LoDRAG Mechanical Friction-and Wear-Reduction System
Weatherford developed the LoDRAG™ system as a centralizer and an axial drag-friction-reduction system to perform independently of drilling or completion mud-film strength or lubricity.
The small contact area of the rollers with the casing or borehole wall functions exceptionally well in under-pressured conditions, where risk of differential sticking is high.
LoDRAG tools have been used extensively to run sand-control screens into unconsolidated sandstone reservoirs, where the use of clean, non-damaging drilling and completion fluids give preference to mechanical friction reduction. Using LoDRAG tools in these reservoirs can reduce axial drag by up to 60 percent. The LoDRAG tools can reduce axial friction in cased holes by greater percentages, and are routinely used on ultra-long casing and liner strings. Use of the LoDRAG system has contributed to many record-length wells.
The LoDRAG tools provide optimal performance when:
- Casing, liner, and screens are being run into horizontal and extended-reach wells
- Centralizer wear may compromise the cement job
- Health, safety, and environmental (HSE) requirements ban the use of oil-based and pseudo-oil-based mud
- Under-pressured formations may cause differential sticking
- Run in conjunction with high-strength stop collars
Features, Advantages and Benefits
- The LoDRAG’s steel rollers help to avoid plowing through wellbore material that has settled on the low side of the hole, alleviating major drag problems in deviated and horizontal wells.
- Precision-machined inside diameter fits over the casing through the complete API tolerance range, providing excellent rotational performance in mud.
- When running casing through an open hole, the system’s smaller roller-contact area reduces the risk of differential sticking and maintains standoff.
- Rollers provide superior wear resistance and remain functional throughout the life of the well and can aid in casing or tubing retrieval, reducing replacement costs.
- Unique engineering and material selection ensures that axle shear stress remains within elastic limits, preventing roller failure and the additional cost
- of remediation.
- The system’s high-quality construction materials improve high-pressure/high-temperature capabilities, extending the life of the system.
Weatherford has developed an optional corrosion-resistant alloy (CRA) system for tubular applications to prevent direct, contaminating contact between the LoDRAG tool and CRA pipe. This optional corrosion-resistant compatibility system ensures that:
- Each centralizer and stop collar is completely coated with an isolating polyamid material or manufactured from a CRA-compatible material.
- Rollers and stop-collar set screws are made of corrosion-resistant material that is compatible with the pipe alloy. Contact your Weatherford representative for details.