Application of optical cables for well logging in North Africa

Fiber-optic cables are increasingly used in North African wells for real-time seismic acquisition, well monitoring, and reservoir surveillance, offering higher efficiency, continuous data, and reduced environmental impact.

Seismic Acquisition and Well Logging

In North Africa, operators have successfully deployed fiber-optic borehole seismic solutions such as SLB's Optiq Seismic system to perform vertical seismic profiling (VSP) in onshore wells. Compared with conventional geophone acquisition, the fiber-optic solution recorded high-quality seismic data in just 7.5% of the acquisition time, reducing carbon emissions by over 92% . The system uses optical interrogator units at the surface connected to fiber-optic cables deployed via wireline, production tubing, or permanently cemented behind casing, enabling zero-offset, offset, walkaway, and walkaround VSPs efficiently .

Real-Time Well Monitoring

Fiber-optic well logging technologies, such as Silixa's Carina 100Xlog, provide continuous, real-time monitoring along the entire wellbore. This allows operators to detect complex flow regimes, leak paths, and well dynamics that conventional tools may miss. The system can reduce intervention time by up to 50%, saving several days of lost production while minimizing carbon footprint . Deployment is flexible, using wireline, slickline, or coiled tubing, and integrates with existing electromechanical tractors for extended-reach horizontal wells .

Permanent Fiber-Optic Installations

Permanent downhole fiber-optic cables are critical for long-term monitoring, supporting distributed temperature sensing (DTS), distributed acoustic sensing (DAS), and distributed strain sensing (DSS). These cables are designed to withstand harsh downhole conditions, including high pressure, temperature, and corrosive fluids, using a tube-in-tube design with hermetically sealed fibers . Such installations enable continuous surveillance of well integrity, production flow, and reservoir behavior over the life of the well.

Distributed Acoustic Sensing (DAS)

DAS technology transforms a single fiber-optic cable into thousands of acoustic sensors along the wellbore. This allows meter-scale seismic imaging, continuous production flow profiling, and real-time monitoring of hydraulic fractures without the need for individual downhole electronics . In practice, a single fiber installation can replace hundreds of conventional geophones, providing continuous data for VSP, production monitoring, and integrity evaluation, while detecting casing leaks and pressure anomalies weeks earlier than traditional methods .

Reservoir Surveillance and Environmental Monitoring

Solutions like FEBUS Optics' FOWell enable real-time monitoring of reservoir integrity, CO2 injection, and induced seismicity. These systems support carbon capture and storage (CCS) projects and optimize hydraulic fracturing in low-permeability reservoirs, minimizing production losses and environmental risks . Continuous fiber-optic monitoring ensures data-driven decision-making and reduces the need for frequent well interventions.

Benefits in North African Operations

• Efficiency: Faster data acquisition and reduced intervention times
• Environmental impact: Lower carbon emissions and minimized production downtime
• Data quality: High-resolution, continuous measurements along the entire wellbore
• Operational safety: Early detection of leaks, casing failures, and pressure anomalies In summary, the application of optical cables in North African wells enhances exploration, production, and reservoir management by providing continuous, high-quality data, reducing operational costs, and supporting environmentally responsible practices.