A Strategy for Optimal Marine 4D Acquisition

Abstract

Repeating source-receiver azimuths can be an important aspect of 4D acquisition. Seismic repeatability will decrease with an increase of source-receiver azimuth differences between base and monitor surveys. This paper discusses a marine acquisition strategy with respect to the optimal preservation of source-receiver azimuths in the presence of feathering. We show that repeating shot positions is favorable for azimuth preservation in 4D acquisition in combination with overlap configurations (additional outer streamers). With a dense streamer separation, source-receiver azimuths can be repeated very accurately by using this strategy. In a base survey, overlap configurations allow the vessel to follow the survey?s pre-plot sail lines with significantly reduced crossline deviations. A well-conditioned base survey simplifies and optimizes the repetition of vessel/source positions in a future monitor survey.