Application of AVO Method to Analyze the Seismic Characteristics of Gas Hydrate Offshore Southwestern

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Methane hydrate
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.598.7685; http://2007tga.cgu.org.tw/cdrom/Oral (PDF)/ER1-5A-03.pdf

Marine seismic reflection data collected from offshore southwestern Taiwan show prominent seismic bottom simulating reflectors (BSRs) that indicate the existence of gas hydrate in the seafloor sediment with free gas zone underneath. For the purpose of understanding the methane hydrate system (generation, migration and accumulation) as well as to delineate the methane hydrate reservoir properties, we used Amplitude Versus Offset (AVO) analysis of the seismic reflection data. AVO analysis is successfully used to discriminate between the presence of gas and lithologic variations in Bright Spot analysis. The theory behind AVO analysis finds its roots in Zoeppritz equations. These equations relate reflection coefficients and propagation angles. Qualitatively, seismic wave mode conversion is responsible for the dependence of amplitude anomalies in seismic data with respect to wavefront incidence angle or offset. This mode conversion is most evident with a large change in Poisson’s ratio, and this, for example, occurs when gas saturated rock meets water saturated rock. AVO analysis after migration has long been recognized as