Expertise
Project Case Study: World-Class Offshore Pipeline Crossing Completed with Advanced Horizontal Directional Drilling Technology in China
2026-07-10
By the end of June 2026, the pilot hole for the subsea pipeline—a key control project within the Shenzhen-bound offshore natural gas pipeline initiative developed by CNOOC Hainan—was successfully completed along its entire length. This achievement marks the passing of the most technically challenging milestone for what is set to become the world's longest directional drilling crossing project, laying a solid foundation for its scheduled commissioning.
With a total HDD crossing length of approximately 7,000 meters, this project represents an extreme challenge for the global trenchless industry and demonstrates the capability of modern HDD technology in large-scale offshore pipeline installation.
- Ⅰ. Project Highlights
- *Project Type: Offshore Natural Gas Pipeline Crossing
- *Construction Method: Horizontal Directional Drilling (HDD)
- *Crossing Length: Approx. 7,000 meters
- *Pipe Diameter: φ508mm
- *Equipment Models: Goodeng Machine custom-designed 600-ton and electric-drive 1050-ton horizontal directional drilling rigs.
- *Application：Subsea Pipeline Installation
- *Main Challenges: Long-distance drilling, complex geology, high accuracy requirements
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*Major Benefits: Environmental protection; reduced construction impact; reliable pipeline installation
Ⅱ. Project Challenges: Extreme Distance, Complex Geology and High Accuracy Requirements
Long-distance offshore HDD projects require precise engineering control, advanced equipment capabilities, and extensive field experience. This project faced several major technical challenges.
1. Ultra-Long Distance Drilling with High Precision Requirements
During a conventional HDD operation, drill string control becomes increasingly difficult as the drilling distance increases. Over several kilometers, even small deviations can significantly affect the final pipeline installation accuracy.
To ensure the pilot hole was completed within strict alignment requirements, advanced guidance technologies, including high-precision navigation systems and gyroscopic measurement equipment, were applied throughout the drilling process.
The project team successfully achieved accurate trajectory control, ensuring that the offshore and onshore drilling sections connected precisely beneath the seabed.
2. Complex and Unpredictable Geological Conditions
The drilling path passed through highly variable underground formations, including hard rock layers, loose formations, and fractured zones.
Different geological conditions created significant challenges for drilling performance, including:
Increased drilling resistance in hard rock sections;
Potential instability in softer formations;
Risk of drilling fluid loss in fractured areas.
To overcome these challenges, the engineering team continuously optimized drilling parameters, including:
Drill bit selection;
Drilling pressure control;
Rotation speed adjustment;
Mud circulation management.
The ability to adapt quickly to changing geological conditions was essential for maintaining drilling efficiency and project safety.
3. Limited Geological Information During Offshore Construction
Due to the presence of an active navigation channel, traditional geological investigation methods such as vertical exploration shafts were not feasible in the construction area.
As a result, the project team had to rely heavily on:
Advanced geological prediction technology;
Real-time drilling data analysis;
Operator experience;
Accurate equipment control.
This required close cooperation between the drilling team, engineering specialists, and equipment operators throughout the entire construction process.
Ⅲ. HDD Construction Process: From Pilot Hole to Pipeline Installation
The HDD installation process was completed through several key stages:
Step 1: Pilot Hole Drilling
The drilling operation was carried out from both land and offshore sides. The drill heads advanced underground beneath the seabed and successfully intersected, creating a continuous pilot hole.
Step 2: Hole Enlargement
After completion of the pilot hole, multiple reaming operations were performed to enlarge the borehole diameter to meet pipeline installation requirements.
Step 3: Pipeline Pullback
The completed pipeline was then pulled through the underground bore path, achieving a safe and environmentally friendly installation without disturbing the seabed or marine traffic.
The completed pipeline was then pulled through the underground bore path, achieving a safe and environmentally friendly installation without disturbing the seabed or marine traffic.
Ⅳ. Why HDD Technology Was Selected
1. Minimal Environmental Impact
HDD allows pipelines to be installed underground without large-scale excavation, reducing disturbance to:
Marine ecosystems;
Coastal environments;
Existing infrastructure;
Transportation routes.
2. Improved Construction Efficiency
For long-distance crossings, HDD eliminates the need for extensive excavation, temporary structures, and major surface disruption, making it an ideal solution for complex infrastructure projects.
3、Suitable for Critical Infrastructure Applications
HDD technology is widely used for:
Offshore pipeline installation;
River crossings;
Highway and railway crossings;
Urban utility projects;
Long-distance energy transmission systems.
Ⅴ. Project Value: Supporting Cleaner Energy DevelopmentThis is a paragraph
The project is part of an offshore natural gas landing pipeline system developed to improve energy supply reliability in the Greater Bay Area. Once completed, the pipeline will provide a reliable natural gas supply channel for the Shenzhen region. The project will strengthen the local energy supply network, improve the flexibility of natural gas distribution, and support the transition toward cleaner energy solutions.
This successful offshore HDD crossing demonstrates the potential of trenchless technology in solving some of the world's most challenging underground construction problems. Through advanced equipment, professional engineering support, and continuous innovation, HDD technology continues to provide safer, more efficient, and more sustainable solutions for global infrastructure development.
This project represents a new benchmark for long-distance HDD applications and highlights the capability of modern trenchless technology in global energy infrastructure construction.
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Contact Information:
Contact: Ms. Bonnie
WhatsApp/Wechat: +86 18352020820
Email: luyurong@goodeng.com.cn