Huayuan News
On January 24, 2018, our company received a notification of award from Offshore Oil Engineering Co., Ltd., officially confirming our successful bid for the horizontal directional drilling (HDD) project for the Yacheng 13-1 pipeline landfall.
The scope of the Yacheng 13-1 project mainly includes:
* Installation of a new 24-inch (610 mm) dry gas submarine branch pipeline with a total length of approximately 25 km, running from YC13-1 AWA to the KP694 point of the gas export pipeline at the Hong Kong terminal, connecting via a subsea tee to the Zhuhai Gaolan terminal.
* Prefabrication, installation, and expansion bend connection of the subsea tee skid.
* Construction of the HDD segment for the pipeline’s landfall and terminal shore approach.
The designed wall thickness for the landfall segment is 22.2 mm. The pipe material is API 5L X65, and the anti-corrosion coating is 3LPP.
This HDD project is a full-package scope including geological survey, construction drawing design, and directional drilling construction. The total crossing length is approximately 900 meters, with a vertical depth of 98 meters from the entry point.
The entry point is located on the north side of the 50-meter platform at the Liwan 31 landing site, while the exit point is located underwater, where the water depth is around 10 meters.
The planned entry angle is 17 degrees, and the exit angle is 6 degrees. After completion, the pipeline will be pulled back in coordination with the offshore pipeline. The exit end will be connected to the marine pipeline using a flexible laying method.
Key difficulties and technical challenges of the HDD crossing include:
1. High rock hardness–According to preliminary geological investigations, the uniaxial compressive strength of the rock exceeds 100 MPa.
2. Large contrast between soft and hard layers– The difference between hard rock and soft seabed silt may lead to “stepped boreholes.”
3. Offshore exit operations– The offshore portion of the project involves critical operations such as sub-sea recovery of the drill bit, offshore hole reaming, offshore welding, and coordinated pullback with a pipe lay vessel.
Following receipt of the award notification, our company promptly established a technical steering group and a dedicated project team. In accordance with the contract requirements, the team mobilized to the site, and the project officially commenced on March 3, 2018. The HDD works are currently in the reaming stage.
