Learnings from 25 years of acquisition, processing, and interpretation of 4D seismic from the Ekofisk and Eldfisk fields

Ekofisk and Eldfisk are two giant chalk oilfields 10 kms apart in the southern Norwegian North Sea. Since the beginning of production in 1971/1978, both fields have experienced significant compaction and seafloor subsidence caused by pressure depletion and rock weakening from water injection. Reservoir compaction and resulting stress changes in the overlying formations impose challenges for exploitation, but also cause detectable seismic traveltime and amplitude changes making 4D seismic well suited for field monitoring.