Erik A. Eriksen

Considerations for high‐resolution VSP imaging

Vertical seismic profiling (VSP) data can complement surface seismic data where higher resolution is desired or necessary to fully understand a reservoir. VSP data typically provide greater resolution because of the inherently smaller Fresnel zone and because the bandwidth is usually wider than comparable surface seismic data. High fidelity images are required for effective reservoir monitoring. Also, special situations exist, such as attempting to image beneath salt or volcanics, where VSP data can potentially yield superior results because the seismic energy travels through the distorting overburden only once.

Removal of water‐bottom multiples and peg‐leg multiples via wavefield reconstruction

Wavefield reconstruction is a technique that reconstructs the primary and multiple wavefields from undersampled data. It has been found to be particularly effective for attenuation of high amplitude water-bottom or peg-leg multiples which obscure primary reflections of interest. Wavefield reconstruction is deterministic and robust in the presence of high amplitude coherent noise. In practice, the multiple wavefield is reconstructed (using the recorded data) and subtracted from the recorded data. Next the primary wavefield is reconstructed from these almost multiple-free input data. This primary reconstruction further attenuates the contribution of multiples and other unwanted wavefields. In addition, wavefield reconstruction properly handles dipping reflectors, curved reflectors, and diffractions.