Acoustic–Elastic Coupled Equations for Joint Elastic Imaging of TS and Sparse OBN/OBS Data

Elastic wave imaging with ocean-bottom four-component (4C) seismic data offers unique advantages in offshore oil and gas exploration, but for sparse ocean-bottom node/ocean-bottom seismometer (OBN/OBS) 4C seismic data, the problems of imaging acquisition footprints, poor phase continuity, and low signal-to-noise (S/N) persist. Pressure data acquired by towed streamer (TS) are dense and can be used in elastic imaging of sparse OBN/OBS data using acoustic–elastic coupled equations (AECEs). Based on the AECEs, we propose a novel method for elastic wave joint imaging of dense TS and sparse OBN/OBS seismic data, including joint elastic reverse-time migration (J-ERTM) and joint elastic least-squares reverse-time migration (J-ELSRTM), to solve the above problems in elastic imaging with sparse OBN/OBS data. J-ERTM of TS and OBN/OBS data can address the problem of imaging acquisition footprints, but with low S/N ratio. J-ELSRTM uses Hessian information and can theoretically suppress the negative influences caused by sparse acquisition, thereby obtaining better images than J-ERTM with higher S/N ratio. The results of synthetic and field data experiments show that our method is of prime importance for addressing the elastic wave imaging problems of sparse OBN/OBS data in deep-water oil and gas seismic exploration.