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Six Core Techniques for Efficient Horizontal Directional Drilling
2026-03-25
In trenchless construction, the skill of operating a horizontal directional drilling rig directly determines project efficiency, cost, and safety. We have summarized six practical techniques to help you maximize equipment performance and confidently handle complex working conditions.
Ⅰ. Precise Geological "Reconnaissance" and Drill String Selection
• Key Points: Not only should you understand the stratum type (clay, sand, gravel, or rock), but you should also pay attention to groundwater level, porosity, and obstacle distribution.
• Drill String Matching:
o Soft Soil Layers: Use a larger face drill bit to improve guiding efficiency.
o Gravel Layers: Use a wear-resistant tapered drill bit and pre-expand the hole using a reamer.
o Rock Layers: A rotary cutter or roller cone drill bit must be used, and the drill pressure should be adjusted according to the rock hardness.
• Goodeng Advantages: Goodeng GS series drilling rigs are compatible with various drill bit combinations, and their power head torque reserves are ample, easily handling sudden changes in formation.
Ⅱ. The "Three-Confirmation" Rule for Pilot Hole Construction
1. Launch Angle Confirmation: Accurately calculate the entry angle based on the pipeline burial depth and crossing distance, generally controlling it between 8° and 16°. Repeatedly calibrate the drilling rig angle using an inclinometer.
2. Trajectory Verification: After drilling each drill rod, verify the depth and azimuth angle using a handheld positioning device or a drilling measurement system to ensure the deviation is within the allowable range (usually no more than 1% of the drilling depth).
3. Exit Point Prediction: When approaching the exit point, reduce the advance speed and fine-tune the direction based on real-time data to ensure accurate drill bit exit, avoiding excessive adjustments that could cause an S-bend
Ⅲ. The "Step-by-Step Principle" for Hole Enlargement
• Staged Reaming: Reaming is generally performed in 2-5 stages, depending on the pipe diameter and formation conditions. For example, when laying a DN400 pipe, reamers of 300mm, 500mm, and 650mm diameters can be used sequentially.
• Reamer Selection:
o Clay Layers: Use barrel-type reamers with larger flow channels to prevent mud buildup.
o Sand Layers: Use reamers with wider cutting flanges, combined with high-pressure mud flushing.
o Rock Layers: Roller cutter combination reamers must be used, with more stages, and the diameter increment of each stage should be controlled within 100mm.
• Key Tips: During reaming, closely monitor torque and pull force changes. If the values suddenly increase, stop advancing, pull back for cleaning, remove rock cuttings, and then continue.
Ⅳ. Mud is the "blood," real-time adjustment is key.
Mud properties must be dynamically adjusted in real time according to the formation.
• Formula Adjustment:
Clay Layers: Prone to hydration and expansion, requiring the addition of anti-collapse agents to reduce mud filtrate loss.
Sand/Gravel Layers: Increase mud viscosity and shear force to enhance sand-carrying capacity. Appropriately increase the amount of bentonite and polymer.
Rock Layers: Focus on cooling the drill bit and lubrication. Increase the lubricant ratio and reduce torque.
• On-site Testing: Test the funnel viscosity, density, and pH of the mud at least twice per shift. When drilling through sand layers, the viscosity should be controlled at 45-55 seconds; for rock layers, it can be appropriately reduced to 35-45 seconds, but lubricity must be guaranteed.
• Circulation and Purification: Equip with a mud purification system to remove drill cuttings and recycle mud, which is both environmentally friendly and economical.
Ⅴ. Damage Prevention During Pipe Pullback
• Pipe Preparation: The welded pipe sections should undergo visual inspection and weld flaw detection. Install a rotary joint and reamer at the front end to prevent the pipe from twisting with the drill pipe.
• Pullback Speed Control: Maintain a uniform pullback speed, generally controlled at 0.5-1.5 meters per minute. Sudden acceleration and deceleration are strictly prohibited to avoid borehole collapse or pipeline damage.
• Drag Reduction Measures: Add sufficient lubricant to the drilling mud. For PE pipes, tie drag plates to the pipe ends to reduce friction area; for steel pipes, install roller supports to prevent wear on the anti-corrosion layer.
• Monitor Pullback Force: The Goodeng drilling rig's control panel displays the pullback force in real time. If an abnormal increase in pullback force is detected, stop immediately, analyze the cause (possibly borehole collapse or drill cuttings accumulation), flush and clean the borehole before continuing.
Ⅵ. The "Three-Inspection System" for Equipment Maintenance
1. Pre-shift Inspection: Check hydraulic oil level, engine oil, and coolant; check drill rod threads for damage and apply thread lubricant; check the mud pump piston and valve seat.
2. In-shift Inspection: Observe for leaks in the hydraulic system, ensure drill rod rotation is smooth, and check the track movement and outriggers for normal operation. Listen for any abnormal sounds from the engine and hydraulic pump.
3. Post-shift Maintenance:
o Clean mud and grime from the drill rig surface, especially the radiator fins, to prevent blockages and overheating.
o Lubricate moving parts (such as the chuck slide and power head guide rail).
o Check and tighten any loose bolts.
• Goodeng Support: Goodeng Machine providing original parts and professional training to ensure your equipment is always in optimal condition.
Common Problems and Emergency Handling
• What to do if the drill is stuck?
Immediately stop advancing, try reversing and pulling back a short distance, while increasing the mud flow rate to flush. If this is ineffective, use the drill rig's maximum torque for intermittent impacts; never pull forcefully.
• Severe mud loss?
This may be due to encountering fissures or sand layers. Immediately add a sealant (such as sawdust or a compound sealant) to the mud to reduce viscosity and increase its sealing capacity, sealing while drilling.
• Loss of guidance signal?
Check the probe battery, eliminate ground interference sources, or use a stronger transmission frequency. If necessary, use an artificial magnetic field method for repositioning.
Mastering these techniques will make your horizontal directional drilling operations much more efficient. Goodeng Machine not only provides you with high-performance GS series drilling rigs, but also hopes to share its technology with you to jointly promote the high-quality development of the trenchless industry. If you encounter any difficulties during construction, please feel free to contact us.
CONTACT:
Lynne
Email: liyi@goodeng.com.cn
Whatsapp: +86 18723398635
Tel: +86 18352020960