PS and SP converted wave reflection coefficients and their application to time-lapse difference AVO

Shahin Jabbari and Kris Innanen

ABSTRACT

Multicomponent time-lapse amplitude variation with offset (AVO) may improve approximating time-lapse difference data. The difference data during the change in a reservoir from the baseline survey relative to the monitor survey are described for converted waves. We defined a framework for the difference reflection data, Δ R PS (θ) , and Δ R SP (φ) , in order of physical change or baseline interface contrast and time-lapse changes. A framework for linear and nonlinear time-lapse difference data are formulated using amplitude variation with offset (AVO) methods. The nonlinear higher order terms represent corrections appropriate for time-lapse problems especially for large contrasts cases. We conclude that in many plausible time-lapse scenarios the increase in accuracy associated with higher order corrections is non-negligible for converted wave. Furthermore the third order approximation terms in difference data emphasizes on the difference between exact Δ R PS (θ) , and Δ R SP (φ) .

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