Imaging the total wavefields by reflectivity inversion using amplitude-normalized wavefield decomposition: field data example

Based on an example acquired with dual-sensor towed-streamers and time and depth distributed sources, we image the total up and down going wavefields using primaries and multiples. The imaging framework is based on computing the subsurface impulse response (i.e., reflectivity). At every depth level, the latter can be obtained by inverting the matrix form of an integral equation defined in terms of the amplitude-normalized upgoing pressure and downgoing vertical velocity wavefields. This procedure gives the reflectivity matrix. The total upgoing wavefield used in the imaging scheme is composed of the scattered energy from primaries and multiples. The primary reflected wavefield is generated by a direct downgoing source wavefield, which is mostly passing the acquisition surface at offsets smaller than the nearest data channel. Hence, the most relevant part of the direct wavefield is not measured in the studied example. From the near-field pressure measurements, we predict the missing direct arrivals needed to image the primary reflected wavefield; and we then synthesize the total downgoing wavefield by adding the downgoing scattered energy. By downward extrapolating the total up- and downgoing wavefields, the information of the subsurface is extracted from the reflectivity matrix in the spatial and angular domains.