HR: 17:20h
AN: NS34A-04    [Abstracts]
TI: Modeling of seismic amplitude to discriminate the effects of lithology and fluids in AVO anomalies in deep water of the Gulf of Mexico Basin.
AU: * Kerdan, T
EM: tkerdan@imp.mx
AF: INSTITUTO MEXICANO DEL PETROLEO, Eje Central Norte Lazaro Cardenas 152 Col San Bartolo Atepehuacan Gustavo A Madero, Mexico, DF 07730, Mexico
AU: Ramirez Ortega, C
EM: cortega@imp.mx
AF: INSTITUTO MEXICANO DEL PETROLEO, Eje Central Norte Lazaro Cardenas 152 Col San Bartolo Atepehuacan Gustavo A Madero, Mexico, DF 07730, Mexico
AU: Gonzalez Ibarra, A
EM: agibarra@imp.mx
AF: INSTITUTO MEXICANO DEL PETROLEO, Eje Central Norte Lazaro Cardenas 152 Col San Bartolo Atepehuacan Gustavo A Madero, Mexico, DF 07730, Mexico
AB: Recently the interest in deep water hydrocarbon exploration of the Gulf of Mexico Basin has increased. Hydrocarbon detection with AVO method in deep water presents greater ambiguity than at shallow depth. For this reason it is necessary to establish an strategy that reduces the risk of perforation associated with the interpretation of AVO anomalies. For the case of sandstone and shale, their petrophysical properties vary widely in the Gulf of Mexico Basin. For example, sandstones located at depths greater than 2-3 km can loose porosity due to cementation and hence this affect rock properties as impedance and Poisson coefficient, producing changes in seismic amplitudes. Reservoir sandstones can produce positive, negative o null reflections in the seismic sections. Throughout the Tertiary basins in the Gulf of México there are areas where acoustic impedance values of shales and gas sandstones are approximately equal. This means that those zones with hydrocarbon can appear as dim spot and are difficult to detect with conventional 3D seismic data. Hydrocarbon saturation affected the velocity of soft rocks at shallow depths, where sandstones is not cemented, but at greater depth when cementation increases susceptibility of rocks to fluid diminishes. For that reason it is important before AVO to make the elastic modeling to study the influence of different factors like mineralogy (obtained from analysis of well core and well logs), pore pressure, attenuation, illumination, anisotropy, etc. The studied elastic models show that it is often difficult to isolate the lithologic and fluid contribution to seismic response. To discriminate lithology from hydrocarbon it is necessary to make anelastic modeling (including attenuation), based on the fact that sands with gas produce attenuation anomaly whereas mineralogical changes do not. A detailed study of attenuation will allow to evaluate if the volume of gas in reservoir is commercial or not.
DE: 3025 Marine seismics (0935, 7294)
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly