Phase-encoding-based reverse time migration of multiples

Reverse time migration of multiples (RTMM) can supply migration results with wider illumination and broader wavenumber spectra than conventional reverse time migration (RTM) of primaries. However, crosstalk artifacts caused by interferences between unrelated multiples severely degrade the imaging quality of multiples. To address the crosstalk problems, RTM using controlled-order multiples (RTM-CM) was proposed. In RTM-CM, different-order multiples are first isolated using the multiples decomposition strategy, followed by migration procedures of consecutive-order multiples. By exploiting RTM-CM, most energetic crosstalks can be significantly eliminated. However, N individual migrations need to be conducted for staking in RTM-CM, thereby causing an N-fold increase in computational costs, in which N is the maximum order of considered multiples. To reduce computation costs and inherit the benefits of controlled-order multiple imaging, we developed a phase-encoding-based migration approach for multiples. This method first phase encodes different-order multiples by randomly modifying time shifts and polarity reversals. And then the encoded multiples with orders of 0 to N -1 are stacked to form the forward-propagating supergathers, whereas the backward-propagating supergathers comprise encoded multiples with orders of 1 to N. Finally, by using supergathers, the proposed approach can simultaneously accomplish migrations of all isolated-order multiples, which significantly improves computational efficiency. Numerical examples on two synthetic and one field datasets corroborate that the proposed approach can considerably enhance imaging quality by suppressing crosstalks and reducing computational costs.