AVO Numerical Simulation and Its Application to Gas Hydrate Identification in The Northern Slope of South China Sea
Presenter : Welayaturromadhona Advisor : How-Wei Chen
Abstract
Amplitude versus offset (AVO) analysis is a conventional seismic exploration technique in geophysical and lithological interpretation and has been widely used in onshore and offshore exploration. The AVO numerical method is used to 3 models of layered gas hydrate systems beneath seafloor to simulate the formation mechanism of BSR. The presence of evident ocean bottom simulating reflector (BSR) is closely related to the existence of free gas and the seismic profile “BSR” maybe is not uniquely linked with methane hydrate but only shows the existence of gas.
In this study, AVO analysis is applied to seismic profiles at drilling sites where hydrate samples have been recovered.The AVO responses of free gas, BSR, and gas hydrates are discussed and the AVO attributes in relation to gas hydrates are summarized. The resuts show that changes in intercept, gradient, fluid factor and poisson’s ratio clearly reflect : (i) location of free gas and the BSR, and (ii) spatial relations between blank zone, BSR, gas hydrate, and free gas.
Key words : AVO, gas hydrates, numerical simulation, BSR, south china sea.
References
Ecker C, Dvorkin J, Nur A M. Estimating the amount of gas hydrate and free gas from marine seismic data. Geophysics, 2000, 65(2): 565-573
Ruan, A.-G., J.-B. Li, F.-Y. Chu, and X.-Y.Li, 2006, AVO numerical simulation of gas hydrate reflectors beneath seafloor, Chinese J. Geophys. 49, 6, 1665-1675, DOI: 10.1002/cjg2.994.
Tinivella, U., and F. Accaino, 2000, Compressional velocity structure and poisson’s ratio in marine sediments with gas hydrate and free gas by inversion of reflected and refracted seismic data (South Shetland Islands, Antartica), Mar. Geol. 164,1-2, 13-27, DOI: 10.1016/S0025-3227(99)00123-1.
Yang, R., Yan, P., Wu, N., Sha, Z., and Liang, J., 2014, Application of AVO Analysis to Gas Hydrates Identification in the Northern Slope of the South China Sea, Acta Geophys. 62, 802-817.