Slovenia Well Logging Fiber Optic Cable Dimensions

Permanent downhole fiber-optic cables for well logging typically use a 1/4-inch (6.35 mm) control line with robust tube-in-tube construction for harsh environments.

Cable Design and Dimensions

Permanent fiber-optic cables used in well logging are designed to withstand high pressure, elevated temperatures, mechanical shock, and corrosive fluids. The standard configuration includes a fiber in metal tube (FIMT), where optical fibers are hermetically sealed in a stainless steel or INCONEL® tube. This FIMT is supported by an extruded polymer layer called the belt, and an outer tube provides the primary mechanical and pressure protection. The overall diameter of the control line is approximately 1/4 inch (6.35 mm), though the cable can be customized with additional armor, encapsulation, or filler depending on deployment requirements .

Fiber Types and Protection

The FIMT can contain a mix of single-mode and multimode fibers, allowing for distributed temperature, acoustic, and strain sensing (DTS, DAS, DSS). Filling gels inside the FIMT protect against microbending and chemical ingress. The outermost layer or encapsulation provides extra mechanical protection during deployment, ensuring long-term reliability in downhole conditions .

Retrievable Well Logging Cables

For retrievable well logging, such as the Carina 100Xlog system, the fiber optic cable is engineered for real-time data acquisition along the entire wellbore. These cables are compatible with wireline, slickline, or coiled tubing deployment and are designed to interface with electromechanical tractors for extended reach horizontal wells. While specific diameters are not always disclosed, these cables are precision-engineered to balance flexibility, strength, and minimal diameter for efficient deployment .

Summary

• Permanent downhole cable diameter: ~1/4 inch (6.35 mm)
• Construction: Tube-in-tube with FIMT, polymer belt, outer tube, optional armor
• Fiber types: Single-mode and multimode
• Protection: Filling gels, encapsulation, mechanical shielding
• Deployment: Permanent or retrievable, compatible with wireline, slickline, or coiled tubing These specifications ensure that fiber optic cables used in Slovenia for well logging are robust, reliable, and suitable for harsh downhole environments, while allowing customization for specific well conditions and sensing requirements .