Double plane‐wave reverse‐time migration

Abstract

We develop a new time‐domain reverse‐time migration method called double plane‐wave reverse‐time migration that uses plane‐wave transformed gathers. Original shot gathers with appropriate data acquisition geometry are double slant stacked into the double plane‐wave domain with minimal slant stacking artefacts. The range of plane‐wave components needed for migration can be determined by estimating the maximum time dips present in shot gathers. This reduces the total number of input traces for migration and increases migration efficiency. Unlike the pre‐stack shot‐profile reverse‐time migration where the number of forward propagations is proportional to the number of shots, the number of forward propagations needed for the proposed method remains constant and is relatively small even for large seismic datasets. Therefore, the proposed method can improve the efficiency of the migration and be suitable for migrating large datasets. Double plane‐wave reverse‐time migration can be performed for selected plane‐wave components to obtain subsurface interfaces with different dips, which makes the migration method target oriented. This feature also makes the method a useful tool for migration velocity analysis. For example, we are able to promptly obtain trial images with nearly horizontal interfaces and adjust velocity models according to common image gathers. Seismic signal coming from steeply dipping interfaces can be included into the migration to build images with more detailed structures and higher spatial resolution as better velocity models become available. Illumination compensation imaging conditions for the proposed method are also introduced to obtain images with balanced amplitudes.

Frequency‐domain double‐plane‐wave least‐squares reverse time migration

“…A frequency–DPW data set is a fully decomposed data set where original time domain shot gathers are decomposed into frequencies, source plane waves and receiver plane waves via the DPW transform (Tatalovic, Dillen and Fokkema ; Stoffa et al . ; Zhao, Sen and Stoffa ). Various migration methods utilizing DPW data have been introduced.…”

“…To make the data domain least-squares RTM more computationally affordable, we seek to implement least-squares RTM using compact frequency-ray parameter data, which is also known as the frequency-double-plane-wave (DPW) data (Zhao, Sen and Stoffa 2014). A frequency-DPW data set is a fully decomposed data set where original time domain shot gathers are decomposed into frequencies, source plane waves and receiver plane waves via the DPW transform (Tatalovic, Dillen and Fokkema 1991;Stoffa et al 2006;Zhao, Sen and Stoffa 2017a). Various migration methods utilizing DPW data have been introduced.…”

“…They utilize plane-wave vertical delay time (Akbar, Sen and Stoffa 1996) to project time domain DPW data to the subsurface. Zhao et al (2017a) employed the adjoint-state method to introduce an RTM strategy using time domain DPW data. Zhao, Sen and Stoffa (2016) proposed an efficient frequency-domain DPW RTM method where images can be produced by multiplying frequencydomain plane-wave Green's functions with the corresponding frequency-DPW data.…”