universidad EAFIT. Escuela de Ciencias; Modelado Matemático
    Low-frequency artifacts in reverse time migration result from unwanted cross-correlation of the source and receiver wavefields at nonreflecting points along ray-paths. These artifacts can hide important details in migrated models and increase poor interpretation risk. Some methods have been proposed to avoid or reduce the number of these artifacts, preserving reflections, and improving model quality, implementing other strategies such as modification of the wave equation, proposing other imaging conditions, and using image filtering techniques. One of these methods uses wavefield decomposition, correlating components of the wavefields that propagate in opposite directions. We propose a method for extracting directional information from the RTM imaging condition wavefields to obtain characteristics allowing for better, more refined imaging. The method works by separating directional information about the wavefields based on the continuous wavelet transform (CWT), and the analysis of the main changes on the frequency content revealed within the scalogram obtained by a Gaussian wavelet family. Through numerical applications, we demonstrate that this method can effectively remove undesired artifacts in migrated images. In addition, we use the Laguerre-Gauss filtering to improve the results obtained with the proposed method. © 2018 Ecopetrol S.A. All Rights Reserved.
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    Estimación de las direcciones de fracturas basada en la técnica de la elipse NMO equivalente
    (Universidad EAFIT, 2011) Pérez Valencia, Felipe Andrés; Camacho, Germán
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    Seismic Data compression using 2D Lifting-Wavelet algorithms
    (Universidad EAFIT, 2014-12-19) Fajardo Ariza, Carlos Augusto; Reyes Torres, Oscar Mauricio; Ramirez Silva, Ana Beatriz; Ecopetrol; Universidad Industrial de Santander; Purdue University
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    Simulador de ondas P utilizando el paquete Seismic Un *X
    (Universidad EAFIT, 2009) Gutarra Vélez, Eduardo; Lorduy Gómez, Roberto
    La carrera de ingeniería de sistemas tiene la capacidad de interactuar con otras disciplinas poniendo a su disposición tecnologías que simplifiquen, agilicen o mejoren tareas que le son afines -- La educación, propiamente dicha, es una de las disciplinas que se puede beneficiar de la ingeniería de sistemas para ayudar a explicar temas por medio de la visualización y la simulación en donde el estudiante pueda poner en práctica lo que está aprendiendo -- El proyecto que se va a introducir cumple su propósito en este ámbito, pues la aplicación que se va a realizar apoyará en la enseñanza del comportamiento de las ondas sísmicas P -- La contribución que se hizo en este trabajo consiste en la implementación de una interfaz gráfica de usuario que coordina el funcionamiento de un conjunto de programas que provienen de un paquete llamado Seismic Un*X el cual es utilizado por geólogos, geofísicos, ingenieros de petróleo y civiles entre otros, para estudiar el fenómeno de propagación de ondas sísmicas al interior de la tierra
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    The Spectral Cell Method in Nonlinear Earthquake Modeling
    (Universidad EAFIT, 2016) Giraldo Cuartas, Daniel; Restrepo Sánchez, Doriam Leidin
    In this study we focus at examining an efficient high order finite element strategy to compute the dynamic response of heterogeneous basins under nonlinear soil behavior subjected to point-source earthquake events -- The numerical technique known as the Spectral Cell Method (SCM) combines Fictitious-Domains concepts with the Spectral-version of the finite element method to accurately solve the wave equations in heterogeneous geophysical domains -- We tested the SCM in physically and computationally challenging domains namely, (i) a semi-elliptical basin, and (ii) an undulated basin embedded in a half-space with several irregular geological structures with different material discontinuities -- Nonlinear behavior is considered by implementing a Mohr-Coulomb, and a Drucker- Prager yielding criteria -- We benchmark our simulations with results obtained using MIDAS GTS NX, a finite element tool for geotechnical applications based upon traditional boundary-fitted meshing techniques