Early warning ultra-light marine seismic 4D time-lapse detection system
Paper presented at Paper presented at the EAGE Annual 2023, 5-8 June 2023, Vienna, Austria, presented by Per Eivind Dhelie
The Edvard Grieg field is located 180km offshore the west coast of Norway. The field was discovered back in 2007 and production came on stream in 2015. Oil production is around 90 to 100.000 bbl per day through 13 horizontal production wells. Reservoir pressure support is maintained from 4 active injection wells. Regular full-field 4D OBC seismic campaigns have been repeated four times to monitor fluid flow and production effects in the reservoir. The extensive amount of high-quality seismic data has provided a precise understanding of the dynamics of the reservoir and has so far supported two drilling infill campaigns on the field.
Edvard Grieg is now a mature field and supporting frequent full field 4D seismic campaigns could become less economically viable. An innovative light and focused 4D seismic monitoring approach was thus introduced and tested. It consists of detecting changes in a specific area of the subsurface using a few optimally placed source and receiver pairs. 4D seismic changes in the reservoir can be tracked in the non-migrated domain by comparing the resulting processed traces acquired at different times.
This method has already been developed and demonstrated onshore for SAGD & CCS, and the main objective of this study was to adapt it to offshore challenges and show its robustness by detecting the water-front sweep in the reservoir. The end goal is to offer an affordable solution to complement and help trigger or space out larger 4D campaigns over a dynamically changing reservoir.