Introduction

With the increasing development of offshore energy resources, submarine composite cables play a crucial role in power transmission, signal communication, and control systems for underwater production facilities. However, laying submarine cables in marginal oilfields presents unique challenges due to shallow water depths, irregular seabeds, and operational constraints.

This article explores:

• The challenges of submarine cable installation in marginal oilfields
• Full-scale laying analysis using OrcaFlex software
• Construction methods and new tail-pulling techniques for cable installation

Through simulation modeling and practical engineering applications, this study provides valuable insights into improving the efficiency, safety, and reliability of submarine cable laying operations.

Why Submarine Cable Laying is Critical for Marginal Oilfields?

1. Unique Challenges of Marginal Oilfields

Marginal oilfields are small, scattered reservoirs that require cost-effective and flexible infrastructure. Unlike large deepwater oilfields, marginal fields demand efficient cable-laying techniques due to:

• Shallow water depths (typically <50m) → Higher risk of external damage.
• Shorter distances between platforms → Requires precise routing.
• Limited economic feasibility → Must optimize installation costs.

2. Importance of Efficient Cable Laying

A well-planned cable-laying operation ensures:

• Stable power and communication between offshore platforms.
• Minimal mechanical stress on the cable to prevent long-term damage.
• Operational safety and cost reduction by optimizing installation techniques.

Simulation-Based Laying Analysis Using OrcaFlex

To ensure safe and reliable cable laying, a numerical simulation was conducted using OrcaFlex software, a powerful tool for analyzing dynamic cable behavior in marine environments.

1. Key Simulation Parameters

➡ Objective: To analyze tension distribution, bending radius, and stability during laying operations.

2. Simulation Results: Normal Laying Analysis

➡ Key Findings:

• The maximum tension occurs at the cable tensioner on the vessel.
• The minimum bending radius meets safety requirements, ensuring no excessive stress on the cable.

3. Sensitivity Analysis: Effect of Laying Tension and Water Depth

By adjusting laying tension and water depth, the sensitivity of cable performance was evaluated.

Effect of Laying Tension Variations

Effect of Water Depth Variations

➡ Conclusion:

• Tension changes affect cable departure angles but maintain safe bending radius.
• Cable-laying ships have a high tolerance for depth variations, ensuring flexibility in field operations.

Innovative Submarine Cable Laying Techniques

1. Pre-Installation Preparation

• Surveying seabed conditions for obstacles.
• Calibrating ship positioning to avoid deviations.
• Pre-testing cable integrity before deployment.

2. Overboarding and Laying Process

• "T-shaped" docking of cable-laying vessel for precise deployment.
• Using semi-circular overboarding equipment to reduce stress at the departure point.
• Controlling vessel speed (0.37–0.56 km/h) to maintain stable cable tension.

3. New Tail-Pulling Method for Final Cable Positioning

A new Ω-shaped tail-pulling method was introduced to improve final positioning.

➡ Benefit: Reduces energy loss, installation time, and cable stress.

Conclusion

The study of submarine composite cable laying in marginal oilfields has provided valuable insights into optimizing installation procedures.

Key Takeaways

✔ Simulation-based analysis using OrcaFlex enhances laying efficiency.
✔ Sensitivity analysis confirms operational flexibility under different water depths and tension conditions.
✔ New Ω-shaped tail-pulling method reduces cable stress and improves final placement accuracy.

These advancements contribute to safer, more efficient, and cost-effective cable installations for offshore energy projects.

Keywords

• Submarine Composite Cables
• Marginal Oilfield Development
• Cable Laying Analysis
• OrcaFlex Simulation
• Bending Radius Optimization
• Cable Tail-Pulling Method

References

1. Ma Y.P. (2025). Laying Analysis and Process Application of Submarine Composite Cables in Marginal Oilfields. Wire & Cable, 68(1), 32-37. DOI: 10.16105/j.dxdl.1672-6901.20240133
2. Huang Y., Wang E.J., Zhang C., et al. (2022). Sensitivity Analysis of Subsea Drilling Pipe Deployment Based on OrcaFlex. Petroleum Mining Machinery, 51(2), 22-31.
3. Shi Z.Y., Wu W.X., Zhang L., et al. (2022). Laying Technology of Offshore Wind Power Cables. China Offshore Wind Power Conference.
4. Xu H.B., Sha X.Y., Zhang Z.Y., et al. (2023). Numerical Simulation of Mechanical Characteristics of Submarine Cable During Laying Process. Southern Energy Construction, 10(1), 118-123.