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How to Make a Step Change in Seismic Image Quality: Experience From the Golden Eagle Field
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
The Golden Eagle Area Development (GEAD) lies 90 Km NE of Aberdeen in the Moray Firth and produces oil from turbidite sands of Lower Cretaceous and Upper Jurassic age at depths around 7,000 feet. These reservoirs have modest seismic contrasts and high seismic fidelity is needed to reveal subtle character and geometries.
Seismic imaging challenges in the Moray Firth include shallow velocity anomalies from Quaternary channels, overburden layers which create strong seismic multiples, and the high velocity Upper Cretaceous chalk. At GEAD the Top Chalk is unusually deeply eroded creating a rugose, high- contrast interface.
The combination of difficult overburden and subtle seismic character mean that seismic reservoir characterisation at GEAD requires an exceptionally high quality of seismic acquisition and processing. In 2015 an ocean-bottom-node (OBN) seismic survey was acquired over GEAD with unusually dense source and receiver sampling. This high-density OBN has delivered a step change improvement in seismic image quality compared with the best towed-streamer seismic.
Processing tests allow us to assess if an equally good image could have been obtained using less dense OBN sampling. These demonstrate that, when it comes to seismic imaging in the Moray Firth, more sampling is more.