*Blended Source Ocean Bottom Node Seismic Data Acquisition – A Case Study

Dr. Chris Walker and David Hays¹

Abstract

Blended or “simultaneous” sources have recently been introduced in land seismic operations with dramatic improvements in both crew productivity and data quality. The application offshore, however, has been relatively limited so far. For towed streamer surveys the firing of more than one source at a time increases the fold of coverage and hence data quality but for ocean bottom seismic (OBS) the use of two or more blended sources can have a dramatic impact on survey duration and hence cost. The challenge has been how to ensure not only no loss of data quality when multiple sources are fired at once but also that technical downtime of the equipment on the seafloor is minimized. Traditionally the performance of OBS systems has been hampered by the inherent technical downtime experienced by all the contractors operating ocean bottom systems – the terminations, connectors, power distribution and data telemetry components within a traditional ocean bottom cable (OBC) system are inherently prone to failure due to the intrinsic nature of the cable deployment /recovery cycle where the cables are stressed and de-stressed every time they are laid onto/recovered from the seabed. It is akin to recovering the full streamer spread every line change for towed streamer operations. The desire to improve operational performance was the driving force behind the development of autonomous nodal systems and its extreme reliability has allowed ever larger seafloor spreads to be operated.

AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain