SEISMIC & NATURAL HAZARDS

SEISMIC ACQUISITION

Imaging the underground is generally the purpose of seismic surveys.

By using distributed fiber optic sensing, the costs are optimized compared to conventional surveys (using geophones onshore or hydrophones offshore).

The FEBUS A1 (DAS - Distributed Acoustic Sensing) allows to analyze different seismic waves recorded by the optical fiber during 2D, 3D and 4D seismic survey.

This way, the interest in choosing a site is confirmed before starting drilling operations.

Furthermore, 4D seismic surveys provide a visualization of the evolution of the reservoirs throughout their years of operation.

The FEBUS A1 (DAS - Distributed Acoustic Sensing) also allows to achieve VSP (Vertical Seismic Profile) with a wireline or a slickline optical fiber cable or through a permanent deployment (either along the completion or more rarely behind casings).

VSP achieved by the FEBUS A1 (Vauvert, France) via wireline

Thanks to our distributed fiber optic solutions, our customer obtains, at every point along the structure:

• reliable measurements,
• very high spatial resolution data,
• contained costs of deployment and maintenance.

FEBUS devices quality and a good coupling of the optical fiber in the well enable to detect the arrival time of the P and S waves.

All FEBUS' fiber optic sensing technologies are non-intrusive and distributed. Moreover, the spatial resolution (gauge length) of the measurements performed with the FEBUS A1 can be adapted according to the geometry of the targeted geological formations.

Finally, the state-of-the-art sensitivity of the FEBUS A1 (DAS) allows to achieve a continuous monitoring of the local seismicity around the well.

To ease the data processing, FEBUS Optics provides preferred standard files format: HDF5 (native), SEGY, miniSEED...



NATURAL HAZARDS & SEISMOLOGY

FEBUS distributed fiber optic sensing devices cover many applications of Earth sciences: vulcanology, earthquake monitoring, observation of the Ocean-solid Earth interactions, monitoring of the evolution of glacier, of landslides...

Furthermore, our solution can work by plugging our interrogators to an already installed optical fiber cable, for example a telecom cable ("dark fiber") or a fiber optic cable deployed on purpose.

2.1 magnitude earthquake detected by the FEBUS A1 (Le Teil, France)
Publication:
Mw 4.9 earthquake of November 11.2019 in Le Teil, Lower Rhône Valley, France - C. Cornou, et al.; 2021; Comptes-Rendus. Géoscience, Online first

The state-of-the-art performances of the FEBUS A1 (DAS - Distributed Acoustic Sensing) meet the requirements of these applications:

• a noise floor of 3 pε/√Hz
• an adaptable gauge length before or after acquisition
• a very low frequency high sensitivity allowing to detect the farthest events (teleseisms)
• the ability to cover more than 200 km with only one device (long range version, while keeping a seismic quality)
• the possibility to increase the range by associating the FEBUS A1 (DAS) to the FEBUS REM (Range Extension Module).

Improvement of the data quality by adapting the gauge length after the acquisition
Publication:
On the impact of the gauge length value on Distributed Acoustic Sensing data quality - C. Jestin, et al.; 2020; Conference Proceedings, 82nd EAGE Conference and Exhibition

The FEBUS A1 (DAS) offers many opportunities:

• monitoring of the volcanoes activity
• creation of a map and the measurement of the seismic activity of a region
• observation of the low frequency activity of a region (microseismic pics, teleseisms, etc...)
• visualization of P waves and S waves
• production of a passive imaging of the subsurface thanks to a noise tomography
• detection of landslides and the control of the evolution of the glaciers

FEBUS A1 acquisition: 41 km, 6000 sensing channels (Toulon, France)
Publications:
Distributed sensing of earthquakes and ocean-solid Earth interactions on seafloor telecom cables - A. Sladen, et al.; 2019; Nature Communication
Preliminary assessment of ship detection and trajectory evaluation using Distributed Acoustic Sensing on an optical fiber telecom cable - D. Rivet, et al.; 2021; The Journal of the Acoustical Society of America

Seismic acquisition in deep water achieved by the FEBUS A1 (non-stacked, non-filtered data: a unique shot)

Real-time and continuous high-resolution data are obtained. They are accurate, reliable and precisely localized.



MINING

Mining can cause induced seismicity in the surroundings. Mine-tailing dams are particularly sensitive infrastructures. Thus, ensuring a real-time and continuous monitoring of the entire site is essential to informe as quickly as possible the operators when a defined alert threshold is reached.

The FEBUS A1 (DAS - Distributed Acoustic Sensing) allows to:

• optimize production,
• decrease operating costs,
• prevent any potential negative environmental impact.

Continuous monitoring	Reliable and accurate measurements	Very high resolution data	Real-time alerting