%0 Journal Article
%T SEISMIC AND LITHOLOGICAL NEAR SURFACE CHARACTERISTICS OF AN AREA IN NORTH-EAST COLOMBIA
%A Sa¨²l-E Guevara
%A William-M Agudelo
%A Dany Rueda
%A Natalia Garc¨ªa
%J CT&F - Ciencia, Tecnolog¨ªa y Futuro
%D 2010
%I Instituto Colombiano del Petr¨®leo (ICP) - ECOPETROL S.A.
%X The seismic image of deep rock, interesting for the petroleum industry, can be distorted by the heterogeneous near-surface layers, characterized by low wave propagation velocity. The conventional methods used in counteracting this effect seem less effective in complex areas with rough topography such as those commonly found in Colombia, which are also affected by stronger tropical weathering. Characterization of the near-surface layer was conducted in this work with the purpose to investigate these relationships. Geological and geophysical methods were applied using data from a 2D seismic survey performed in the Catatumbo area of Colombia and seismic data and cutting samples analysis from a couple of 60 m depth wells (downhole surveys), drilled at rough surface locations. Wave propagation velocities were calculated by the application of tomography and refraction. Visual and laboratory assays such as granulometry and mineralogy were used in the analysis of the cutting samples. It was then possible to relate physical and lithological characteristics with properties of seismic response. Differences between the seismic response and the geological description were also observed and some uncertainties were identified. El estrato somero, heterog¨¦neo y caracterizado por la baja velocidad de propagaci¨®n de las ondas s¨ªsmicas, tiene influencia adversa en la imagen de los reflectores profundos obtenida a trav¨¦s del m¨¦todo s¨ªsmico, y de inter¨¦s para la industria petrolera. Los m¨¦todos tradicionalmente usados por la industria para contrarrestar este efecto parecen insuficientes en casos de zonas complejas y con topograf¨ªa abrupta, como sucede con frecuencia en Colombia. Con el objeto de contribuir a entender y superar estas limitaciones, en este trabajo se caracteriza el estrato somero usando metodolog¨ªas geol¨®gicas y geof¨ªsicas. Para este objeto, se utilizaron datos obtenidos en un levantamiento s¨ªsmico 2D efectuado en la cuenca del Catatumbo, y datos de dos pozos de estudio de 60 m de profundidad, en los cuales se midieron datos s¨ªsmicos directos y, adem¨¢s, se obtuvieron muestras de ripios, se midieron velocidades de propagaci¨®n de las ondas por varios m¨¦todos s¨ªsmicos y se hicieron ensayos visuales y de laboratorio sobre los datos de ripios. De esta manera, fue posible relacionar caracter¨ªsticas f¨ªsicas y litol¨®gicas con propiedades de la respuesta s¨ªsmica. Tambi¨¦n se encontraron diferencias y se identifican algunas incertidumbres al respecto.
%K m¨¦todos s¨ªsmicos
%K correcciones est¨¢ticas
%K meteorizaci¨®n
%K suelos
%K estratos
%K registros de pozo
%K geolog¨ªa compleja
%K datos s¨ªsmicos
%K s¨ªsmica 2D
%K ondas s¨ªsmicas
%K cuenca del Catatumbo
%K velocidad de ondas
%K Seismic methods
%K static corrections
%K weathering
%K soils
%K strata
%K well logs
%K complex geology
%K seismic data
%K 2D seismic
%K seismic waves
%K Catatumbo basin
%K wave velocity
%U http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0122-53832010000100002