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Joint Reverse-Time Imaging Condition of Seismic Towed-Streamer and OBN Data

Reverse-time migration (RTM) of the towed-streamer seismic data is widely used for imaging subseabed layers. In the areas with high-velocity shielding layers, the RTM images of the deep layers may be severely damaged by the coherent noises. The pressure component of ocean bottom nodes (OBNs) data contains abundant reflection waves from deep layers and can be used as supplementary to the towed-streamer data. Joint RTM of these two kinds of data has the potential to acquire better migration images. However, using the traditional cross-correlation imaging condition, the joint RTM images of low signal-to-noise ratio (SNR) seismic data are disappointing due to the imaging noises. In this letter, we propose a new imaging condition to improve the joint migration images. The proposed imaging condition decreases or enhances the imaging values according to the similarity between the backward-propagating receiver wavefields of the towed-streamer and OBN pressure data. In this way, the SNR of the joint migration images is increased. The proposed imaging condition is applied to the synthetic datasets of a complex velocity model containing a high-velocity salt body. The tests demonstrate that joint RTM images obtained using the proposed imaging condition are much better than ones obtained using only the towed-streamer data.