Successful Completion of Shore Approach Pipeline Pulling for Niger to Benin Crude Oil Export Pipeline Project

Apr. 14th, 2022, two 28-inch shore approach pipelines of Niger to Benin Crude Oil Export Pipeline Project have been successfully pulled into place!

The project is located in about 30km east of Benin COTONOU Port in West Africa. Sea condition along the local coast are affected by landscape and climate factors, which resulting in perennial waves. It is learned that shore approach section is located in wave breaking area, and the wave impact force has a great influence on submarine pipeline pulling stability. Meanwhile, the wave flow direction makes offshore pipeline affected by lateral force during the pulling process, and ensuring submarine pipeline route does not produce deviation has become one of the difficulties in pipeline pulling operation.

In addition, pipelines are cement counterweight pipeline with a diameter of 711mm and a wall thickness of 19.05mm，besides the weight of a single pipe is close to 12t, and the pipeline surface roughness is really large, which has strict requirements on pulling pipeline traction force and pulling trolley bearing capacity. Moreover, large pipe diameter and cement counterweight also make pipeline really rigid, which requiring precise pipeline water inlet angle, bending, inflection point setting and guiding equipment strength.   

Ultimately, after in-depth analysis, calculation and verification conducted by  project team, bottom pulling method is adopted to pull offshore pipelines from pipeline prefabrication and launching site on land to the sea. Reasonable buoy bundling method and effective auxiliary materials are used to ensure pipeline remains a stable state in dragging process. Through accurate calculation, the proportion of pipeline buoyancy and bottom drag friction is determined to provide strong support for traction force. Simultaneously, high-power multifunctional tug with dynamic positioning function is used to ensure sufficient dragging force, effective speed control force and reliable ability to correct pipeline drag route deviation .

Successful completion of shore approach pipeline dragging is a major milestone in Offshore Terminal of Niger to Benin Crude Oil Export Pipeline Project, which has laid a solid foundation for submarine pipeline laying subsequently. Look forward to the good news that project team has successfully completed the next stage objectives!