Ronan Sablon

Multiple attenuation for variable-depth streamer data: from deep to shallow water

Summary Variable-depth streamer acquisition is becoming a key technique for providing wide bandwidth seismic data. Varying the receiver depth creates wide receiver ghost diversity and produces a spectacular increase in the frequency bandwidth. However, compared to conventional data, this variable-depth streamer data implies a major challenge in processing: how to deal with various receiver ghosts. The ghosts have to be preserved up to the deghosting step. Here we present the implication for the following de-multiple methods: Shallow-Water Demultiple, Tau-P deconvolution and Surface-related multiples elimination in deep and shallow water environments.

Challenges in Processing Variable-depth Streamer Data

Summary Variable-depth streamer acquisition is emerging as a key technique for providing wide bandwidth seismic data. With several data sets acquired across the world, it has consistently produced high quality images in terms of seismic resolution, layer stratigraphy and low-frequency penetration. By varying receiver depth, variable-depth streamer acquisition introduces receiver ghost diversity over different offsets. Such diversity enables a joint deconvolution method to fully remove the receiver ghost. Variable-depth streamer data also tends to be less noisy due to the deep tow of cables. These two factors allow variabledepth streamer data to have a spectrum from 2.5 Hz up to the source notch. Challenges in processing include: how to maintain the full bandwidth in the data, how to effectively remove multiples, and how to robustly build a velocity model. This paper will discuss each of these challenges and their solutions.

Variable Depth Streamer – Benefits for Rock Property Inversion

The quality of an inversion depends on the seismic frequency content, the signal-to-noise ratio, the wavelet, and the low frequency model used to incorporate information outside the seismic bandwidth. In order to quantify the benefits of broadband seismic data for inversion, we compare pre-stack inversion results from conventional streamer and variable depth streamer data from NW Australia. The inversion results are combined with a Bayesian fluid classification scheme to map three rock facies and quantify associated uncertainty.

What to Expect from Variable-Depth Streamer Data

Variable-depth streamer acquisition is emerging as a key technique for providing wide-bandwidth seismic data. This technique allows us to obtain a usable bandwidth from 2.5 Hz up to the source notch. It has consistently produced high-quality images in terms of seismic resolution, layer stratigraphy and low-frequency penetration. Seismic interpretation and inversion becomes easier and more robust.