HDD Stabilization in Saturated Fine Sand
France
“The difference was noticeable in the drill’s response and stability. The fluid went from being a problem to being part of the solution.”
A French civil engineering firm contacted QUIMACER during a horizontal directional drilling project to install a utility pipeline beneath a high-traffic urban area.
The borehole was approximately 180 m long, and it was necessary to maintain the trajectory and prevent surface subsidence.
The soil consisted of saturated fine sand, non-cohesive silt, and layers with low self-supporting capacity.
The customer was using a fluid that was too simple, designed to reduce initial costs, but with low suspension capacity and poor filtration control.
Problems arose during the pilot drilling and worsened during the enlargement phase, when the volume of debris generated increased.
Problems Identified
- Tunnel instability and partial collapses in the sandy section.
- Inadequate removal of debris during the widening project.
- Increased torque and greater pulling force.
- Risk of course deviation due to loss of ground support.
- Risk of delays in civil construction and penalties for occupying public roads.
Our Intervention
- QUIMACER reviewed the HDD method, drilling length, borehole diameter, and the type of soil encountered.
- A rheological deficiency was diagnosed: the fluid did not generate enough gel or bearing capacity to keep sand and silt in suspension.
- A polymeric fluid with improved suspension capacity, filtration control, and front stability was proposed.
- It was recommended to prepare the slurry by pre-hydrating the polymer before beginning the expansion phase.
- It was proposed to monitor viscosity, solids recovery, and pressure to prevent hydraulic fracturing or fluid loss to the surface.
Solution Implemented
- QUIMAGEL XG at 3 kg/m³ to provide high viscosity, structure, and suspension of detritus in fine sand.
- QUIMAGEL GNT at 1.5 kg/m³ to improve filtration control and cake formation on the walls.
- QUIMAPOL AL-60 at 2 kg/m³ as an anionic polymer that is easy to dose, with inhibitory and stabilizing effects.
- Adjust the flow rate to maintain sufficient annular velocity without overpressurizing the formation.
Target parameters: Marsh viscosity 60–75 s, continuous flow with suspended solids, and stable pumping pressure.
Results and Improvements
Elimination of recurrent collapses during the widening phase.
An improvement of more than 50% in detritus transport was observed due to return stability.
Reduction in torque and pulling force during final installation.
Less tool wear and less cleaning time between passes.
A reduction in the completion time of approximately 25% compared to the revised schedule following the incident.
| Parameter | Technical Details |
|---|---|
| Sector | HDD / Civil Engineering |
| Soil | Saturated fine sand and silt |
| Method | 180m |
| Critical Depth | Pilot and widening |
| QC Products |
QUIMAGEL XG, QUIMAGEL GNT, QUIMAPOL AL-60 |
| Recommended dosage |
3 kg/m³; 1.5 kg/m³; 2 kg/m³ |
| Key Improvement |
+50% debris removal; -25% completion time |
WHY QUIMACER?
- Fluid design tailored for HDD, not just vertical drilling.
- It improves ground stability and the cleanliness of the ring.
- Reduces the risk of collapse and deviation.
- Provides technical support for adjusting parameters during construction.
