4D Permanent Reservoir Monitoring, based on permanent installation of seabed sensors to carry out frequent 4D seismic surveys of oil or gas reservoirs, is allowing collection of data that can be used by operators to monitor how oil, water and gas move in a complex reservoir over time. Once processed, the data helps produce detailed maps of underground geological structures and their evolution, allowing a better understanding of where new wells should be drilled to improve hydrocarbons recovery. ASN’s PRM solution is based on a very reliable purely passive optical subsea architecture and produces unsurpassed quality reservoir data.

Permanent Reservoir Monitoring with optical sensors which allows:

- Best in class 4-D seismic data recollection
- Increased oil recovery  (thank to optimized drilling and reservoir model tuning)
- Increased HSE performance thanks to possible real time monitoring of caprock integrity close to the injectors


In the North sea, ASN Norway installed its Optowave PRM system on the Ekofisk field operated by ConocoPhillips. It has been used regularly by the platform operator to get very accurate images of the distribution of the hydrocarbons in this complex reservoir, allowing a better prediction of its evolution in time. ASN was able to demonstrate on Ekofisk both the high quality of the seismic data gathered and the very low failure rate for the sensors due to the all optical passive design of the subsea network.

Recently, ASN has been awarded by Equinor a  fiber optics cable subsea deployment for a 4D Seismic deployment to be used to monitor the reservoir of the Johan Sverdrup development.